Mme Maria

Teresa Da

Cruz Carvalho

M Didier Perrin

M Xiao-Lu

M Philippe Gong

M Wavrer

Bardia

Keywords:

I wish to express my gratitude to China Scholarship Council (CSC) for the financial support during the last five years in France and to my supervisors for the financial support for seven months.

Thanks to the secretaries of the pôle HETIC Mme Sophie LEVEQUE and Mme Christine HENRY, and the secretaries of the doctoral school: Mme Isabelle LECLERCQ, Mme Pascale DENIS and Mme Therese KAZARIAN, for their help throughout my PhD study. I want to thank my friends in UTT for their valuable aids and supports, and all my other friends other contries. Thanks to Yi HUANG, Shijie ZHU, Xue QIAO, Feifei ZHANG, and Fang DAI, who always help me and give me their best suggestions. Special thanks to Nan JIANG, Xin WEN and Fangzhou DENG for their support and encouragement on everything for me during all these years.

Last but not the least, I would like to thank my parents, for giving birth to me at the first place and supporting me spiritually throughout my life.

List of Figures

Figure 1-1 European plastic converter demande by polymers types in 2016 [START_REF] Plasticseurope | Annual Review 2017-2018[END_REF] .......................... Figure 1-2 European plastics converter demand by segments and polymer types in 2016 [START_REF]PEMRG) / Consultic Marketing & Industrieberatung GmbH[END_REF] ..... Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France .......... Figure 1234The objectives of recycling, reuse and valorization of each WEEE category [START_REF] Deprouw | Rapport Annuel du Registre des Déchets d'Équipements Électriques et Électroniques -Données 2015[END_REF] ....... Table 1-

List of Tables

General Introduction

The amount of WEEE (Waste Electrical and Electronic Equipment) has significantly increased in recent years. The production of electrical & electronic equipment leads to the growth of WEEE, the e-waste includes computers, consumer electronics, fridges, etc. which have been disposed by their original users. It contains materials such as ferrous/ non-ferrous metals, glass, plastics, etc. and these materials reappear as recycled products or in the form of energy after recycling and valorization. Since different families of plastics cannot be treated together, the sorting of plastics into their family species is an essential process for plastic recycling. Among different plastic sorting technologies, the most widely used methods are density sorting and optical sorting. However, both of them have their disadvantages, for example, dark colors or/and similar densities of plastics present difficulties for the separation process. Other limitations of plastic recycling also exist, since many plastics contain added bromine flame retardants, which is also a difficulty in the recycling process. Plastic materials made up 16.6% of the materials of WEEE in 2016 in France [START_REF] Deprouw | Rapport Annuel du registre des déchets d'équipements électriques et électroniques -Données 2016[END_REF]. Among these plastics, ABS (acrylonitrile-butadiene-styrene), PS (polystyrene) and PP (polypropylene) are the highest percentages. In a case study of the small WEEE, these three, ABS, PP and PS, account for 65% of all plastic materials [START_REF] Maris | Characterizing plastics originating from WEEE: A case study in France[END_REF]. Recycling of waste plastics can reduce the pollution caused by plastic incineration and landfill, which is of great significance to environmental protection, energy saving and emission reduction. Efficient recycling requires individual polymer types and grades before the regeneration process to obtain high purity recycled materials. In particular, WEEE consists of about 30% plastics that contain toxic flame retardants such as tetrabromobisphenol-A (TBBPA) [START_REF]Observatoire Ré gional de la Santé de Rhône-Alpes[END_REF]. These flame retardants can form toxic halogen dioxin or furan through incineration and landfill activities. Thus, the plastics containing these toxic substances need to be separated before other specific recycling processes are undertaken. Nowadays, the two most representative industrial sorting technologies are sink-float separation and optical separation, these methods have limits when the difference in densities is less than 0.1kg/m 3 or when the plastics are in dark colors [START_REF]Eco3e[END_REF]. ABS and HIPS are thermoplastics having styrene structure, which can provide impact strength and rigidity, and easy processing. They have similar densities of 1.05-1.07 and 1.02-1.04 kg/m 3 , respectively. The density of 20% talc filled PP is also around 1.05kg/m 3 . This is an obstacle to their effective separation, especially when these polymers have dark colors. The thesis project involves applying a mining technology, froth flotation, to the plastic sorting problem. This is widely used in the concentration of ores after grinding. Preliminary studies have shown its high potential for sorting plastics. The process implementation criteria are significantly different for plastics and have critical effect on the quality of the separation. One of the main points of our investigation concerns the modified wettability of polymer surfaces with selective surfactant agents. This depends on the types of material and its degradation on surface. The degradation is relative to the aging (End of life product) and the contamination received during utilization. Froth flotation is investigated as a new method for separating specific plastics from the mixture. The separation is based on the modification of plastic surfaces in order to differentiate the wettability on their surfaces. With the help of surfactant agents, the more hydrophobic plastic surfaces have a higher attachment to air bubbles than the hydrophilic plastic surfaces. Therefore, the more hydrophobic plastics float more easily over the floating medium whereas the more hydrophilic plastics sink down to the bottom of the flotation cell. Prototypes have showed the potential of this technology. With the exception of PET / PVC sorting (packaging), little work has been done on plastics in France. Therefore, more in-depth work is needed, in addition of this thesis. Chapter 1 deals with the state of art of plastics in WEEE and a literature review of flotation separation. An MFA (Material Flow Analysis) case study is conducted (work presented in Chapter 2) to evaluate the improvement of plastic sorting by the flotation technique. The choice of plastic and selection of surfactants with the experimental design are explained in chapter 3. The two main experimental aspects are physical phenomena of wetting on plastic specimens by surface determination (work presented in Chapter 4) and wetting on plastics in flotation (work presented in Chapter 5). The main criteria to be studied are the aging effect, additive effects on plastics and the optimum conditions for flotation separation. Then the correlation between two experiments will be studied (work presented in Chapter 6).

List of abbreviations

Background of plastic industry

Plastic is a material consisting of a wide range of synthetic or semi-synthetic organics that can be molded into solid objects of diverse shapes. Plastics are typically organic polymers of high molecular mass, but they often contain other substances, such as additives and plasticizers. Additives improve performance and reduce production costs, for example: fire retardants lower the flammability of the material as they are relatively inert. Fire retardants are also inexpensive materials reducing the product's price. In order to avoid organic polymers which are too wooden for particular applications, they are commonly blended with plasticizers that help improve rheology.

Plastics are most commonly derived from petrochemicals. Due to their relatively low cost, ease of manufacture, versatility, and imperviousness to water, plastics are used in a wide and expanding range of products, closely connected with our daily lives, as shown in figure 1-1. They are used in packaging and in buildings, such as piping and window frames, and have many other uses including automobiles, furniture, toys, etc. [START_REF] Plasticseurope | Annual Review 2017-2018[END_REF] Plastics are usually classified by their chemical structure, such as carbon chains. In general, they are divided into two families: thermoplastics and thermosets. Thermoplastics are the plastics that do not undergo chemical change in their composition when heated and can be molded again and again, due to their liner structures. Examples include polypropylene, polyethylene, polycarbonate, and so on. While thermosets, such as polyurethane, melamine resin, can melt, they can only be shaped once. After they have solidified, they stay solid. In the thermosetting process, an irreversible chemical reaction occurs. For this reason, in plastics recovery, thermosets are more difficult to deal with, the recycling rate is much lower than thermoplastics. There are other classifications, based on physical properties, or qualities that are relevant for manufacturing or product design.

Plastics are valuable materials that should be recycled. In the United States, the world's largest consumer of petroleum, roughly 5% of total petroleum used goes to the production of plastics. That works out at approximately 330 million barrels of oil per year. Estimates are difficult to come by, and fluctuate a great deal based on the source, but the basic message is that most plastic is made from petroleum. By doing more with less, plastic products help promote energy efficiency, reduce greenhouse gas emissions and conserve resources. And in many cases, we can enhance plastics' environmental benefits by recycling after use.

The Plastics industry in Europe

The Plastic industry plays an important role in modern society. In Europe, the growth of the plastics industry has a multiplier effect on numerous important sectors of the economy. The plastics industry is a key enabler of innovation for many products and technologies in other sectors of the economy like healthcare, energy generation, aerospace, automotive, maritime, construction, electronics, packaging or textile, as shown in figure 12. According to a report by PlasticsEurope in 2018 [START_REF]PEMRG) / Consultic Marketing & Industrieberatung GmbH[END_REF] , the plastics industry gives direct employment to over 1.5 million people in Europe, at the same time the European plastics' industry had a turnover of 350 billion euro in 2016. In the same year, 27.1 million tons of plastic waste were collected through official schemes in the EU28+NO/CH in order to be treated. 72.7% was recovered through recycling and energy recovery processes, 31.1% recycled and 41.6% recovered, while 27.3% still went to landfill. In 2016, for the first time, more plastic was recycled than landfilled. From 2006 to 2016 the volumes of plastic waste collected for recycling increased by 79%, energy recovery increased by 61% and landfill decreased by 43%, but the aim of the EU is a zero plastics to landfill by 2025 scenario [START_REF] Engelmann | Zero Plastics to Landfill by 2020[END_REF]. In response to the decrease of landfill, materials and energy recovery is increasing, which sets a challenge for recycling processes.

So far, plastic packaging recycling ranks first in all applications of plastics recycling, the rate was 40.9% in 2016 [START_REF]PEMRG) / Consultic Marketing & Industrieberatung GmbH[END_REF]. The rise of the collection and recovery of plastics from waste electrical and electronic equipment, end-of-life vehicles and construction waste will also help to increase the quantities of available material for reuse in new products.

Context of WEEE

General features

The production of electrical & electronic equipment leads to the growth of waste electric & electronical equipment (WEEE), a category of waste, the term used to describe old, end-of-life or discarded appliances using electricity. It includes computers, consumer electronics, fridges, etc. which have been disposed by their original users. It contains materials as ferrous/ non-ferrous metals, glass, plastics, etc. After recycling and valorization, these materials reappear as recycled products or in a form of energy. As shown in figure 123, the input flows, indicating the put-on-market residential EEE have been rising steadily since 2013. And the year of 2015 shows a big increase of EEE input due to solar panels [START_REF] Deprouw | Rapport Annuel du registre des déchets d'équipements électriques et électroniques -Données 2016[END_REF].

Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France

In the year of 2016, 667,261 tons of WEEE were collected in France (equivalent to about 12 million fridges). This number is 15.5% higher than collected WEEE in 2015 [START_REF] Deprouw | Rapport Annuel du Registre des Déchets d'Équipements Électriques et Électroniques -Données 2015[END_REF]. The efficiency of this process was improved by facilitating mechanisms that offer eco-friendly waste management institutions [START_REF] Ecomobilier | Ecomobilier. Eco-friendly waste management institutions[END_REF] and the new European directive. According to the 2002/96/CE, the collection objective target is set at 45% for 2016, the target was therefore satisfied for French WEEE (45.2%). In the same year, 80% of treated WEEE was recycled, which is 16.9% more than 2015. The non-recycled wastes were either eliminated (10%), used for energy purposes (8%) or reused completely or for spare parts (1% each, respectively). In future plans, where new WEEE treatment processes will be included to improve the treatment rates, the collection objective target is expected to be raised as well.

Legislative aspects of WEEE

The WEEE directive has two main priorities, firstly to prevent the generation of WEEE, secondly to encourage environmental ways of reusing, recycling and recovering WEEE in order to reduce landfill, thus reducing pollution.

In order to increase the collection quantity, the European Directive 2002/96/ EC related to WEEE, concerned with the collection and treatment of end-of-life products and the production of waste, set the target of WEEE collection [START_REF]Directive 2012/19/EU of the European Parliament and of the Council on waste electrical and electronic equipment (WEEE)[END_REF] [START_REF] State | Waste Electrical & Electronic Equipment (WEEE)[END_REF].

WEEE regulations include:

• the eco-design of WEEE, to promote the re-use and treatment of WEEE

• the selective collection of WEEE, with progressive collection targets and an obligation to take back the old device free of charge when selling a new similar device • the systematic processing of certain components (printed circuit boards, discharge lamps, etc.) and hazardous substances to prevent pollution • the reuse, recycling, recovery of collected WEEE, with high recycling and recovery targets, the priority to be given to the reuse of whole appliances.

According to EU legislation, WEEE can be divided into 11 different categories as listed below [START_REF] Engelmann | Zero Plastics to Landfill by 2020[END_REF]:

1.

Large Household Appliances Washing machines, Dryers, Refrigerators, Air-conditioners, etc.

2.

Small Household Appliances (SHA) Vacuum cleaners, Coffee Machines, Irons, Toasters, etc 3.

Office, Information & Communication Equipment PCs, Laptops, Mobiles, Telephones, Fax Machines, Copiers, Printers etc.

4.

Entertainment & Consumer Electronics Televisions, VCR/DVD/CD players, Hi-Fi sets, Radios, etc 5.

Lighting Equipment Fluorescent tubes, sodium lamps etc. (Except: Bulbs, Halogen Bulbs) 6.

Electric and Electronic Tools Drills, Electric saws, Sewing Machines, Lawn Mowers etc. (Except: large stationary tools/machines) 7.

Toys, Leisure, Sports and Recreational Equipment Electric train sets, coin slot machines, treadmills etc. 8.

Medical Instruments and Equipment 9.

Surveillance and Control Equipment 10.

Automatic Issuing Machines 11.

Solar panels

From August 15 th 2018, the new categories are: 1. Temperature exchange equipment: fridges, freezers, air conditioning, etc. 2. Screens, monitors, and equipment containing screens having a surface greater than 100cm² : TVs, computer monitors, etc. 3. Lamps 4. Large equipment (any external dimension more than 50cm): washing machines, dish washers, cooking stoves and ovens, cookers, lamps, large printers, copying equipment, large equipment in general, etc. 5. Small equipment (no external dimension more than 50cm): vacuum cleaners, calculators, video cameras, cameras, hi-fi equipment, watches and clocks, smoke detectors, payment systems, etc.

6. Small IT and telecommunication equipment (no external dimension more than 50cm): mobile phones, tablets, routers, laptops, GPS, printers, etc.

Solar panels

The WEEE directive designates safe and responsible collection, recycling and recovery procedures for all types of electronic waste. It has set targets for WEEE recovery about 60% to 80% [START_REF] Engelmann | Zero Plastics to Landfill by 2020[END_REF]. However, the recovery of only metals and glass is far behind the requirement, as plastics account for a large proportion of the WEEE flux. Compared to other materials, plastic is more difficult to deal with by reason of the complexity of resin families and additives. Therefore, it is necessary to improve the recovery of plastic. Apart from that, the recovery and recycling of plastic also reduces energy consumption and saves raw materials.

Hazardous Substances

A large percentage of WEEE plastics have been found to contain hazardous substances, including brominated flame retardants (BFR), chlorine (Cl), cadmium (Cd) and antimony (Sb). In order to restrict their use, the EU directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, Restriction of Hazardous Substances (RoHS), has been enforced (Directive 2011/65/EU) [START_REF] Parliament | Directive 2011/65/EU of the European Parliament and of the Council on the restriction of the use of certain hazardous substances in electrical and electronic equipment(WEEE)[END_REF]. RoHS puts a limit on material recycling of WEEE containing more than 1000 ppm in lead, mercury, hexavalent chromium, polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE), 100 ppm in Cd. This will be illustrated in detail in chapter 1.4.

WEEE Treatment in France

General information on WEEE flow

WEEE is divided into two aspects according to their origins: household and professional. Professional WEEE means waste from business equipment, for example an electric or electronic dispenser such as a hot drink dispenser. Another example is a photocopier weighing more than 35kg, while a small photocopier used at home is in the household WEEE category. In 2016, 633 million pieces of equipment were put on the market in France, representing 1.73 million tons of EEE (1.47 million in the household category), basically the same as in 2015. Heading the list in terms of unit quantities are categories 5, 3 and 2, while category 1 heads the list in terms of weight. 527 thousand tons of WEEE were collected (495 thousand tons from household WEEE), 522 thousand tons were treated (492 thousand tons from household WEEE) [START_REF] Engelmann | Zero Plastics to Landfill by 2020[END_REF].

WEEE composition

After dismantling, WEEE provides a substantial volume of secondary raw materials: ferrous metals, non-ferrous metals, glass, plastics, etc. There are also some specific components present in WEEE: batteries and rechargeable batteries, cathode ray tubes (largely in TVs), printed circuit boards, LCD screens, relays or mercury switches, electric wires, cartridges and printer toners, etc. In addition, in the 2016 treated household WEEE stream, large household appliances (LHA) noncold and cold represented 40% and 18%, small household appliances (SHA) represented 27%. According to data from figure 1-5, with detailed information listed in the table, plastic materials comprise 16.6% of the materials of WEEE (2016). Among these plastics, ABS (Acrylonitrilebutadiene-styrene), PS (polystyrene) and PP (polypropylene) are the three highest percentages. In a case study of small WEEE category represented, for instance, by IT (computers, phones, printers, etc.), culinary equipment, audio/video, vacuum cleaners, hand electric tools, personal care products and toys, the three most represented are ABS, PP and PS, they account for 77% of all plastic species [START_REF] Maris | Characterizing plastics originating from WEEE : A case study in France[END_REF].

The Recycling process of WEEE

Upon its arrival in a treatment center, WEEE undergoes various operations concerning dismantling, cleaning, grinding and sorting. These steps vary depending on the stream to be treated and recycling processes implemented by operators. The treatment usually takes place in six major steps [START_REF] Deprouw | Rapport Annuel du registre des déchets d'équipements électriques et électroniques -Données 2016[END_REF]: 1. dismantling (manual separation of different components such as metals, plastics, wires, circuit boards, etc.) and remediation (removal of pollutants); 2.

grinding equipment into small pieces; 3.

electromagnetic separation of ferrous items; 4.

optical sorting for separating the electronic cards, which are subsequently recovered through another recycling process to recover precious metals contained in these fractions; 5.

separation of nonferrous metals (including copper); 6.

separation of plastic by density or optical sorting. Sometimes the first two steps are inversed or repeated for finer separation. Take SHA for example, the SHA stream consists of over 200 different types of products whose average weight is 2 to 3kg, including a wide range of products like vacuum cleaners, coffee makers, printers and mobile phones. The SHA stream consists of ferrous metal (40%), non-ferrous metal (9%), plastics (20%), etc. [START_REF]Flux DEEE_PAM[END_REF] The SHA will be collected to undergo a coarse grinding which helps extract the components, then will be manually depolluted. Staff remove and separate hazardous substances and other materials that could affect the quality of metals and plastics during the following steps.

Once the depollution is completed, the remaining elements will go through a finer crush and a series of processes to separate the ferrous and non-ferrous metals, plastics, and circuit boards.

No matter which step order is taken, the aim is to recycle the waste to achieve the goal of the objective set by the European directive: more environmentally friendly recycling. The consumption of electrical and electronic equipment is steadily rising and the materials of the electrical and electronic devices are quickly replaced with better performing ones. Therefore, the amount of plastics is increasing and represents a significant proportion of WEEE.

It is urgent and necessary to find new uses for the materials in the waste. The treatment of WEEE involves many materials (metals, glass, plastics, etc.), however, plastics are poorly valued because of their complexity. According to their principal, mechanical recycling seems the most suitable and probably the most environmentally friendly process compared to chemical recycling and incineration. Nowadays the product design stage takes into account more consideration regarding the end of life, including dismantling, recycling process and environmental effects (the use of hazardous substances). The benefit to the environment of recycling WEEE is also considered in the life cycle assessment of a new product.

Plastic materials in WEEE 1.4.1 Definitions

Polymers are formed of macro molecules, composed of many basic units. Polymers range from familiar synthetic plastics to natural biopolymers that is fundamental to biological structures and function. Both types are created via polymerization of molecules called "monomers". Polymerization combines many monomers into a covalently bonded chain or network, during the polymerization process, some chemical groups may be lost from monomer.

Plastic is made from synthetic or semi-synthetic organic polymers. These organic polymers are malleable and can be molded into solid objects of diverse shapes. They are typically organic polymers of high molecular mass, but they often contain other substances. They are usually synthetic, most commonly derived from petrochemicals [START_REF] Visakh | Recent Developments in Polymer Macro, Micro and Nano Blends: Preparation and Characterisation[END_REF].

The majority of polymers are based on carbon chains alone or with oxygen, sulfur, or nitrogen as well. The side chains of the different molecular groups, hang from the backbone, they influence the polymer properties, and even a slight turning of the repeating unit's molecular structure has the effect on polymer properties. Besides, most plastics contain other organic or inorganic compounds blended in. The quantity of additives can be more than half for certain applications.

Additives in plastics

Plasticizers: Since many organic polymers are too rigid for particular applications, they are blended with plasticizers, the plasticizers are added to formulations to make them more flexible, tougher, or easier to manipulate, and confer improved rheology, dyes and paint are also common additives, for aesthetic considerations.

Fillers:

These improve performance or reduce production costs. Stabilizing additives such as anti-UV, help prevent or resist UV attack by sunlight, and flame retardants help lower the flammability of the material. In addition, many plastics contain fillers, relatively inert and inexpensive materials that make the product cheaper by weight [START_REF] Stenvall | Electronic Waste Plastics Characterisation and Recycling by Melt-processing electronic equipment with the objective of facilitating recycling[END_REF].

Hazard substances in flame retardants:

There are over 75 different Br compound families used as BFR (Brominated Flame Retardant), the BFRs are effective at delaying flame propagation, mainly due to the halogens which capture free radicals [START_REF]Observatoire Ré gional de la Santé de Rhône-Alpes[END_REF]. However, BFRs can increase the toxicity of fires through the release of byproducts such as brominated and chlorinated dioxins and furans during combustion. BFRs accumulate in human and animal bodies, the problem associated with their biodegradation in the environment is linked with the fact that they often contain aromatic compounds that are usually chemically resistant. The four main classes of BFRs, that are PBBs, PBDEs, hexabromocyclododecanes (HBCDs), and tetrabromobisphenol A (TBBPA), have been produced in large quantities in the past and are considered as "conventional", "typical", "legacy" "traditional" or "classical" BFRs [START_REF] Brossas | Retardateurs de flammes[END_REF]. Since a number of BFRs have been found to be persistent in the environment, legislative steps have been taken to discontinue their production. and other organic pollutants, such as polychlorinated biphenyls, hexachlorobenzene, toxaphene, etc,... [16][17].

Classification of plastics

Plastics can be classified by their chemical structure of polymer backbone and side chains, sometimes also by the chemical process used in their synthesis. Thermoplastics and thermosetting polymers (thermosets) are the two main types of plastic [START_REF] Maris | Mechanical recycling: Compatibilization of mixed thermoplastic wastes[END_REF].

Thermosets have a three-dimensional structure. The polymerization induces bridging macromolecules and, upon heating, this structure solidifies permanently to the desired shape. For the material obtained after implementation, the bonds between macromolecules are strong chemical bonds, this transformation is irreversible [START_REF] Mantia | Handbook of plastics recycling[END_REF]. So, thermosets can only melt and take shape once, after they have solidified, they stay solid and cannot be molded again.

Thermoplastics have an interlocked linear structure which does not result from polymerization.

During the shaping by heating, macromolecules fold then block during cooling resulting in solidification. For the material obtained after implementation, the bonds between macromolecules are weak physical Van Der Waals bonds, this transformation is reversible [START_REF] Plastics | Thermoset vs. Thermoplastics[END_REF]. They do not undergo a chemical change in their composition when heated and thus can be molded again and again. Because of their physical properties, thermoplastics are important in plastic recycling nowadays [START_REF] Osborne | The Difference Between Thermoplastic and Thermosetting Plastic[END_REF].

There are other types of plastic such as elastomers, biodegradable plastic, etc. An elastomer is a viscoelastic type of polymer with very weak inter-molecular forces, often used interchangeably with the term rubber. They are amorphous polymers existing above their glass transition temperature, thus relatively soft and deformable at ambient temperature. Biodegradable plastics are plastics that decompose by the action of living organisms, usually bacteria or flour, they break down upon exposure to sunlight, water or bacteria, enzyme, etc., without harm to environment.

In the context of recycling, it is necessary to have relatively large amounts of waste, and especially pure materials to be sorted because the sorting requirements are related to the problems of incompatibility of the polymer resins with each other during recycling. The recycling of incompatible materials leads to a mixed recycled material with degraded properties, which will have a negative effect on future applications with high added value.

It is advised to use compatible plastic materials in the same piece because the properties of recycled plastics fall rapidly if they are contaminated with small amounts of incompatible plastics. For example, without compatibilizing agent, the maximal tolerance of ABS within HIPS can be up to 4 wt% and impurity of PP within HIPS should be no more than 1 wt% [START_REF] Perrin | Influence of impurities on the performances of HIPS recycled from Waste Electric and Electronic Equipment (WEEE)[END_REF].

In the case that it is necessary to use incompatible plastics in the same piece, we must ensure that these materials could be easily separated for a disassembly phase, or, with sorting techniques becoming more efficient, they can be separated by physical-mechanical sorting after the grinding step of the part. Otherwise the unsorted plastics will be sent to energy valorization. The major problem is therefore to obtain a sufficiently pure sorted product. The purity of recovered material is essential during the recycling process, this is why the sorting step allowing the separation of plastics is a key step. In fact, the purer the phase, the easier its use in a recycling chain will be, and the better the quality of the recycled product.

Recycling of the plastic from WEEE 1.5.1 General context

Plastics account for a significant share of WEEE constituent materials, as mentioned before, 17% of treated WEEE is made from plastics, corresponding to 83.6 kt, and the quantities are growing steadily. The recycling of plastics is a challenge as there are so many families in polymers, each of them contains hundreds of different grades, pure or mixed. In addition, these polymers often contain additives (anti-UV, flame retardants, dyes, fillers, etc.). The aims of plastic recycling include environmental concerns, consumer demand, legislation and reduced costs compared to newly-produced material.

The benefit to the environment and the reduction in landfill capacity encouraged plastics recycling programs in most developed countries. The three essential points for successful plastics recycling are: a stable deposit involving sorting and reliable collection; an environment-friendly and economic recycling process which is definitely a very important credit in plastic recycling that is always compared to new-produced plastic; profitable products made from recycled materials.

Generally, there are two recycling processes: mechanical and chemical. The mechanical recycling transforms waste. Generally, the plastic is washed, crushed and remelted into pellets or new products. It does not change the chemical structure of polymer. The chemical recycling treats waste through decomposition. The polymers are decomposed and go back to initial monomers.

From the information above, we conclude that recycling and energy recovery are the main treatments of plastics from WEEE. Recycling (mechanical or chemical) is the most important and challenging step in waste equipment treatment (decontamination, dismantling, sorting) to obtain a high rate of clean plastic and "pure".

The plastic sorting treatment procedure

Manual sorting

In many cases, and for a large number of materials, after the material has been checked for conformity, this stage allows an initial waste sorting operation to be carried out, thus facilitating future automatic processing. Articles such as defective parts, scrap and off-cuts from industry, various polypropylene (PP), polystyrene (PS) and polyethylene (PE) products, collected postconsumption, are placed on belts and dismantled by operators who remove the coarsest pollutants (for example, rubber, screws and rivets from waste bin bags) and carry out an initial chromatic separation of materials. In some cases, simple visual verification is required before sending products to the different recycling lines.

Sink-float separation

The separation of different plastics or groups of plastic types based upon their different densities is probably the most cost-effective, high-capacity process in automated industrial separation for recycling plastic waste. Therefore, it is the most widely used method for plastic mixture separation in treatment centers. Such separations are relatively simple, easily automated and flexible in operation. When considering the weight of material treated industrially, it is globally the most widely used material separation process. In a few cases, density separation is a well-established method for producing finished plastic separations in situations in which there is a significant difference in density of the product in comparison with all other materials present, a density difference of at least 0,10g/cm is demanded [START_REF]Eco3e[END_REF]. With the differences of density showed in figure 1234567, separations of a given type or group of plastics could be accomplished, such as separating most of the PC from PP and PE, or separating most of the PP from PMMA, PC and PVC. Such separations are based on a float/sink process in which particles of different density are placed within a medium of intermediate density. Lower density particles float, whereas those of higher density sink at rates corresponding to their relative buoyancy in the medium under the force of gravity. Other factors affecting whether fragments of two or more plastics of different densities can be separated effectively in industrial processes include: particle form, size and surface texture; viscosity of the medium; contrast in density with the medium; adherence of particles; agglomeration of droplets or bubbles with particles; hydroscopic resistance of plastics to sinking when at an air-water interface; and the rate at which they must be separated for the process to be economically viable.

As particle surface area increases exponentially relative to mass with reduction in particle size, so does their resistance to movement in the medium. Density separations are thus faster and more effective in separating larger particles of slightly different densities than they are for finer particles.

For particles that are non-spherical, such as fragmented plastics, the rate of displacement of particles of the same density and mass in a medium also varies with particle surface roughness and form. Substances regularly used to regulate the liquid medium density are CaCl2, NaCl, CaNO3, alcohol, etc.

Optical sorting

The optical sorting recognizes different types of polymers comparing their spectra in the near infrared (NIR) range with a library of reference spectra. The main limitations are linked to: (i) separation efficiency, depending on the size of plastic flakes (good detection is usually achieved for particles with size >5 cm), (ii) sensing unit "blindness", depending on flakes color (dark plastics, for their low reflectance, are not classified), (iii) flakes surface status (the presence of labels, dirtyness or paint and coating on the plastic surface does not allow a correct recognition)

For these reasons about 50% of the input material is not correctly separated and ends up in the residues, which are usually send to incineration [START_REF] Serranti | An innovative recycling process to obtain pure polyethylene and polypropylene from household waste[END_REF].

Tribo-electrostatic separation

An important indicator for the separation is the triboelectric series of the polymers. This series describes the acquired polarity of the charged plastic particles. In this way, it is possible to rapidly predict the polarity of the charge for the recycling of plastic wastes using tribo-electrostatic separation [START_REF] Li | Tribo-charging properties of waste plastic granules in process of tribo-electrostatic separation[END_REF].

After the tribo-charging process, the different materials will acquire electric charges with different polarity (positive, negative, or neutral), enabling the collection of each material in a separate collection box, depending on the charge [START_REF] Wu | Triboelectrostatic separation for granular plastic waste recycling: A review[END_REF]. The particles are collected in three different compartments, as shown in Fig. 12345678. Negative particles remain adhered to the roll and are collected in the first collector. Neutral particles are collected in the second collector, while positive particles are attracted to the electrostatic electrode and will be collected in the third collector [START_REF] Silveira | Application of triboelectrostatic separation in the recycling of plastic wastes[END_REF]. After a certain period of frictional charging time, the oppositely charged plastics fall down freely in the area between the electrodes. The particles are drawn either to the positive or negative electrode according to the polarity of the charge, and separated by falling into different collecting bins.

From the information above, plastic is a very flexible material, it is based on different families of polymer, different additives are added in its production, which leads to a diversity of plastics, especially in the end of life product. As explained before, to achieve the required recycling rate, the plastic needs to be separated into all polymer families before regeneration. Due to their different properties, there is no single method of plastic sorting and a combination of procedures is more effective.

In the treatment plants, the different types of plastics are sorted mainly by two technologies, optical sorting and sink-float separation [START_REF] Serranti | An innovative recycling process to obtain pure polyethylene and polypropylene from household waste[END_REF]. The former recognizes different types of polymers based on their spectra in the near infrared (NIR) range. The limitation of the method mainly due to flake colors (dark colored plastics with the low transition). Sink-float processes separate different materials based on their different densities. These techniques use a process medium with an intermediate density between those of the polymers to be separated. Usually sink-float separation is simple but problems occur if the materials' densities are too close.

For the reasons above, we will investigate the following technology, which is independent of plastic colors, and is less influenced by similar densities of plastic.

Separation by flotation 1.6.1 Froth flotation in plastic separation

Flotation was originally developed by the mineral industry for ore separation at the beginning of the 20 th century, then adopted by mineral researcher for use in the plastic recycling industry in the 1970s. The application of flotation separation to plastic mixtures is relatively new, and was once popular in late 20 th century generating a lot of research. However, in the last ten years, research enthusiasm has decreased as other separation methods like optical separation and tribo-electricity separation have been developed.

Plastic flotation exhibits a number of specific features compared to mineral flotation. These features are related to the distinct properties of plastics: such as low density; low surface energy, etc. An important consequence is that the size of plastic particles that can float is significantly large than the floatable size of ore grains [START_REF] Fraunholcz | Plastics Flotation[END_REF].

Separation by flotation depends mainly on the hydrophobic and hydrophilic properties (natural or induced) of surface particles. Air bubbles are introduced into the aqueous phase, they adhere to the more hydrophobic particles, then rise to the surface. Particles that are more hydrophilic remain at the bottom of the cell. This will be discussed in more detail in the chapter on flotation study.

The crucial point in achieving separation by flotation lies in defining a suitable surface treatment method to obtain selective bubble attachment on the components to be separated. As bubble attachment is a dynamic process, the control of physical parameters to evaluate the floatability of the particles became more and more important. In the majority of studies on plastics flotation, flotation recovery was used to describe this phenomenon [START_REF] Guern | Role of calcium ions in the mechanism of action of a lignosulphonate used to modify the wettability of plastics for their separation by flotation[END_REF][33] [34][35][36] [START_REF] Wang | Floatability of polymer materials modulated by frothers[END_REF].

The recovery of plastic samples is an indicator of floatability, because it is determined by the simultaneous influence of the hydrophobicity and specific surface area of the particles, but flotation recovery data obtained in different types of flotation cells may be difficult to compare, due to different hydrodynamic conditions in the device applied, different cell dimensions might have different result. Even one condition works excellently in one cell, the result might not be as good as before when the dimension becomes larger. In addition, the evaluation of the separation results of flotation tests can be difficult and time consuming.

In recent years, many experiments were also conducted on the contact angle since it is the most direct method [START_REF] Mallampati | Selective sequential separation of ABS/HIPS and PVC from automobile and electronic waste shredder residue by hybrid nano-Fe/Ca/CaO assisted ozonisation process[END_REF][39][40] [START_REF] Maſko | Wettability prediction of such polymers as polyethylene and polytetrafluoroethylene by aqueous solutions of classical surfactants and biosurfactants[END_REF]. The only thesis on flotation separation of plastics in France is the thesis of Le Guern [START_REF] Guern | Séparation de déchets de plastiques par voie physico-chimique (flottationmoussage) en vue de leur recyclage : applicabilité au mélange PVC/PET bouteilles[END_REF], the author worked on the separation of mixture of PVC and PET using different surfactants, and found that the receding contact angle reflects the flotation response of mixtures of PVC and PET flakes treated in a surfactant solution, better than the advancing contact angle. The author also demonstrates that PET flakes were depressed to 99.8% in flotation if the receding contact angle obtained by surfactant adsorption is about 30°.

Important parameters during conduction of flotation separation

The parameters used to optimize the efficiency of separation are listed below. Among the various parameters, absorption is the principal factor to control, while other factors such as the size of the particles must also be taken into account [START_REF] Biddle | Recycling the Hard Stuff[END_REF]. These variables can affect the form of the absorption, break the hydrophobic film and the superficial roughness. Finally, they influence the key stage, which is the attachment of bubbles and particles.

-

The airflow rate injected into the flotation cell The airflow rate (L/min) changes the amount of bubbles that the system generates, introducing greater kinetic energy and movement into the solution which causes instability in the process and in maintaining bubble-particle contact. Matteo et al. applied different speeds to study the influence of airflow rate according to flotation kinetics. They assumed that all the other variables were kept constant and, since frother concentration was constant in both situations, the increase in air flow rate may have led to larger and weaker air bubbles, preventing the particles from being transported to the surface of the flotation cell [START_REF] Censori | Separation of plastics : The importance of kinetics knowledge in the evaluation of froth flotation[END_REF].

-The size of particle Factors determining the average density of a bubble-plastic particle aggregate are the distribution of the attaching bubbles, the fraction of the particle surface covered by bubbles, the density and size of the particle as well as its specific surface area. Since the specific surface area of a particle depends on its shape, it can be deduced that the floatability of plastic particles is related to particle shape. The common view of particle size is limited to 2-6mm depending on plastic densities, as particle size is related to specific surface area, which is a parameter of intermolecular forces. Reducing particle size leads an increase in the specific surface area of particles, and hence the bubble coverage that is needed for flotation declines with particle size. The bubble-particle aggregate will rise to the liquid surface if its average specific gravity is lower than the density of the liquid, unless external influences, such as a strong liquid flow, overpower the buoyancy of the ascending aggregate.

-The temperature The temperature in the solutions is also a variable that has been analyzed in the investigation, to determine the positive or negative variations in the flotation process. Wang et al. proposed a new method for separation of ABS and PS, which is a combination of boiling treatment and froth flotation. Boiling treatment was effective in producing a hydrophilic surface on ABS plastic, and the mechanism was explained by surface rearrangement. The selective influence of boiling treatment on the floatability of boiled treated plastics may be attributed to the difference in the molecular mobility of polymer chains. Flotation separation of ABS and PS plastics with different particle sizes was efficiently achieved combined with boiling treatment [START_REF] Wang | Boiling treatment of ABS and PS plastics for flotation separation[END_REF] [START_REF] Guney | Investigation of thermal treatment on selective separation of post consumer plastics prior to froth flotation[END_REF].

-The pH regulation The pH value of the solution must also be analyzed, as it affects the superficial tension of the solutions and it may influence the selection and separation of plastic particles, in acid, neutral and basic solutions.

-Geometric cell dimensions Another important factor is the geometry of the cell, since the flow of the bubbles and the movement that this generates across the surface change when the cell geometry is changed. If a cell rectangular or a cylindrical cell is used, the movement will change the solution from laminar flow to turbulent flow. In addition, it depends on the volume and the final height of column.

-Surface treatment The mechanism of surface modification can be chiefly explained by surface oxidation, which results in grafting hydrophilic functionalities such as hydroxyl, carboxyl and carbonyl onto the polymer chains located on the surface [START_REF] Basařová | The influence of flotation agent concentration on the wettability and flotability of polystyrene[END_REF]. Numerous methods are available to increase the hydrophilic degree of plastics surface, such as ozonization, plasma treatment, corona discharge and photo grafting [START_REF] Reddy | Selective recovery of PVC-free polymers from ASR polymers by ozonation and froth flotation[END_REF][39] [START_REF] Srinivasa | Surface ozonation of polyvinyl chloride for its separation from waste plastic mixture by froth fl oatation[END_REF]. Alkaline solutions are the most widely used to facilitate the removal of labels and glue from plastics surface, and are often applied to clean plastics. Since sodium hydroxide breaks the ester bonds in PET, alkaline treatment can be employed to make PET surfaces selectively wettable, and flotation separation of PET from other plastics was achieved combined with alkaline treatment [START_REF] Saisinchai | Separation of PVC from PET/PVC mixtures using flotation by calcium lignosulfonate depressant[END_REF][51][52] [START_REF] Wang | Flotability and flotation separation of polymer materials modulated by wetting agents[END_REF]. Similarly, PC is sensitive to ammonia solution, and thus ammonia treatment can be applied to separate PC by flotation from plastics that are insensitive to ammonia treating [START_REF] Wang | Separation of PC and ABS waste plastics by froth flotation combined with ammonia pretreatment[END_REF].

Adsorption and reagents applied

As plastics belong to low surface energy solids, wetting by water can be achieved though lowering the liquid surface tension by adding an appropriate surfactant (reagent). However, it is difficult to provide sufficient selectivity since the difference between the surface free energy of different plastic types is rather small. Adsorption of hydrophilic reagents is then a promising alternative and surfactants are widely used in ore flotation to increase the hydrophilic character of solids.

Suitable surfactants for the flotation of plastics are composed of molecule parts that are capable of adsorbing on plastic surfaces and also of molecular groups that render the particles hydrophilic. The concept of hydrophobic and hydrophilic properties of surface has one major importance in the comprehension of the elementary phenomenon of flotation, which is the contact between a bubble of air and the surface of a solid in a liquid. As simply shown in figure 1-9 below. In ore flotation, the solid particles are normally much smaller in comparison with air bubbles. The particle size of solids ranges between about 30 and 1000 µm, whilst air bubbles are up to 1.5 mm in diameter. Therefore, a single bubble is capable of carrying several solid particles during flotation [START_REF] Wang | Flotation separation of waste plastics for recycling-A review[END_REF]. However, plastic particles subjected to separation are usually several millimetres in size. As a result, numerous bubbles will attach to one particle during flotation.

A series of surfactants that are suitable for plastics flotation have been reported, such as tannic acid [START_REF] Shibata | Flotation separation of plastics using selective depressants[END_REF][56] [START_REF] Reddy | Selective recovery of PVC-free polymers from ASR polymers by ozonation and froth flotation[END_REF], methylcellulose [START_REF] Shen | Selective flotation separation of plastics by chemical conditioning with methyl cellulose[END_REF] and lignosulfonates [START_REF] Wang | Effects of additives on PVC plastics surface and the natural flotability[END_REF], and numerous studies have been conducted to investigate the action mechanism during the past two decades [START_REF] Wang | Flotation separation of waste plastics for recycling-A review[END_REF] [START_REF] Shent | A review of plastics waste recycling and the flotation of plastics[END_REF].

The suggested adsorption model is shown in figure below. Fraunholcz et al. [START_REF] Fraunholcz | Wetting mechanisms in the flotation of plastics[END_REF] studied the mechanisms of the adsorption of depressants on plastics and suggested the following mechanisms: 1. The adsorption of depressants on plastics is mainly driven by physisorption. 2. The interaction forces include hydrophobic interactions and electrostatic forces. Hydrogen bonding is not involved in the adsorption on plastics. 3. Zeta-potential measurements indicate a non-selective adsorption of surfactants on most types of plastics, although selective bubble attachment to different plastics occurs during flotation. 4. The intrinsic surface polarity of plastics appears to play an important role for the resulting overall effect of depressants. Fraunholcz's work [31][33][59] on flotation is well-known in Europe, he investigated the mechanisms of the adsorption of surfactants on plastic surfaces and suggested the mechanisms: the adsorption of wetting agents on plastics is mainly driven by physisorption; the interaction forces include hydrophobic interactions and electrostatic forces; non-selective adsorption of surfactants occurs on most types of plastics, but bubbles attach selectively to different plastics during flotation; the intrinsic surface polarity of plastics plays an important role for the effect of wetting agents; metal ions reduce the repulsion between the charged segments of polyelectrolytes, facilitating adsorption, and modify the segment-surface electrostatic interactions [START_REF] Wang | Flotation separation of waste plastics for recycling-A review[END_REF].

Wang et al. [START_REF] Wang | Floatability of polymer materials modulated by frothers[END_REF][60] [START_REF] Wang | Wetting behavior and mechanism of wetting agents on low-energy surface[END_REF] studied the interactions between different phases in plastics flotation systems, involving van der Waals force, Lewis acid-base interaction and hydrogen bonds. Through a study of wetting behavior of plastics and adsorption mechanisms of reagents, adsorption models of reagents on plastic surface were proposed. The hypothesis is that, adsorption of wetting agents on polymer surface was achieved through hydration shell, interactions between wetting agents and plastic surface involve mainly van der Waals force, Lewis acid-base force, electrostatic force and hydrogen bonds were presented, and that adsorption of wetting agents is driven by these interactions [START_REF] Wang | Flotation separation of waste plastics for recycling-A review[END_REF].

Surface treatment

Surface pretreatment is largely studied these years since it is possible to improve the separation, since surface treatment is more reliable and requires less chemical reagents, which reduces the problem of waste water. While it should be noticed that no toxic matters can be generated in the flotation process. [START_REF] Wang | Separation of polyethylene terephthalate from municipal waste plastics by froth flotation for recycling industry[END_REF] and ammonia treatment [START_REF] Wang | Ammonia modification for flotation separation of polycarbonate and polystyrene waste plastics[END_REF], and the mixture of plastics are successfully separated with high purity.

Wang et al. did a lot of experiments on surface treatment before the flotation, for example, pretreatment of plastics with potassium permanganate (KMnO4) solution was conducted to aid flotation separation of polycarbonate (PC), polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA) plastics [START_REF] Wang | A novel process for separation of polycarbonate , polyvinyl chloride and polymethyl methacrylate waste plastics by froth flotation[END_REF] because potassium permanganate changed selectively the flotation behavior of plastics through oxidization action, and assure the separation of plastics by the following flotation. It is justified that surface treatment does not change the molecular structure of PC, PVC and PMMA, implying that the quality of separated plastics will not be affected. The purity of PC, PVC and PMMA is up to 100%, 98.41% and 98.68%, and the recovery reaches 96.82%, 98.71% and 98.38%, respectively. They also applied potassium ferrate solution to conduct the surface treatment, aims at the separation of PC and PS plastic mixture [START_REF] Wang | Surface treatment using potassium ferrate for separation of polycarbonate and polystyrene waste plastics by froth flotation[END_REF]. The purity of PC and PS reaches 100.00% and 99.54%, and the recovery of PC and PS is more than 95.60% and 100.00% respectively. In this study they have also considered the reuse of waste water and potassium ferrate solution. It is a very promising direction to take into account the reuse of resources under the trend of circular economy and ecology. In addition, Calcium hypochlorite [START_REF] Wang | A novel process for separation of hazardous poly(vinyl chloride) from mixed plastic wastes by froth flotation[END_REF] and Fenton treatment [START_REF] Wang | Fenton treatment for flotation separation of polyvinyl chloride from plastic mixtures[END_REF] was developed for flotation separation of PVC from plastic mixtures.

Conclusion

The previous litterature review showed that plastics waste has become one of the largest sectors in WEEE. Plastics recycling is important to the plastic industry, to energy saving and the environment. The state of the art of plastics in WEEE and flotation separation literature was presented and reviewed. Flotation is a promising method for separation of waste plastics according to previous review, and this technology is receiving increasing attention for recycling of plastics. Among the sorting technologies in plastic separation, this technology is able to separate dark colored plastics, which is a very important and interesting point in WEEE plastic sorting. For the reasons mentioned above, in this thesis, the flotation is chosen to be studied and discussed in further details. The benefit of the application of flotation will be discussed in the following chapter with an MFA study.

Chapter Material Flow Analysis case study of plastic management 2.1 Introduction of MFA (Material Flow Analysis)

The MFA methodology is an analytical method for quantifying flows and stocks of substances or substances in a well-defined system, a systematic resource management system, a systematic reconstruction of the path a material takes through the natural and/or economic cycle [START_REF] Parajuly | Waste electrical and electronic equipment (WEEE) in Denmark: Flows, quantities and management[END_REF][72] [73][74]. This is used to study flows of materials, substances or products in different industrial sectors or within ecosystems [START_REF] Bahers | Regional approach of waste electrical and electronic equipment (WEEE) management in France[END_REF]. When dealing with MFA, one should respect the principle of physical balance. Its application is very useful for studying the circular economy and achieving good material flow management, for example, it has been used as a means to quantify the input and output of harmful substances through the production process and supply chain [START_REF] Kim | Experimental Investigation on Electrochemical Properties of Ionic Polymer-Metal Composite[END_REF].

WEEE management in France

Modeling and analysis

In France, the collection and treatment of WEEE started following the EU directive 2002/96/CE [START_REF]EUR-Lex. EU directive for WEEE[END_REF]. It first began in 2005 for industry and then in 2006 for households. This directive also implies that every manufacturer of EEE should inform the ADEME agency about every input flow in the French market [START_REF] Ademe | SYDEREP-ADEME[END_REF]. This allows better traceability of equipment and their EoL issues.

More specifically, data for SHA's evolution of the total tonnage from 2006 to 2016 are presented in Fig. 2-1: As shown in this figure, SHA collection and treatment is growing constantly. These quantities have reached 39441 tons collected and 40222 tons treated in 2016. The treated quantity is higher than the collected quantity for the same year, due to the collected SHA stock waste cumulated from previous years.

In this study, we will only focus on the collection, treatment and End of Life issues of SHA plastics, which has reached 20.2% of the total quantity of generic SHA equipment [START_REF]Flux DEEE_PAM[END_REF]. In order to estimate and assess plastic flows generated from SHA in France from 2006 to 2016, an MFA model has been used. We thus used STAN computer software to map out the results [START_REF] Cecnic | Material flow analysis with software STAN[END_REF]. In this study, MFA was used to quantify plastic materials from SHA and their EoL issues, it helps trace waste and flows to the point they were generated in order to identify weak points and possible solutions.

According to the SHA data gathered, the following rates of treatment and sorting were considered to model all the input and output flows. Firstly, the plastic materials from all input flows of SHA represent 20.2% of total weight [START_REF] Maris | Mechanical recycling: Compatibilization of mixed thermoplastic wastes[END_REF]. In this study, we will consider that the other 79.8% of other materials is collected and disposed of via other recycling processes and plastics with bromine flame retardant (BFR) in SHA will be disposed. In this study, these rates will be considered the same for SHA inputs from 2000 to 2016. Non-brominated plastic flows go through firstly the sink-float separation, contain plastics with similar density, up to 29% of ABS, 26% of HIPS and 4% talc filled polypropylene, the talc filled polypropylene account for 18% of all the polypropylene in SHA [START_REF] Maris | Characterizing plastics originating from WEEE : A case study in France[END_REF].

Thus, the non-recycled quantities of SHA are still considerably increasing in recent years, and the current sorting and recycling processes have difficulties with these flows since they have similar density and dark colored. For this reason, we present in this paper a novel sorting technique for WEEE plastics. This technique has proven to be efficient when dealing with major plastic sorting. Furthermore, we incorporate this technique into an MFA for SHA to generate the increase of sorting and thus recycling flows of SHA plastics.

For the purpose of this study, we also include traditional sorting and recycling techniques. At this step, we consider that 59% of SHA plastics are light colored, the rest is considered as dark color plastics [START_REF] Maris | Characterizing plastics originating from WEEE : A case study in France[END_REF]. Light color plastics will be sorted using the optical sorting technique and dark colored ones are sorted using sink float separation. The sorting looping rates are 90% and 95%, respectively (feedbacks from discussion with French industry).

The next section presents the results of the material flows and EoL SHA plastics in France from 2006 to 2016.

Results and discussion

When grouping all the data of SHA generated in France from 2006 to 2016, 1,701,670 tons of SHA from the total 15,521,666 tons of EEE was injected into the French market (the imported and exported flows from outside the French perimeter were not taken into consideration), while 259,754 tons of waste SHA were collected from 2006 to 2016. From these flows, only 257,723 tons of waste were considered as treated in this period [START_REF] Deprouw | Rapport Annuel du registre des déchets d'équipements électriques et électroniques -Données 2016[END_REF]. Several assumptions were made about the non-collected and treated flows. The major ones consider that SHA are generally reused (second hand), disposed in households or still in use considering their lifetime distribution. In this study case, we apply the MFA under two scenarios where the novel sorting technique is introduced.

Let us start with the scenario where the new flotation technique is not considered. In this case, dark color plastics are sorted by sink-float separation and plastics with similar density are collected as unrecycled plastics.

As seen in figure 2-2, if we do not consider the new flotation sorting technique, only 3,255.09 tons of plastics could be recycled by sink-float separation and optical sorting from 2016 flows. However, when we consider the proposed new technique as mentioned above, this technique helps to increase a recovery of 30% plastics based on the results from experimental tests, the recycled flows increase to 3917.35 tons instead of 3255.09 tons, thus the unrecycled flows decrease to 1578.29 tons instead of 2240.55 tons. Thus, with the help of flotation separation, the recycled rate of SHA plastic without flame retardant bromine is improved from 52.7% to 63.4%. Figure 23shows that dark color plastics with similar densities can be partly sorted using this method.

Conclusion

In this case study, a novel method based on the flotation technique was presented and included in a material flow analysis of SHA plastics. Experimental data proved that this technique's efficiency is up to 30% when dealing with dark color plastics of similar density (talc filled PP, ABS and HIPS), which are difficult to treat using traditional methods. Consequently, when this technique is incorporated into a material flow analysis, results showed that the recycled flows are increased.

Moreover, the simplicity of this method allows it to be easily implemented in existing DEEE plastics sorting and recycling facilities. Even though, in this study, the flotation technique was experimented on small household appliances, we believe that it can be extended to other categories.

Chapter Choice of plastic from WEEE and selection of surfactants for experimentation forwards to flotation

Choice of plastic materials in experiments

In this research, we chose three plastics, ABS, HIPS and PP filled with 20% talc. As mentioned before, we consider flotation separation as a complimentary sorting method, so we focus on the dark plastics with similar density (more than 1000kg/m 3 ) based on the following criteria: 1). Plastics with similar density assure that these plastics cannot be separated by sink-float flotation.

2). Plastics with density more than 1000kg/m 3 naturally sink in water so that we change the liquid condition to obtain a selective separation, if their density is less than 1000kg/m 3 , then all of them will float to the surface and it will be impossible to achieve the separation.

3). Compared with the traditional optical sorting, which cannot handle dark color plastics, colors have no effect flotation separation. Therefore, we can deal with dark color plastic in our research, which is an obvious advantage of this technique.

In addition, according to an ADEME report [START_REF] Outils | Rapport Final AJI[END_REF], ABS, PS and PP are the plastics most used in DEEE. Previous studies of the plastics composition of WEEE have also reported the major constituents to be these three plastics [START_REF] Dimitrakakis | Small WEEE: Determining recyclables and hazardous substances in plastics[END_REF][81] [START_REF] Martinho | Composition of plastics from waste electrical and electronic equipment (WEEE) by direct sampling[END_REF]. In this case, dark colored ABS, PS and PP filled with 20% talc were chosen in this study.

-ABS Acrylonitrile butadiene styrene (ABS) is thermoplastics. It is an amorphous polymer that is manufactured following the emulsion or bulk polymerization of acrylonitrile and styrene in the presence of polybutadiene [START_REF] Lamarti | Evaluation of Damage by the Reliability of the Traction Test on Polymer Test Pieces[END_REF]. The chemical formula of these 3 monomers is given in the following figure. The styrene monomer gives ABS a good processability, acrylonitrile provides stiffness as well as thermal and chemical resistance, and finally butadiene makes the ABS harder, but elastic, even at low temperatures (-40 ° C) [START_REF] Beccari | Thermoplastic styrenic polymers[END_REF]. ABS has good resistance to chemical attack [START_REF] Beccari | Thermoplastic styrenic polymers[END_REF]. In fact, it is resistant to aqueous acids, bases, concentrated hydrochloric and phosphoric acids, most alcohols and animal, vegetable and mineral oils. On the other hand, it is attacked by concentrated sulfuric and nitric acids and is soluble in esters, ketones, ethylene dichloride or acetone. It is preferred for indoor use as it is sensitive to UV rays and weathering but is possible to incorporate additives into the composition of the material to correct these elements. ABS can be processed by injection molding or extrusion molding processes. It lends itself well to the techniques of welding or gluing plastics. It can support several decoration techniques: painting, printing, metallization, hot stamping and coloring in the mass.

Due to the qualities mentioned above: lightness, impact resistance, dimensional stability and its suitability for decoration, ABS is used in the following industries / applications:

• General public: toys, consumer goods, telephones, safety helmets • Automotive: interior door panels, uprights, seat trims, grilles, dashboards, mirror housings • Appliances: kitchen appliance covers, vacuum cleaner housings, white goods control panels • Extrusion: sheets, shower trays, tractor roofs, furniture carols, refrigerators, luggage. "

Virgin ABS is a bit expensive, so the recycling solution is very interesting economically speaking because the recycled ABS can be mixed with the virgin material to ensure qualitatively correct properties at low cost.

-HIPS HIPS is a grafted copolymer of cis-1,4-poly(1,3-butadiene) and styrene monomer [START_REF] Fryling | High impact polystyrene[END_REF]. The double bonds in the polybutadiene allow the graft polymerization to occur when polymerized with styrene monomer. The chain structures of HIPS repeating units are presented in figure 3-3. As far as its chemical properties are concerned, HIPS has excellent resistance to bases and hydrocarbons, but not to acids. Resistance depends on several factors, including concentration, temperature and time of exposure to solvents. As HIPS has a good balance between rigidity and mechanical strength, it gives us more possibilities of transformation processes such as injection molding, extrusion, thermoforming. It is suitable for assembly by welding, machining or gluing. Aspect changes are also possible (paints, varnishes, metallization). Thanks to its good performance, HIPS is used in many fields.

▪ Food and related packaging ▪ Enclosures for CDs, audio and video cassettes, DVDs ▪ Appliances (external parts of washing machines, etc.) ▪ Consumer electronics (television facades, office equipment)

-PP filled with 20% talc PP is very popular as a high-volume commodity plastic [START_REF] Kant | Study of talc filled polypropylene-A concept for improving mechanical properties of polypropylene[END_REF]. However, it is referred to as a lowcost engineering plastic. PP offers good fatigue resistance, good chemical resistance, good environmental stress cracking and is compatible with many processing techniques so that it used in many different commercial applications. The low cost and high thermal and mechanical properties of PP compared to other thermoplastics such as polyethylene contribute to its strong growth rate. It is one of the lightest of all thermoplastics. In particular, due to its high strength to weight ratio, it is more rigid than other polyolefins [START_REF] Wang | Characterization and modeling of the thermomechanical behavior of polypropylene-based composites : effect of recycling and filler content[END_REF]. The following table summarizes the main characteristics of PP: PP is a widely applicable polymer material because of its many advantages such as easy processability and low production cost. However, its application has been limited due to its relatively poor stiffness. A composite with mineral has been considered a useful way to improve the stiffness. In this case, talc is used as a mineral additive. The PP/talc composite has been widely studied by many researchers [START_REF] Beuguel | Influence of formulation on morphology and rheology of polypropylene/polyamide blends filled with nanoclay mineral particles[END_REF]- [START_REF] Ghasemi | Optimization of mechanical properties of polypropylene/talc/graphene composites using response surface methodology[END_REF].

Talc is a hydrated magnesium sheet silicate with the chemical formula Mg3 Si4 O10 (OH)2. Talc is practically insoluble in water and in weak acids and alkalis. It is neither explosive nor flammable although it has very little chemical reactivity. Polypropylene filled with talc shaped by both injection and molding, is generally used for structural applications. Generally, the typical loading of talc in PP matrix is in the range of 10% to 40% (wt.%). Talc filled grades offer higher stiffness, better surface aesthetics, a lower coefficient of thermal expansion, and improved scratch and heat deformation resistance than non-filled grades. Heat deflection temperature and mold shrinkage are also improved by the addition of talc. Extensively used applications for talc filled polypropylene are automotive, electric equipment and other industrial components, such as under-the-hood automotive parts, appliance shells, and thermoformed packaging products including microwaveable products [87][92].

-Bromine flame retardant (BFR) Brominated flame retardants (BFRs) belonging to different chemical families have been widely incorporated into consumer products to make them less flammable. The most used, which represent 30% of flame retardants on the market in Europe, are: polybrominated diphenyl ethers (PBDEs) used in plastics, textiles, electronic molds, and circuits; hexabromocyclododecanes (HBCDD) in thermal insulation in the building industry; tetrabromobisphenols A (TBBPA) and other phenols in printed circuit boards and thermoplastics; polybrominated biphenyls (PBB) in household appliances, textiles, and plastic foams [START_REF]Observatoire Ré gional de la Santé de Rhône-Alpes[END_REF].

Tetrabromobisphenol A (TBBPA) is one of the most frequently used BFRs. Its importance is based on the demand for substitution of additively incorporated polybrominated diphenylethers and biphenyls [START_REF] Wichmann | Thermal formation of PBDD/F from tetrabromobisphenol A--a comparison of polymer linked TBBP A with its additive incorporation in thermoplastics[END_REF]. Figure 3-6 shows the structural formula of TBBPA.

Surfactant agents applied in experiments

The flotation experiments, the surfactants are used as reagents to make plastic mixture separate, so the type of surfactants is a very important element. It is with surfactants that the flotation is able to work. Thus, the selection of surfactants is necessary. Since the wettability tests is a previous step for selection of surfactants, surfactants are pre-used in this part of experiment.

In wettability tests, we use several surfactants at different concentrations to modify the hydrophobicity of plastic surface, the objective is to select the appropriate surfactant for the flotation experiment, by observation of the contact angle of surfactants on different plastics. The dimension of contact angles is possible to indicate whether the plastic surface is wet by surfactants.

In addition, this part of experiments is possible to observe the influence of materials' properties, such as types of materials and their surface conditions which will be discussed in further details with the results from wettability tests.

Sodium Carboxymethyl Cellulose (NaCMC)

The sodium salt of carboxymethyl cellulose (NaCMC) is a linear unbranched polysaccharide (figure 3-7 below), a derivative of the ubiquitous natural polysaccharide cellulose. It is produced by aqueous alkali reaction with monochloroacetic acid in organic solvent [START_REF] Sunardi | Preparation of carboxymethyl cellulose produced from purun tikus (Eleocharis dulcis)[END_REF]. NACMC is an odorless, water soluble, granular powder and its color varies from white to almost white. NaCMC is a useful derivative of cellulose with various valuable application in the detergents, paper, food, pharmaceutical, and cosmetics industries [START_REF] Khaled | Rheological and electrokinetic properties of carboxymethylcellulosewater dispersions in the presence of salts[END_REF].

Methyl cellulose (MC)

Methyl cellulose is a chemical compound derived from cellulose. In its pure form, it is a watersoluble white powder, when dissolved in water it forms a clear viscous solution or gel. It is an important commercial cellulose ethers and it has been used in many industrial applications [START_REF] Data | Culminal TM methylcellulose derivatives[END_REF].

MC is one of the several cellulose derivatives which are commonly used as organic depressants or flocculent in mineral flotation [START_REF] Shen | Selective flotation separation of plastics by chemical conditioning with methyl cellulose[END_REF].

MC is the simplest cellulose derivative, where methyl groups (-CH3) substitute the hydroxyls at C-2, C-3 and/or C-6 positions of anhydro-D-glucose units. (figure 345678) PVA is widely used in many industrial applications such as for textile sizing, adhesives, protective colloids for emulsion polymerization, production of PVA fibers and polyvinyl butyral and paper sizing [START_REF] Marten | Vinyl alcohol polymers[END_REF]. It can also be used in medical and food applications [START_REF] Julinová | Water-soluble polymeric xenobiotics -Polyvinyl alcohol and polyvinylpyrrolidon -And potential solutions to environmental issues: A brief review[END_REF]. Fig. 3-10 illustrates the production outline of PVA.

Experimental approach

We conducted two experiments during this research: the wettability experiment and the flotation experiment. The aim of the wettability experiment is to study the influence of different surface conditions (oxidation on plastics, the addition of additives such as bromine flame retardant and talc) and to find suitable surfactants with their condition for the following flotation experiment. Different plastic samples were used in these two experiments. Therefore, the preparation of the samples consists of two parts: the preparation for wettability experiment and the preparation for flotation experiment. For wettability experiment, samples are prepared in terms of material, additives and thermal oxidation.

Preparation of materials for flotation experiments

The plastic samples were collected by two ways: the non-used plastics from local treatment center and waste plastics from a local WEEE dismantling plant. The different plastics were selected in different colors to distinguish the different types in the experiments, in which all the plastics were mixed in the column.

Because the plastics from WEEE equipment were too big to conduct experiment, we firstly cut them into smaller pieces about 15mm*15mm by a chainsaw. Then, we can get the particles by crushing the 15mm*15mm pieces with a Wanner Technik 14.13 EZ-SS shredding machine equipped with a sieve of 10 mm. After that, the particles were classified by sieving into different sizes. Finally, we can obtain homogeneous batches for flotation tests.

We did not dissolve the powder directly in flotation column as it occupies the use of the cell and also it is not clear to check if the surfactant powder was completely dissolved because of the large volume. Thus, the preparation of surfactant solution is in parallel.

Preparation for wettability experiment

The objective of the wettability experiment is to observe the performance of surfactant agent liquids on different materials, in the basis of which we can investigate the function of three criteria, 1) the addition of BFR, 2) the thermal oxidation at 90℃ in 12 hours, and 3) types of polymers.

Design of experiments

The samples used in wettability experiments are square pieces of ABS, HIPS and PP, which are divided into two parts: samples with additives and samples without additives.

On some of the ABS and HIPS samples we carried out thermal oxidation. Therefore, we can get 8 different types of samples, as shown in Table 3-3.

BFR Non BFR Oxidation Non oxidized ABS S1 x x S2 x x S3 x x S4 x x HIPS S5 x x S6 x x S7 x x S8 x x PP S9 x S10
x ABS group and HIPS group follows these two parameters, the addition of bromine flame retardant (BFR) which is TBBPA at 15% and thermal treatment. For example, S1 is untreated ABS, without addition of TBBPA, S2 is ABS with 15% TBBPA added and not oxidized, S3 is ABS without addition of TBBPA and treated with thermal aging, S4 is 15% TBBPA filled ABS treated with thermal aging.

Again, the same grouping and order for samples based on HIPS corresponds to S5 -S8. PP samples were not oxidized, they were only divided into two parts, one with 15% TBBPA (S9), the other without addition of TBBPA (S10).

Next, in order to observe the effect of talc content in PP, a series of samples were tested, S9 is neat PP without addition of BFR, S11 is PP filled with 10% talc, S12 is PP filled with 20% PP. In addition, three surfactant agents were used in the experiments: 1) MC 2) NaCMC 3) PVA. They were firstly weighed using a KERN AES 220-4 balance (d=0.0001g) and then dissolved in deionized water with the help of a Fisher brand 10510 magnetic agitator stirring. The samples were stirred for 24 hours at room temperature.

Concerning plastics, S1 to S12 samples were used. With regard to surfactants, the three surfactants were used, with three different concentrations for each surfactant, which were separately used to make drops on all the samples.

Characterization of samples

We measured the character of samples, their density, humidity and surface micrograph, so that we could analyze the relation between surface properties and the results in experiments.

Density

The objective of the following tests is to make sure that materials' density will not influence the result in flotation experiments. Density is an important criterion in the experiment, as the experiment is conducted in aqueous conditions. The density of these plastic materials should be more than the density of water, otherwise, all the particles will float upwards and the separation of selected plastics will not be achieved. For this purpose, the density of samples in the experiments was tested.

The mass of each sample was measured in air and deionized water with an analytical balance, the density equals to

𝜌 = 𝑚 𝑎𝑖𝑟 𝑚 𝑎𝑖𝑟 -𝑚 𝑤𝑎𝑡𝑒𝑟 × 𝜌 𝑤𝑎𝑡𝑒𝑟𝑇°measure 𝐸𝑞1
Where mair and mwater are the mass of the sample in the air or in the water, and 𝜌 𝑤𝑎𝑡𝑒𝑟𝑇°measure is the density of water at the measurement temperature. The ambient temperature was 20 ℃ so 𝜌 𝑤𝑎𝑡𝑒𝑟𝑇°measure was 998.2 kg/m 3 .

Humidity

As the plastics are exposed to ambient air, they are not totally dry, which means they contain a certain humidity. This may influence the result of the wettability test, so we also measure the humidity of different types of plastic.

The samples were dried and continuously weighed at time =1, 2, 3, 4, 5, 6, 7, 9, 12, 17, 24, 48, 72 hours, until there was no further change in the weight of samples. Two samples were selected for each type of plastic, the results are listed below. Materials ABS ABS RF HIPS HIPS RF PP PP RF Humidity 0.327% 0.305% 0.026% 0.041% 0.001% 0.040%

Fourier-transform infrared spectroscopy (FTIR)

An FTIR was conducted to investigate whether the changes of microscopic molecular structures occur on plastic surface after oxidation. FTIR spectra of ABS before and after oxidation are shown in figure 3-11. Spectrum of untreated ABS sample shows typical pics at 2240 cm -1 (acrylonitrile); 1600 cm -1 , 1490 cm -1 , 1454 cm -1 (the stretching in aromatic rings); -C-H stretch at 3030 cm -1 (aromatic rings), 2850 cm -1 and 2920 cm -1 (ethylene); -C-H bending vibrations at 700 cm -1 , 760 cm -1 (aromatic rings). Moreover, a apparent pic between 3120 cm -1 and 3730 cm -1 indicates the presence of OH groups, which is ascribed to water molecules in the ABS samples.

Scanning electron microscopy (SEM)

An SEM was employed to observe the plastic surface. To obtain images of the plastic surface, the specimens were placed separately onto a metal holder with carbon tape. The images were captured using a Hitachi S3500N under low magnification.

Conclusion

In this chapter, we proposed the choice of materials that are ABS, HIPS and PP filled with 20% talc as they have similar densities and they are dark colored plastics. Also, they are the most presented in WEEE plastics. Since the traditional sorting methods have difficulties in treating these plastics, a new method is necessary to be studied in order to improve the sorting efficiency, so these plastics are one of our research items. Then, to conduct the flotation experiment, the surfactants are the essential reagents. After made the state of art, we have chosen three surfactants to be operated with. The experimental approach and preparation of samples are described, then the characterizations of samples are carried out by testing their densities, humidity and micrograph by SEM.

Chapter Study of wettability of materials

Introduction and definition of wettability

Wetting is the ability of a liquid to maintain contact with a solid surface, resulting from intermolecular interactions when the two are brought together. It deals with the three phases of materials: gas, liquid, and solid. Wettability is defined from a macroscopic point of view by the spreading of a liquid on the surface of a solid. From a thermodynamic point of view, the wettability is a function of the liquid-solid interfacial tension which is relative to the surface composition of solids and the nature of the liquid.

Surface tension

Surface tension is the elastic tendency of a fluid surface which makes it adopt the form with the least possible surface area. At liquid-air interfaces, surface tension results from the greater attraction of liquid molecules to each other than to the molecules in the air. The net effect is an inward force at its surface that causes the liquid to behave as if its surface were covered with a stretched elastic membrane. Thus, the surface is under tension from the imbalanced forces, which is probably where the term "surface tension" came from[107].

Surface tension is responsible for the shape of liquid droplets. Although easily deformed, droplets of water tend to be pulled into a spherical shape by the imbalance in cohesive forces of the surface layer. It is measured in force per unit length, and its SI unit is newton per meter. Surface tension acts upon its respective interface, and defines the angle at which the liquid contacts the surface. This is known as the contact angle (wetting angle) of the liquid to the solid in the presence of the gas.

Surface thermodynamics

When considering a liquid on a surface, there are three systems: the liquid, the surface and the surrounding atmosphere, which is referred to as the vapor. Equilibrium considerations allow us to calculate the wetting angle from the surface tensions, the relation between the various surface tensions and the contact angle was given by Young [START_REF] Young | No Title," An essay Cohes. fluids[END_REF] in Eq. 3

𝛾 𝑆𝑉 = 𝛾 𝑆𝐿 + 𝛾 𝐿𝑉 cos 𝜃 𝐸𝑞3 Here S, V and L refer to the substrate surface, the vapor and the liquid respectively. γ is the force, which is the interface tension between each of the three phases (S/L/G), θ is the contact angle as shown in Figure 4-1. Young's equation in the above form describes an equilibrium situation when the surface tension forces balance each other. For a given set of surfaces, the corresponding contact angle θ can be obtained from the surface tensions involved. If, for instance γSV = γSL + γLV, then θ = 0 and equilibrium corresponds to the situation when the liquid is spread across the surface of the substrate. This situation is referred to as wetting. The other two phases that arise are the non-wetting phase and the partial wetting phase. As shown in Figure 4-2, a contact angle less than 90° (low contact angle) usually indicates that wetting of the surface is very favorable, and the fluid (in blue) will spread over a large area of the surface, indicating a total wetting or a partial wetting. Contact angles greater than 90° (high contact angle) generally means that wetting of the surface is unfavorable, so the fluid will minimize contact with the surface and form a compact liquid droplet, indicating a partial wetting or no wetting. Since during division two individual parting surfaces 2A are produced, Wii can be calculated from the surface tension γ (which is defined as the work per surface difference) according to the following equation:

𝑊 𝑖𝑗 = 𝛾 𝑖 + 𝛾 𝑗 -𝛾 𝑖𝑗 𝐸𝑞4
Where 𝛾 𝑖𝑗 represents the interfacial tension between the two phases.

For the case of a liquid and a solid, according to DUPRE's theory and Young's equation, (DUPRE)𝑊 𝐴 = 𝛾 𝑙 + 𝛾 𝑠 -𝛾 𝑙𝑠 𝐸𝑞5

(YOUNG)𝛾 𝑠 -𝛾 𝑙𝑠 = 𝛾 𝑙 cos 𝜃 𝐸𝑞6

𝑊 𝐴 = 𝛾 𝑙 + 𝛾 𝑙 cos 𝜃 = 𝛾 𝑙 (1 + cos 𝜃) 𝐸𝑞7

Oss and Good (Acid-Base)

In the theory of OSS and GOOD [START_REF] Van Oss | Surface Tension and the Solubility of Polymers and Biopolymers: The Role of Polar and Apolar Interfacial Free Energies[END_REF], this model is also based on the geometric mean as well. However, according to LEWIS, with the help of the Acid-Base-Model the polar part can now be described. The polar part is divided into an acid part 𝛾 + and a base part 𝛾 -; this leads to the following equation [START_REF] Spelt | The equation of state approach to interfacial tensions[END_REF]:

𝛾 𝑠𝑙 = 𝛾 𝑠 + 𝛾 𝑙 -2 (√𝛾 𝑠 𝐷 • 𝛾 𝑙 𝐷 + √𝛾 𝑠 + • 𝛾 𝑙 -+ √𝛾 𝑠 -• 𝛾 𝑙 + ) 𝐸𝑞8

Owens, Wendt, Rabel, Kaelble

For polar liquids OWENS and WENDT [START_REF] Owens | Estimation of the surface free energy of polymers[END_REF] assumed that there was a polar part of the surface tension. For the interfacial tension between two phases with polar parts the following equation is obtained as an extension of Equation before:

𝛾 12 = 𝛾 1 + 𝛾 2 -2 (√𝛾 1 𝐷 • 𝛾 2 𝐷 + √𝛾 1 𝑃 • 𝛾 2 𝑃 ) 𝐸𝑞9

Equation of State

The Equation of State was obtained during the search for a method of determining the surface energy of a solid from a single contact angle measurement by using a liquid with known surface tension.

Starting with the equation of Young 𝛾 𝑠 = 𝛾 𝑠𝑙 + 𝛾 𝑙 • 𝑐𝑜𝑠𝜃 𝐸q10 It can be seen that a second equation is required which also describes the surface energy of the solid as a function of the interfacial tension solid/liquid and the surface tension of the liquid:

𝛾 𝑠 = 𝑓 (𝛾 𝑠𝑙 , 𝛾 𝑙 ) 𝐸𝑞11 From thermodynamic considerations it was first demonstrated that such an equation valid for all systems must exist. By using an enormous volume of contact angle data, the required equation of state was determined empirically:

𝛾 𝑠𝑙 = 𝛾 𝑙 + 𝛾 𝑠 -2√𝛾 𝑙 • 𝛾 𝑠 • 𝑒 -𝛽(𝛾 𝑙 -𝛾 𝑠 ) 2 𝐸𝑞12
If the equation of state is inserted into Young's equation, then a new equation is obtained which allows the calculation of the surface tension of the solid 𝛾 𝑙 from a single contact angle if the surface tension 𝛾 𝑠 is known:

𝑐𝑜𝑠𝜃 = -1 + 2 √ 𝛾 𝑠 𝛾 𝑙 • 𝑒 -𝛽(𝛾 𝑙 -𝛾 𝑠 ) 2 𝐸𝑞13
In the calculation of the surface energy with the help of the Equation of State the type of interactions which lead to the formation of the interfacial tensions (polar or disperse interactions) are not considered.

The FOWKES method

By using the FOWKES method [START_REF] Fowkes | Attractive forces at interfaces[END_REF] the polar and disperse parts of the surface free energy of a solid can be obtained. Strictly speaking this method is based on a combination of the knowledge of FOWKES, on the one hand, and that of OWENS and WENDT, on the other, as FOWKES initially determined only the disperse part and the latter determined both the components of the surface energy.

Step 1: Determining the disperse part In this first step the disperse part of the surface energy of the solid is calculated by making contact angle measurements with at least one purely dispersed liquid.

By combination of the surface tension equation of FOWKES for the disperse part of the interactions

𝛾 𝑠𝑙 = 𝛾 𝑠 + 𝛾 𝑙 -2 √𝛾 𝑠 𝐷 • 𝛾 𝑙 𝐷 𝐸𝑞14
With YOUNG's equation, the following equation for the contact angle is obtained after transposition:

𝑐𝑜𝑠𝜃 = 2√𝛾 𝑠 𝐷 • 1 √𝛾 𝑙 𝐷 -1 𝐸𝑞15
And, based upon the general equation for a straight line, 𝑦 = 𝑚𝑥 + 𝑏 𝐸𝑞16

𝑐𝑜𝑠𝜃 is then plotted against the term 1/√𝛾 𝑙 𝐷 and 2√𝛾 𝑠 𝐷 can be determined from the slope m.

It is possible to determine the disperse part from a single contact angle. However, a linear regression with several purely disperse liquids is more accurate.

Step 2: Determining the polar part For the 2nd step, the calculation of the polar part, equation 14 is extended by the polar part:

𝛾 𝑠𝑙 = 𝛾 𝑠 + 𝛾 𝑙 -2 (√𝛾 𝑠 𝐷 • 𝛾 𝑙 𝐷 + √𝛾 𝑠 𝑃 • 𝛾 𝑙 𝑃 ) 𝐸𝑞17
It is also assumed that the work of adhesion is obtained by adding together the polar and disperse parts: 𝑊 𝑠𝑙 = 𝑊 𝑠𝑙 𝐷 + 𝑊 𝑠𝑙 𝑃 𝐸𝑞18 and then as a third step YOUNG's equation:

𝛾 𝑠 = 𝛾 𝑠𝑙 + 𝛾 𝑙 • 𝑐𝑜𝑠𝜃 𝐸𝑞19 is added to the equation of DUPRE:

𝑊 𝑠𝑙 = 𝛾 𝑠 + 𝛾 𝑙 -𝛾 𝑠𝑙 𝐸𝑞20 to obtain the following relationship for the work of adhesion:

𝑊 𝑠𝑙 = 𝛾 𝑙 (𝑐𝑜𝑠𝜃 + 1) 𝐸𝑞21 Now all the components required for the calculation of the polar part of the surface energy have been assembled. A combination of previous equations produces:

𝑊 𝑠𝑙 𝑃 = 𝛾 𝑙 (𝑐𝑜𝑠𝜃 + 1) -2√𝛾 𝑠 𝐷 • 𝛾 𝑙 𝐷 𝐸𝑞22
Based upon this relationship the contact angles of liquids with known polar and disperse parts are measured and 𝑊 𝑠𝑙 𝑃 calculated for each liquid.

The polar part of the work of adhesion is defined by the geometric mean of the polar parts of the particular surface tensions:

𝑊 𝑠𝑙 𝑃 = 2√𝛾 𝑙 𝑃 • √𝛾 𝑠 𝑃 𝐸𝑞23
then, by plotting 𝑊 𝑠𝑙 𝑃 against 2√𝛾 𝑙 𝑃 and following this with a linear regression, the polar part of the surface energy of the solid can be determined from the slope.

The method according to Owens, Wendt, Rabel and Kaelble

According to OWENS, WENDT, RABEL [START_REF] Rabel | Einige Aspekte der Benetzungstheorie und ihre Anwendung auf die Untersuchung und Veränderung der Oberflächeneigenschaften von Polymeren[END_REF] and KAELBLE [START_REF] Kaelble | Dispersion-Polar Surface Tension Properties of Organic Solids[END_REF] the surface tension of each phase can be split up into a polar and a disperse part:

𝛾 𝑙 = 𝛾 𝑙 𝑃 + 𝛾 𝑙 𝐷 Eq24 𝛾 𝑠 = 𝛾 𝑠 𝑃 + 𝛾 𝑠 𝐷 𝐸𝑞25
The FOWKES method for calculating the surface energy has already been developed from this relationship. In contrast to the FOWKES method, in the OWENS, WENDT, RABEL and KAELBLE method the calculation of the surface energy of the solid takes place in a single step. OWENS and WENDT used the equation for interfacial tension

𝛾 𝑠𝑙 = 𝛾 𝑠 + 𝛾 𝑙 -2 (√𝛾 𝑠 𝐷 • 𝛾 𝑙 𝐷 + √𝛾 𝑠 𝑃 • 𝛾 𝑙 𝑃 ) 𝐸𝑞26
as their basis and combined it with the YOUNG equation 𝛾 𝑠 = 𝛾 𝑠𝑙 + 𝛾 𝑙 • 𝑐𝑜𝑠𝜃 Eq27 The two authors solved the equation system by using the contact angles of two liquids with known disperse and polar parts of the surface tension. KAELBLE [START_REF] Kaelble | Dispersion-Polar Surface Tension Properties of Organic Solids[END_REF] solved the equation for combinations of two liquids and calculated the mean values of the resulting values for the surface energy.

RABEL made it possible to calculate the polar and disperse parts of the surface energy with the aid of a single linear regression from the contact angle data of various liquids. He adapted the resulting equation by transposition to the general equation for a straight line 𝑦 = 𝑚𝑥 + 𝑏 Eq28 The transposed equation is shown below:

(1 + 𝑐𝑜𝑠𝜃) • 𝛾 𝑙 2√𝛾 𝑙 𝐷 = √𝛾 𝑠 𝑃 √ 𝛾 𝑙 𝑃 𝛾 𝑙 𝐷 + √𝛾 𝑠 𝐷 Eq29
In a linear regression of the plot of y against x is obtained from the square of the slope of the curve m and from the square of the ordinate intercept b.

Laboratory measurement of wettability

There are several methods for determining wettability of a solid with various fluids. In spite of the importance attributed to wettability, no standardized technique exists that completely and adequately characterizes the phenomenon, while the most common used method is by measuring the contact angle. It is also used in our study since it is more direct, easier and suitable compared with other methods.

Contact angle measurement

Many methods of contact-angle measurement have been developed, but the two most common used are the/an optical method and a forces tensiometry method. Both techniques are described below, with comments on the choice of either technique for particular applications.

Optical tensiometry

Both static and dynamic contact angles can be measured by goniometer. The static contact angle is the contact angle when the contact area between liquid and solid is not changed from the outside during the measurement, in contrast to the dynamic contact angle which is produced in the course of wetting (advancing angle) or de-wetting (receding angle) [START_REF] Thomsen | Practical Contact Angle Measurement (5): Custom-made models: from contact andle to surface free energy[END_REF] . In practice, a droplet is placed on the solid surface and the image of the drop is recorded. The static contact angle is then defined by fitting a Young-Laplace equation around the droplet, although other fitting methods such as a circle and a polynomial can also be used.

Dynamic contact angles can be measured using two different approaches: changing the volume of the droplet or by using a tilting cradle. Figure 4-3 (a) shows the principle of the volume changing method. In short, a small droplet is first formed and placed on the surface. The needle is then brought close to the surface and the volume of the droplet is gradually increased, while recording at the same time. This will give the advancing contact angle. The receding angle is measured the same way but this time, the volume of the droplet is gradually decreased. In Figure 4-3 (b), the principle of the tilting cradle method is shown. The droplet is placed on the substrate, which is then gradually tilted. The advancing angle is measured at the front of the droplet just before the droplet starts to move. The receding contact angle is measured at the back of the droplet, at same time point. The optical method is the best choice when liquid-solid interactions and/or solid properties (such as surface free energy) are measured on samples that are not homogeneous nor regular in size and shape. The main benefits are obvious, such as the small liquid volume demanded only some microliters, contact angle mapping over the surface enables heterogeneity and cleanliness tests. It is not necessary for both sides of the sample to be similar, so it is possible to apply a coating or other surface modification characterizations, etc. [START_REF] Spelt | The equation of state approach to interfacial tensions[END_REF]

Force tensiometry

A force tensiometer measures the weight mass affecting to the balance when a sample of solid is brought in contact with a test liquid. This method is also called the Wilhelmy plate method [START_REF] Karim | Effect of viscous force on dynamic contact angle measurement using Wilhelmy plate method[END_REF]. When a vertically suspended plate touches a liquid surface or interface, then a force F, which correlates with the surface tension or interfacial tension on this plate, the contact angle can then be calculated by using the equation Eq30 when surface tension of the liquid (γL) and the wetted length of the sample (L) are known. The force acting on a vertically immersed plate is measured using the following equation: In figure 4-5, a complete contact angle measurement cycle is presented. As can be seen, with force tensiometer the measured contact angle is always dynamic contact angle since the sample is moving against the liquid. When the sample is immerged to the liquid the advancing contact angle is recorded and when the sample is emerging the receding contact angle is measured. The graph of force/wetted length versus depth of immersion appears as follows:

F = 𝛾 𝐿 • 𝐿 cos 𝜃 𝐸𝑞30
1. The sample is above the liquid and the force/length is zero.

2.

The sample hits the surface. For the sample as shown, with a contact angle < 90°, the liquid rises up causing a positive force.

3.

The sample is immersed, buoyant force increases causing a decrease in the force on the balance. Forces are measured for advancing angle. 4.

After having reached the desired depth the sample is pulled out of the liquid. Forces are measured for receding angle.

2. Fill the syringe with surfactant solvent and place it on the support above the operating platform and place the sample on the platform support. 3. Adjust the light source, normally a weak separating line can be seen between an upper brighter area and a lower darker area. Optimal brightness is usually achieved when the dark area is just below the baseline. Then adjust the camera in order to clearly see the needle tip and the sample support platform 4. Adjust the volume of drops (5μL) and speed of execution, a series of tests were formerly conducted to adjust the best speed, the drops is not stable if the forming of drops is too fast, higher speeds are only suitable for emptying or filling the syringe. 5. click the button to automatically form the drops and capture the drop's image Once the drop is deposited on the plastic, the acquisition of the measurement is done as follows: the image is captured by the camera and the baseline of drop should be defined. (The baseline of a drop image is the boundary between the solid surface and the drop.) As the absolute height of the surface is unknown, the baseline must be determined in the evaluation of the drop image. For the exact calculation of baseline, this means a high-quality drop image must first be available.

Two angles of the drop, on the left and on the right, were calculated by the software. The value collected for each drop's contact angle is the average of these two measurements. 5 to 8 drops were repeated for each sample.

Experiment of contact angle measurement and results

The objective of the contact angle experiment is to evaluate the wettability of each plastic, with or without some modification of the surface, to evaluate the possibility of modifying the wettability of materials with different surfactant agents, and to provide the optimized conditions for trying to separate these three plastics in subsequent flotation experiments.

Firstly, contact angles with deionized water on the samples were tested, and the results are listed below: The technique described here, contact angle, is a technology for measuring the contact angle and thus calculating the free surface energy of solids from the corresponding equations. The instrumentation makes it possible to measure the static and dynamic surface and interfacial tension.

The described techniques can be easily modified to control several variables that influence the surface tension and the contact angle. The technique requires an analysis, and image processing is done with various programs, the experimental drop data profile corresponds to the Young-Laplace equation which is solved by numerical methods.

The fundamental plastics used in contact angle experiments are ABS, HIPS and talc filled PP, the surfactants are NaCMC, MC, and PVA as mentioned in last chapter. For the purpose of achieving the experiment's objective, several parameters are varied to observe their influence on contact angle.

Protocol of surface tension experiments

Due to the immobility of molecules in a solid phase, solid surface tensions are difficult to measure directly. Hence several indirect approaches, both experimental and theoretical, have been used. They include contact angle measurements with different liquids, direct force measurements, solidification front techniques, film flotation, and the Lifshitz theory of van der Waals forces. Among these methods, the contact angle approach is the most broadly applicable one [START_REF] Tavana | Recent progress in the determination of solid surface tensions from contact angles[END_REF].

Formamide, glycerol, ethylene glycol, diiodomethane and α-bromonaphthalene are frequently used for calculations of components and parameters of solid surface tension using the van Oss et al. theory, However, as reported in the literature other liquids are also used as model liquids for determination of solid surface tension by contact angle measurements [START_REF] Zdziennicka | Components and parameters of liquids and some polymers surface tension at different temperature[END_REF]. It was concluded that the components and parameters of model liquids surface tension used for determination of solid surface properties should be obtained from the contact angle measurements on model solids [121][41]. It proved that PTFE is an ideal solid as the reference for determination of the Lifshitz-van der Waals and acid-base components of liquid surface tension but PMMA for determination of the electron-acceptor and electron-donor parameters of acid-base component. Taking into account the contact angle for the homologous series of n-alkanes on the surface of PTFE its surface tension was found earlier to be equal to 20.24 mN/m [START_REF] Jaṅczuk | Relationship between wetting of Teflon by cetyltrimethylammonium bromide solution and adsorption[END_REF]. Next, on the basis of the contact angle of water, ethylene glycol and diiodomethane on the PTFE surface, the Lifshitz-van der Waals component of these liquids surface tension was determined.

For the solids, whose surface tension results not only from dispersion but also polar intermolecular interactions, the contact angle at least for two liquids should be measured on given polar solids.

In order to avoid a large error in calculations of solid surface tension components, the applied liquids for contact angle measurements should have significantly different components of the surface tension. This condition is satisfied by the pair of liquids [START_REF] Zdziennicka | Some remarks on the solid surface tension determination from contact angle measurements[END_REF].

The contact angles of the three substances on each sample were repeated 5 to 8 times to collect the average value for calculation. For example, as the table listed below, CA is measured contact angle, the neat ABS is defined as sample 1, ABS with flame retardant is sample 2, neat ABS with thermal treatment is sample 3, ABS with flame retardant treated by thermal aging is sample 4.

The three liquids used for surface tension determination are deionized water, diiodomethane and ethylene glycol, defined as a, b and c. In this case, CA1a is the contact angle (average value) of a deionized water drop on the neat ABS surface. With the group of contact angles of the three reference liquids on neat ABS surface (CA1a, CA1b and CA1c), and their surface tension (polar and dispersive) tested, the surface tension of neat ABS is calculated by inserting these values into the YOUNG, DUPRE, OWENS WENDT equation.

Results from contact angle measurement

Effect of addition of bromine flame retardant TBBPA

The main objective of this experimental study is to observe the effect of the addition of TBBPA to ABS. The results are expressed in the following figures with bar graphs. The presentation of the bar graph is as illustrated before. The values of TBBPA filled surfaces are generally slightly higher than those of neat ABS surface, the same as in figure. 4-7 where the values are for NaCMC. A general conclusion for neat ABS surface and ABS filled with TBBPA is that the addition of TBBPA has a slight influence on materials, reflected in a rise in the hydrophobicity that influenced contact angles.

Effect on ABS

Effect on HIPS

Following the previous result, the measured values of contact angle for NaCMC on a neat HIPS surface and a HIPS filled with 15% TBBPA surface were evaluated, the result is shown in figure 456789. The results from MC on neat HIPS surface and HIPS filled with 15% TBBPA surface, and the results from PVA on neat HIPS surface and HIPS filled with 15% TBBPA surface are listed in figure 4-10 below, using MC as surfactant, the contact angle on HIPS filled with TBBPA surface is smaller than that on a neat HIPS surface, the same conclusion as for NaCMC. In the case of PVA as surfactant, at a concentration of 100 mg/L and 200 mg/L, the contact angle on the HIPS filled with TBBPA surface is slightly higher than that of the neat HIPS surface. The bar graph resembles the previous figures, bar height represents the average value of contact angle. At 50 mg/L NaCMC, the contact angle on a neat PP surface is 99.2° and on a TBBPA filled PP it is 88.3°. When the concentration is 100 mg/L, these values increase slightly to 100.5° and 89.2° respectively. At a concentration of 200 mg/L, a difference in contact angle values appeared: contact angle on the neat PP surface is 99.9°and contact angle on the TBBPA filled PP surface is 95.6°. It can be concluded from the three comparisons that the values of contact angle for NaCMC on neat PP surface is always higher than the angle on PP with 15% TBBPA surface, independent of NaCMC concentration.

To compare the effect of the addition of TBBPA on the material's surface in wettability tests, the measured contact angle values for MC on a neat PP surface and a PP filled with 15% TBBPA surface, and measured values of contact angle for PVA on neat PP surface and PP with 15% TBBPA surface are also studied. A comparison of the results is shown in figure 4-12 below. In both cases, with MC and PVA as surfactants, the contact angle on PP filled with TBBPA surface is smaller than that on a neat PP surface, the same conclusion as before.

Effect of thermal aging of materials

The objective of this section is to observe the effect of aging on materials. We have previously explained the matrix of samples, and, in this section, samples S1 to S4 are used to demonstrate the aging effect on samples based on ABS. Samples without thermal treatment are in blue bars, and samples treated by thermal aging are in red bars. From these graphs, it can be deduced that the effect of thermal aging is relatively more obvious than the effect of bromine flame retardant TBBPA. For example, comparing the contact angle value for PVA on a virgin ABS surface and an aged ABS surface, at 50 mg/L of PVA, contact angle on an untreated surface is 79.7° and on the thermal treated surface it is 73.1°. At 100 mg/L of PVA, the contact angles are 83.2° and 69.6° respectively, and at 200 mg/L of PVA, they are 76.1° and 64.9°. The contact angle values on aged ABS are smaller than contact angle values on virgin ABS surface.

The general conclusion is that thermal aging has an effect on material surfaces, samples treated by thermal aging have smaller contact angles, indicating that they are more hydrophilic.

To investigate the effect of thermal aging on other materials, samples S5-S8 correspond to samples based on HIPS: neat & virgin HIPS; HIPS filled with bromine flame retardant; aged HIPS and aged HIPS filled with bromine flame retardant. These are tested with different surfactants on their surface. For samples based on HIPS, the effect of aging on samples' surface is more apparent, for all the samples, surfaces treated by thermal aging have smaller contact angles, indicating that they are more hydrophilic.

PP samples also show the same tendency figure 4-16: The effect of aging on PP samples' surface is also apparent, surfaces treated by thermal aging have smaller contact angles.

Surface wettability of plastics is largely determined by the surface morphology and the surface functional groups. During thermal oxidation, the augmentation of surface roughness and the introduction of hydrophilic oxygen-containing groups such as C-O and O-C=O groups on plastic surface are expected to increase the surface hydrophilicity.

These observations lead us to the conclusion that, it can be concluded that aging has an effect on sample surfaces, making them more hydrophilic, which is the reason smaller contact angles are observed. It shows that as talc content in PP plastics increased, contact angle decreased. This demonstrates that talc content has an effect on PP plastics surfaces, making them more hydrophilic.

Effect of talc content in PP

Taking samples with MC surfactant as an example: at 50 mg/L, the contact angle on neat PP surface is 97.9°; on 10% talc filled surface is 92.6°, and on 20% talc filled surface is 86.5°. It shows that for these three sample, the value of contact angle on neat PP is higher than PP talc 10, and, for both these samples, it is higher than PP talc 20 surface. In conclusion, talc has an effect on PP surfaces, a higher content of talc makes the surface more hydrophilic.

Comparing the results of contact angles on the three polymers' surface, the polymers' contact angles are often similar. However, when PVA is served as surfactant with the concentration at 50 mg/L, it seems to create the largest difference of contact angle values among the polymers, this will be further observed in the flotation experiment.

Results from surface tension experiments

The calculation of surface tension of materials was carried out using an Excel function, according to a combination of Young, Dupre, Oss and Owens theory. The principle is presented in section 4.2.6 that with equations combined and adapted, the resulting equation by transposition to the general equation for a straight line. The transposed equation is shown below:

(1 + 𝑐𝑜𝑠𝜃) • 𝛾 𝑙 2√𝛾 𝑙 𝐷 = √𝛾 𝑠 𝑃 √ 𝛾 𝑙 𝑃 𝛾 𝑙 𝐷 + √𝛾 𝑠 𝐷 𝐸𝑞31
In a linear regression of the plot of y against x is obtained from the square of the slope of the curve m and from the square of the ordinate intercept b, where The result shows that addition of talc tends to make PP surface tension bigger, and the addition of bromine flame retardant also leads the plastics surfaces' tension to be bigger.

(1+ 𝑐𝑜𝑠𝜃) • 𝛾 𝑙

Conclusion

In this chapter, the contact angles are tested. The objective of the contact angle experiment is to evaluate the wettability of each plastic, with or without some modification of the surface, to evaluate the possibility of modifying the wettability of materials with different surfactant agents, and to provide the optimized conditions for trying to separate these three plastics in subsequent flotation experiments. From the result we found that thermal aging has an effect on material surfaces, samples treated by thermal aging have smaller contact angles, indicating that they are more hydrophilic. Besides, the addition of bromine flame retardant and talc will also influence the hydrophobicity of material, making them more hydrophilic.

Finally, PVA is proposed to serve as surfactant with the concentration at 50 mg/L, because it seems to create the largest difference of contact angle values among the polymers, this will be further observed in the flotation experiment.

Chapter Study of flotation

Flotation is a widely-used technique for separation and recuperation in the mineral industry for example 80% of world copper production uses froth flotation [START_REF] Fraunholcz | Separation of waste plastics by froth flotation --a review , part I[END_REF]. This is a selective process for separating minerals from precipitate by using surfactants and wetting agents. The flotation process is used for the separation of a large range of sulfides, carbonates and oxides prior to further refinement. Phosphate and coal are also processed by flotation technology.

In the froth flotation of mineral processing, the initial procedure was used to increase the surface area of the ore for subsequent processing and to break the rocks into the desired mineral and gangue (which then has to be separated from the mineral). In this stage, the ore is ground into a fine powder. The desired mineral is rendered hydrophobic by the addition of a surfactant or collector chemical, the particular chemical depends on the mineral is being refined. For example, pine oil is used as surfactant to extract copper.

In this chapter, a flotation experiment on plastic particles is discussed.

Materials and methods for flotation experiment

For the purpose of more closely approaching industrial applications, the water used in the flotation tank is tap water. Acetic acid was used to regulate the pH of the medium.

The surfactant agents used are Sodium Carboxyl Methyl Cellulose (NaCMC), Methyl Cellulose (MC) and Polyvinyl Alcohol (PVA), based on the literature and former research on flotation. In addition, terpinol was used as the frother.

The surfactant agents are powders that have to be dissolved in water. The dissolution process of these surfactants is relatively slow, for the purpose of convenience during flotation experiments, they were firstly prepared at a higher concentration with the help of a magnetic agitator, then these solutions are diluted in the flotation medium at the desired concentrations (25/50/75/100 mgL -1 )

Flotation Experiment methodology

The flotation tests were carried out in a self-designed glass flotation column (Figure 5-1) with a height of 500mm and a diameter of 150mm. This column is mechanically agitated by a rotating impeller located at the bottom of the cell at 900 rpm, its motor was above the column. The objective of agitation is to enhance the selective affinity of air bubbles for plastic particles, it allows air bubbles and particles to aggregate and creates a homogenous condition of surfactant agents. The effect of turbulence is especially important in the flotation of plastics due to the low density of plastics and the weak forces between particles and air bubbles. The volume of flotation medium is 4L. Plastic particles were stirred with the surfactant agents in the column for 15 mins. Then compressed air was introduced from the bottom of the column, and air bubbles were produced due to a porous board at bottom of the column just above the air intake. The airflow rate was fixed at 1.3L min -1 after airflow rate tests which provided a stable condition for flotation. The flotation test was conducted for 10 mins. At the end of the flotation test, particles which had floated up to the interface of water and air were collected, rinsed with tap water, dried in atmosphere conditions, and separately weighed by type, as each color represents one type of plastics. The flotation rate of each plastic in the floated product was calculated based on mass balance. The temperature was not artificially changed, it was room temperature at 22℃. The experiments are divided into two groups, the objective is to study the influence of two factors, one is aging, the other is the efficiency of different surfactants.

Results and discussion

The results of the flotation experiment are expressed in terms of recovery, by percentages, in the float products. The effect of flotation can be visually observed throughout the recovery, the bigger the difference in the plastics' floating rates, the better the separation achieved. The mass of each type of plastic floated was weighed after manually sorting the mixture, the float recovery for each plastic were calculated by equation below.

Recovery percentage = 𝑚 𝑓

𝑖 𝑚 𝑡 × 100% 𝐸𝑞33

where 𝑚 𝑓 𝑖 is the mass of the plastic i (ABS, HIPS or talc filled PP) in the floating particles and mt is the original selected sample mass of plastic i.

Effect of aging of plastics

The aim of choosing aging effect as a research point is that, when equipment has arrived at its end of life, it has suffered thermal, moisture or ultraviolet oxidations, which lead to different surface conditions compare to the original ones. We would like to observe if these modifications have an effect on flotation separation.

End of life plastics are different from virgin plastics due to surface inhomogeneity of waste plastic, which is enhanced by the presence of additives and the history of plastic utilization. The main additive in WEEE plastics is flame retardant, we have analyzed their composition and conducted primary experiments on plastics filled with flame retardant and same type of plastic without flame retardant. Our results showed that addition of flame retardant doesn't have a significant effect, the potential performance difference is mainly as a result of utilization of plastic.

The first factor studied is aging during utilization. The effect of aging was studied for two types of plastics: ABS and HIPS. The comparisons of recovery rate of virgin ABS and end of life ABS, virgin HIPS and end of life HIPS are listed below. Each plastic was tested with the three surfactants at a variety of concentrations. It shows that with tap water, before adding the surfactants, the recovery of virgin ABS and virgin HIPS plastics is more than 90%, in fact the recovery of HIPS is close to 100%, and Eol (End of Life) plastics have lower recovery. When adding NaCMC at 25mg/L, the recovery of all the tested plastics decreased but EoL ABS is least affected. The reduction of recovery is due to the depression by surfactant, it means at concentration of 25mg/L more plastics were depressed than zero concentration. However, when concentration continues to grow, from results at 50, 75 and 100 mg/L the recovery remains at same level, this demonstrates that the wettability of both plastics is unchanged by higher concentrations.

When using NaCMC as surfactant agent,

When using MC as surfactant agent,

0.00% Data from MC experiments shows that the depression effect continuously increased with growth of MC concentration. When adding more MC as surfactant, less plastic recovery was obtained and this can be applied to both the types of plastic. Less recovery of HIPS plastics is obtained when compared with ABS plastics at same surfactant concentration. This result is similar to the former experiment with NaCMC. In addition, it can be seen that End of life plastics always float less than virgin plastics, this could be explained by modification of polymer's structure after aging.

Aging damages polymers, it causes chemical bonds to break and the C-O or O-H links are formed with oxygen, these are typical polar covalent bonds. Therefore, polymers after oxidation become more hydrophilic than before, with the influence of surfactant agents, the hydrophobic plastic surfaces have a stronger attachment to air bubbles than the hydrophilic plastic surfaces. The mechanism relations of wettability and contact angle performance/flotation performance will be further discussed in chapter 6. For ABS plastics, the result fluctuation is not very obvious, they maintain at same level, not influenced by PVA concentration, virgin ABS and EoL ABS follow the same trend, at the same time, EoL ABS is more readily depressed by surfactant than virgin ABS at each concentration.

For HIPS plastics, figure 5-8 shows the recovery of virgin particles and EoL particles in float product as the concentration of PVA varies. At 25 mg/L, about 30% to 40% of plastics were depressed, while at 50 mg/L only 8% were depressed. When concentration arrived at 75 mg/L, they were roughly similar, and depression effect was again about 55%. This can be explained by multi coating layers on particles. In the paper of Dodbiba [START_REF] Dodbiba | Combination of sinkfloat separation and f lotation technique for purification of shredded PET-bottle from PE or PP flakes[END_REF], it is assumed that the PVA reagent has the ability to form a long chain of ''-OH'' functional group. Firstly, with approximately 25 mg/L of PVA, the HIPS plastics' floatability decreased as they became less hydrophobic. Following this, the froth layer in the flotation cell gradually stabilized while the concentration of PVA was increased (up to 75mg/L). Therefore, recovery of the hydrophobic HIPS plastics was high, due to the fact that they could be captured by the froth layer. Increasing the concentration of PVA to 100mg/L decreased the hydrophobicity of the plastics, perhaps due to the creation of long chains of hydrogen functional groups.

In general, in these experiments three surfactants were used separately to observe their depression effect on virgin/EoL plastics. The results revealed that EoL products are more readily depressed by all surfactants used, as EoL products possess polar covalent bonds such as carbon-oxygen single or double bonds, and hydrogen bonds. Therefore, after oxidation polymers become more hydrophilic than before, with the influence of surfactant agents, the hydrophobic plastic surfaces have a stronger attachment to air bubbles than the hydrophilic plastic surfaces. Thus, the floatability of EoL products is lower than virgin products.

After effect of plastics aging had been studied, the EoL plastics were used to observe the effect of surfactants. Since we focus on WEEE plastics, the sorting only treats EoL plastics, so in the following study only Eol plastics are used.

Effect of surfactant agents

In this section, ABS HIPS and 20% talc filled PP waste plastics were selected and their ratio in the sample is 1:1:1. Separation of mixed waste plastics based on polymer type is not obtained when no wetting agent is added, as the three plastics were known to be naturally floatable (hydrophobic). Therefore, it was necessary to use an appropriate surfactant agent to achieve selective separation. It shows that with tap water, before adding the surfactants, the recovery of ABS and HIPS plastics is between 80% and 90%, the recovery of PP is close to 100%. As the concentration of NaCMC increased to 25mg/L, recovery of PP and HIPS decreased while ABS remained almost unaffected. The reduction of recovery is due to the depression by the surfactant, it means that at concentrations of 25mg/L, more plastics were depressed than concentration of 0. However, when concentration increased to 50 mg/L, recovery of ABS and HIPS increased to 95% and 96.4%, indicating more surfactant molecular adhere to plastics surface, while the recovery of PP stayed roughly the same. With further addition of NaCMC, recovery of all plastics remains at the same level, indicating that contact between plastic samples and NaCMC reached a stable state.

Effect of NaCMC concentration

The flotation experiments with NaCMC did not produce the desired high recovery and purity of products. The optimum are at 50, 75 and 100 mg/L that NaCMC could not separate ABS and HIPS but it depressed PP about 20%. MC is one of several cellulose derivatives which are commonly used as an organic depressant or flocculent in mineral flotation. It is obvious that reduced liquid surface tension is not the main reason for the depressive effect of MC on the plastics, since the minimum surface tension of the MC solution is higher than the solid surface tension of the plastics. MC can reduce liquid surface tension to a minimum value of 56.7 mN/m. Therefore, the depressive effect of MC on plastics is ascribed mainly to its adsorption on the plastics surface. MC has numerous polar groups (C-O group and O-H group), the molecules absorbed on the plastic surfaces expose some of their polar groups oriented towards the aqueous phase, hence making the plastic surfaces hydrophilic. For the interaction between MC and plastic surfaces, it is obvious that chemical bonding is very rare because plastics have low surface energies and are nearly chemically inert in this flotation process.

Effect of MC concentration

In addition, electrostatic interaction also can be excluded since MC is a non-ionic substance. Therefore, the adsorption is mainly due to van-der-Waals force interactions.

The performance of flotation experiments with MC were better than previous experiments with MC, at optimum condition, 88% PP floated and 38% HIPS floated but it did not produce the desired high purity of products. Experiments with further improvement were subsequently conducted and the results were valorized in the following sections. Recovery of ABS stayed relatively stable as about 10% was depressed at each concentration. For HIPS, the performance was more complicated: at 25 mg/L, about 40% of HIPS was depressed, while at 50 mg/L only 8% was depressed. This was discussed in section 4.3.1.3. When concentration arrived at 75 mg/L, results were roughly similar, 10% depressed, and at 100mg/L the depression effect was again about 48%.

Effect of PVA concentration

After these experiments with different surfactants, they all produced different levels of depressive effects on plastics. However, the desired high recovery and purity of products were not achieved by individual application. The optimum condition with NaCMC is from 50 mg/L, although NaCMC could not separate ABS and HIPS, it depressed PP about 20%. For MC as surfactant agent, the optimum condition is at 100 mg/L, 88% PP obtained and 38% HIPS floated. While for PVA as surfactant agent, the optimum condition is at 100 mg/L, 30% PP obtained and 90% ABS floated. In last chapter, one of the conclusions is that PVA at 50mg/L was proposed to be an optimum condition for flotation. From the result of flotation, PVA did started to be effective from this concentration but it works better at 100mg/L. Therefore, the choice of surfactant is right but the concentration should be verified in flotation separation. In the next section, regulation of the pH value of solution is further studied. However, PVA was not used because it produces itself a lot of foams in the experiment and due to the dimension of our flotation column, it was difficult to well control the experiment.

Effect of pH

With the former flotation experiments, the mixture was not successfully and completely separated, therefore further experiments were carried out to study the effect of pH of flotation medium. The effect of pH was studied with NaCMC and MC. Nevertheless, MC is not sensible with regulation of pH according to the results of the tests. From former experiments, optimum conditions started at 50mg/L, so the concentration at 50 mg/L is selected in our pH study. Recovery of ABS, HIPS and Talc filled PP were calculated and results are shown in Figure 5-12 below. From the different recovery of each plastic, it is obvious that when pH was changed, the recovery of plastics altered. It seems possible to obtain a separation when the pH is changed when there is only a mixture of talc filled PP and HIPS, or a mixture of talc filled PP and ABS.

In the research of Pascoe [START_REF] Pascoe | The use of selective depressants for the separation of ABS and HIPS by froth flotation[END_REF], it was shown that the response of NaCMC was particularly pH sensitive. The results of flotation experiments with a fixed concentration of NaCMC and variable pH are shown in Figure 5-13 below. It can be seen that selectivity improved in the acidic solution.

Under such conditions, the results in lower pH were separately reproduced in the figure below. NaCMC was found to be an effective depressant of the two plastics without significant reduction in surface tension. The mechanism for depression is therefore adsorption of the organic macromolecule.

At around pH 3 it was found that selective depression of the ABS was possible by using a fixed concentration and conditioning time and PP talc was further depressed to more than 90%. The ineffective depression under alkaline conditions occurs when NaCMC is fully ionized. It is possible that the anionic groups do not readily adsorb onto the negatively charged plastic surface. As conditions become acidic, the NaCMC begins to convert slowly to the acid form (HCMC) accompanied by a reduction in viscosity. Simultaneously the solubility is reduced which may have a bearing on adsorption onto the plastic surface. In all cases the separation of the plastics needs careful control of flotation parameters to achieve a functional separation.

Conclusion

In general, plastic mixtures often show insufficient differences in their interfacial energies [START_REF] Stuckrad | Sorting of waste plastic mixtures by flotation[END_REF].

In such cases, selective modification of the hydrophobic surface is necessary. One method of selective wetting is by chemical conditioning. It is a process in which the adsorption of the reagents on the plastic surfaces leads to a decrease in hydrophobicity of the solid-liquid interface.

In the wetting process, the wettability of different types of plastics is selectively enhanced.

The predominant number of the lateral groups of the polymer chains of the plastics consists of non-polar carbon hydrogens. That is the reason for the mainly physical interactions between the molecules of the plastic surface and the depressant molecules. The interaction force includes the dispersive van-der-Waals force as well as hydrogen bonding. Some polymers contain polar lateral groups with oxygen, nitrogen, chlorine or other atoms. Such lateral groups enable dipole-dipole van-der-Waals interaction as well as Lewis-acid-base interactions with the dipoles of the depressant molecules.

From the results, it is found that chemical bonding between the polymers of the plastic surface and the depressant molecules are very rare, because plastics have low surface energies and are nearly chemically inert under the environment of a flotation process.

Chapter Discussion of results and correlation

This chapter will discuss the results from two former chapters at further detail, to explain the phenomena, then the correlation between contact angle value and flotation results will be discussed statistically using Minitab software.

6.1 Discussion of results from wettability measurement

Influence of different factors in wettability measurement

The variantion of contact angle values is an indication of surface state, the wettability. Surface wettability of plastics is largely determined by the surface morphology and the surface functional groups. Increased surface roughness, and the introduction of hydrophilic oxygen-containing groups such as C-O and O-C=O groups on plastic surface, which are expected to increase the surface hydrophilicity.

In our experiments, the variance was mainly due to two aspects: 1. effect of oxidation (thermal aging) 2. effect of addition of additives, such as bromine flame retardants and of talc These effects will be discussed in the following section.

Effect of oxidation

Thermo-mechanical degradation induced by multiple processing has been proved to cause alterations in the rheological behavior and the mechanical properties of ABS and HIPS [START_REF] Boldizar | Degradation of ABS during repeated processing and accelerated ageing[END_REF][129] [START_REF] Ruth | Studies on morphology and mechanical properties of PP/HIPS blends from postconsumer plastic waste[END_REF]. These changes may be due to chain scission in the PS phase and modifications in the physical structure of the rubber phase [131]. Thermal processing under high mechanical shear in limited oxygen atmosphere may be responsible for the generation of free radicals, which may contribute to the aforementioned alterations in the chemical and physical properties of the material [START_REF] Vilaplana | High-Impact Polystyrene During the First Use and Subsequent Recycling[END_REF].

Early works on the thermal-and photo-oxidation of ABS and HIPS revealed that the polybutadiene phase is selectively attacked during the initial stages of degradation, with hydroperoxide formation being the initiation mechanism [START_REF] Boldizar | Degradation of ABS during repeated processing and accelerated ageing[END_REF][133] [START_REF] Tiganis | Thermal degradation of acrylonitrilebutadiene-styrene (ABS) blends[END_REF]. The initial degradation of the PB phase leads to the progressive consumption of unsaturated groups and the formation of oxidated moieties. The reaction mechanisms are related to the chemistry of polybutadiene microstructures: cis-1,4, and trans-1,4 [START_REF] Saron | Dynamic mechanical spectroscopy applied to study the thermal and photodegradation of poly(2,6-dimethyl-1,4-phenylene oxide)/high impact polystyrene blends[END_REF]. As can be seen from Figure 6-1 above, hydrophilic oxygen-containing groups were introduced onto the plastic surface which made the surface more hydrophilic.

The carbon-oxygen single/double bonds make the molecule hydrophilic, they are typically charge-polarized and capable of hydrogen bonding, and have more thermodynamically favorable interactions with water and other polar substances than with oil or other hydrophobic solvents. This gives these plastics higher hydrophilicity.

Effect of additives

From the previous results of wettability measurements, effect of adding additives was found to be the same as the effect of oxidation.

If we only consider the chemical structures of ABS, HIPS and PP, neither HIPS nor PP contain hydrophilic molecules, while ABS has a carbon-nitrogen triple bond which is a polar bond, so ABS is slightly more hydrophilic than the other two plastics. This is supported/confirmed by the moisture content as well, at ambient atmospheric conditions the moisture content in ABS is higher than HIPS and PP. When 15% of bromine flame retardant TBBPA was added to all these plastics, contact angles of HIPS and PP were both reduced while contact angle of ABS increased slightly, this can be explained by the properties of TBBPA. TBBPA has two hydrogen bonds, indicating that it is hydrophilic molecule even if the hydrophilicity as not very obvious. When added to hydrophobic plastics such as HIPS and PP, the effect is the reduction of the original hydrophobicity. When added to ABS, which already has a polar bond, the replaced polar bond will influence surface hydrophobicity.

Concerning PP, to which with talc is added as an additive, the effect is the same. Talc, whose chemical formula is Mg3 Si4 O10 (OH)2, is also a hydrophilic molecule. When it is added to PP, it helps to reduce the material's surface hydrophobicity.

Correlation between contact angle and flotation recovery

In principle, selective flotation separation of plastics can be achieved by modifying surface properties of plastics or by using a liquid medium with a specific value of surface tension. Selective flotation in this process is mainly ascribed to the differences of plastics regarding the critical surface tension of wetting for the plastics. It is obvious that the depressive effect of the surfactant on the plastics is mainly a result of the reduced liquid surface tension. However, ABS, HIPS and PP talc have very close surface tension values, which makes it difficult to separate them by altering the liquid tension as the surface tensions of plastics are lower than that of water and the plastics are hydrophobic by nature.

Besides, it has been found that plastics flotation is controlled not only by surface chemical factors, but also by gravity factors. When plastics have similar density, as in our case, the larger contact angle is, the greater the floatability the plastic shows In the following part the correlation between contact angle value and flotation recovery is discussed.

Taguchi design

The Taguchi method is a statistical methodology which was developed and introduced by the quality control statistician Genichi Taguchi to improve the quality of manufactured items. It has been employed in numerous engineering applications. This method can be used for designing experiments to investigate how different parameters affect the mean target and determine the variance of a process-performance characteristic that defines how well the process is functioning [START_REF] Nevin | TAGUCHI METHOD AS A MEANS FOR EXTRACTING CAUSE AND EFFECT[END_REF].

Instead of having to test all possible independent variables in the Design of Experiments (DOE), the Taguchi method tests pairs of those variables [136][137]. This enables the collected data to be processed in such a way as to determine which parameters have the greatest effect on product quality with a minimum amount of experimentation or numerical simulation, thus saving time and resources [START_REF] Semioshkina | An overview on Taguchi Method[END_REF]. The Taguchi method is best used when there are an intermediate number of participating variables (3 to 50), few interactions between variables, and only a few of the variables contribute significantly [START_REF] Vuchkov | Quality Improvement with Design of Experiments: A Response Surface Approach[END_REF].

Taguchi matrix

The software Minitab was used to make Design of Experiment, the Taguchi design is used for the contact angle experiment and flotation recovery experiment, separately, then they will be compared to find correlation between them.

Application on contact angle experiments

In contact angle experiments, 5 factors were studied. Since it was conducted with a liquid and a solid, the solid part was divided into 3 aspects, called factor A, B and C. Factor A is the type of plastic, factor B is the effect of flame retardant, factor C is effect of oxidation, these three factors possess two levels, named 1 and 2.

Level 1 of factor A is ABS, level 2 of factor A is HIPS. Level 1 of factor B is neat plastic without TBBPA, level 2 of factor B is plastic filled with TBBPA. Level 1 of factor C is aged state, level 2 of factor C is virgin state. The liquid part consists of two factors: factor D and E. Factor D is the type of wetting agent factor E is their concentration, both of these two factors have three levels, named 1, 2, 3. Level 1 of factor D is NaCMC, level 2 of factor D is MC, level 3 of factor D is PVA. Level 1 of factor E is low concentration, level 2 of factor E is middle concentration, level 3 of factor E is high concentration.

There are 5 parameters, the highest number of levels is 3, so we will use a value of 3 when choosing our orthogonal array.

Using the array selector above, we find that the appropriate orthogonal array is 3^2, 2^3.

96

A B C D E 1 1 1 1 1 1 1 2 1 1 1 3 1 1 2 1 1 1 2 2 1 1 2 3 1 2 1 1 1 2 1 2 1 2 1 3 1 2 2 1 1 2 2 2 1 2 2 3 2 1 2 1 2 1 2 2 2 1 2 3 2 1 1 1 2 1 1 2 2 1 1 3 2 2 2 1 2 2 2 2 2 2 2 3 2 2 1 1 2 2 1 2 2 2 1 3
The figure 6-2 shows the plot for contact angle values: From these results, it can be seen that among the five factors, the order of their influence is: surfactant type>aging>concentration of surfactant>plastic type>addition of TBBPA. The influence of TBBPA is fairly low, it only has a delta of 0.12, while surfactant type and aging have highest influence on contact angle values, their deltas are more than 9. Therefore, it can be concluded that, during the wettability test in the previous work, surfactant type and aging of plastic had the highest influence, while the effect of TBBPA is not significant as the data module is expanded.

Therefore, the regression equation is as listed below, Contact angle value

Application to flotation experiments

In flotation experiments, 3 factors were studied. Factor A is the type of waste plastics, factor B is the type of wetting agents and Factor E is their concentration, all of these factors have three levels, named

Level 1 of factor A is ABS, level 2 of factor A is HIPS, level 3 of factor A is PP. Level 1 of factor B is NaCMC, level 2 of factor B is MC, level 3 of factor B is PVA. Level 1 of factor C is low concentration, level 2 of factor C is middle concentration, level 3 of factor C is high concentration.

There are 3 factors, the highest number of levels is 3, so we will use a value of 3 when choosing our orthogonal array.

Using the array selector above, we find that the appropriate orthogonal array is 3^3

Material Surfactant Concentration 1 1 1 1 2 2 1 3 3 2 1 2 2 2 3 2 3 1 3 1 3 3 2 1 3 3 2
99 The data in the table above is the average value of each parameter at each value, when level of plastic type is 1, it indicates ABS, 67.13% is the average of recovery values on ABS plastic in all experiments. Delta is the difference between maximum and minimum value with one factor, for example in factor B, plastics using NaCMC as surfactant is the level 1 of factor B, which is the maximum 88.64%, plastics using PVA as surfactant is the level 3 of factor B, which is the minimum 57.07%, and their difference value is 31.56%.

From these results, it can be seen that among the three factors, the order of their influence is: surfactant type> plastic type >concentration. The surfactant type influence has the highest effect on flotation recovery values, their deltas are about 30%. Therefore, it can be concluded that, during the flotation test in the previous work, surfactant type has highest influence on the results. Therefore, the regression equation is as listed below, Regression Equation in Uncoded Units: Recovery = 1.092 + 0.3737 A -0.6836 B + 0.1475 C -0.005161 A*A + 0.1710 B*B -0.03704 C*C -0.09756 A*B -0.07359 A*C Where, Factor A is types of plastic, factor B: surfactant agents, factor C: concentration of agents. With this equation, it is possible to predict the performance with other value of the factors.

Comparaison of Taguchi analysis between contact angle and flotation recovery of plastics

From the figure below, the trend of values of factor in contact angle and flotation recovery can be considered as the same. From the results above, it can be seen that in contact angle tests, the average contact angle value of ABS is smaller than HIPS, while in flotation experiments, the average recovery value of ABS is also smaller than that of HIPS. In contact angle tests, the average contact angle value of PVA is smaller than the other surfactants and the average contact angle value of NaCMC is higher than the others, while in flotation experiments, the average recovery value using PVA as surfactant is smaller than other surfactants and average recovery value using NaCMC as surfactant is again higher than other surfactants. This conclusion is also a confirmation of the conclusion in 6.1, illustrating that on the same material, its recovery value and its contact angle value are positively correlated.

Also, as shown in the regression model of contact angle and flotation recovery, the relation between the result and the factors can be mathematically expressed. The model is able to predict other situations, such as how the result will be influenced when concentration varies. The model is definitely possible to improve by more plentiful data from different factor levels and more digital expressed details of factors.

Conclusion and perspective

The previous litterature review showed that plastics waste has become one of the largest sectors in WEEE. Plastics recycling is important to the plastic industry, to energy saving and the environment. In this thesis, the state of the art of plastics in WEEE and flotation separation literature was presented and reviewed. Two main types of experiments were conducted: wetting on plastic specimens by surface determination (work presented in Chapter 4) studied the effect of parameters in wettability performance. Flotation separation (work presented in Chapter 5) experiments were conducted to study the effect of parameters in the separation process to find optimum conditions.

The analysis of the characteristics of plastics waste and the physical properties of plastics demonstrates that although several separation technologies (including optical sorting, sink-float separation and electrostatic separation) can be applied to separate mixed plastics, they generally have their limitations.

We have proposed the choice of materials that are ABS, HIPS and PP filled with 20% talc as they have similar densities and they are dark colored plastics. Also, they are the most presented in WEEE plastics. Since the traditional sorting methods have difficulties in treating these plastics, a new method is necessary to be studied in order to improve the sorting efficiency, so these plastics are one of our research items. Then, to conduct the flotation experiment, the surfactants are the essential reagents. After made the state of art, we have chosen three surfactants to be operated with. The experimental approach and preparation of samples are described, then the characterizations of samples are carried out by testing their densities, humidity and micrograph by SEM.

Then, the contact angles are tested. The objective of the contact angle experiment is to evaluate the wettability of each plastic, with or without some modification of the surface, to evaluate the possibility of modifying the wettability of materials with different surfactant agents, and to provide the optimized conditions for trying to separate these three plastics in subsequent flotation experiments. From the result we found that thermal aging has an effect on material surfaces, samples treated by thermal aging have smaller contact angles, indicating that they are more hydrophilic. Besides, the addition of bromine flame retardant and talc will also influence the hydrophobicity of material, making them more hydrophilic.

From the results, oxidation of plastics has a significant influence on wettability and will have effect on flotation separation; the addition of additives such as bromine flame retardant TBBPA and talc, both render the surface of plastic more hydrophilic. pH is found to be a possible parameter to improve the recovery of plastics with certain surfactants.

A statistical study of the results from chapter 4 and chapter 5 was studied to find the correlation between the two parts of experiments. The conclusion illustrated that recovery value and contact angle on the same material are positively correlated.

In the interpretation of results, a statistical idea is applied to establish the math model, the objective is to predict other situations when factors' data is modified. In addition, an MFA (Material Flow Analysis) case study was conducted to evaluate the improvement of plastic sorting by the flotation technique.

Nowadays plastics flotation is receiving increasing attention for plastics recycling, which reduces the negative effect of waste plastics on the environment and makes good use of the secondary resource. Adsorption of reagents is receiving more attention, and numerous efforts have been made on flotation separation of plastics, but fundamental studies reported on this subject are insufficient. Surface modification is a more feasible way/method to aid flotation separation of specific plastics. A combination of surface modification and adsorption of reagents can be an effective strategy for flotation separation of multi-component waste plastics. Also, a study integrating lifetimes and their distribution would provide a more accurate view of output flows in MFA study, more work needs to be done to quantify the loss in sorting processes.

However, there are several problems in the current situation, which need more study: with respect to techniques, there is a mismatch between industrial need and academic work; how plastic floatability can be rapidly evaluated; lack of on-line analysis. Therefore, more effort is necessary to establish an industrial application of plastics flotation, as bubble size, airflow rate and also the dimension of flotation cell are the important and pertinent elemement conduting the result of separation. There is also a need for an economic study of the implementation of flotation on a plastics sorting process, taking into account in particular the costs such as investment and operating costs of equipment, including accessorie equipment such as pumps, crushers, etc., the cost related to possible grinding, the costs of reagents and the costs of effluent treatment. Comme les plastiques sont des maté riaux trè s sensibles et sont basé s sur diffé rentes familles de polymè res, diffé rents additifs sont ajouté s de leur é laboration. Cela conduit à une grande diversité de plastiques et pose un frein sur le recyclage des produits en fin de vie. Les plastiques né cessitent une sé paration dans chaque famille de polymè res avant la ré gé né ration pour atteindre le taux de recyclage requis. Il existe plusieurs mé thodes pour trier les plastique, une procé dure de tri combiné e par plusieurs mé thodes de tri sera plus efficace.

Dans les centres de traitement, les diffé rents types de plastiques sont trié s principalement par deux technologies : le tri optique et la sé paration densimé trique. Le premier reconnaî t diffé rents types de polymè res en fonction de leurs spectres dans le proche infrarouge (NIR). La limite de la mé thode se situe principalement sur les couleurs tels que les plastiques de couleur sombre avec la transition basse. Les processus de la sé paration densimé trique est basé sur de leur diffé rence de densité . Ces techniques utilisent un milieu de procé dé de densité intermé diaire entre ceux des polymè res à sé parer. En gé né ral, la sé paration densimé trique est relativement simple mais devient difficile si les densité s des maté riaux sont trè s proches.

Pour les raisons ci-dessus, nous é tudierons la technologie suivante, qui est indé pendante des couleurs plastiques et moins influencé e par des densité s de plastique similaires.

Chapitre 2 Cas d'étude MFA (Material Flow Analysis)

La mé thodologie MFA est une mé thode analytique permettant de quantifier les flux et les stocks de matiè res ou de substances dans un systè me bien dé fini. Celle-ci est utilisé e pour é tudier les flux de maté riaux, de substances ou de produits dans diffé rents secteurs industriels ou au sein des é cosystè mes. Son emploi est trè s utile pour é tudier l'é conomie circulaire et ré aliser une bonne gestion des flux de matiè res. Le travail de thèse s'intéresse à gisement de PAM uniquement. Comme mentionné dans l'introduction générale, les deux technologies traditionnelles ont des limites, les plastiques de couleurs sombres et /ou ceux ayant des densité s similaires qui affectent le processus de sé paration, nous avons donc appliqué ces deux tris au rameau de gisement simplifié de flux de plastique dans PAM (figure 4), et celui-ci met en é vidence où se situe les pertes. La flottation peut remé dier à ces freins et de trier encore une partie des plastiques non trié dans un tri transitionnel et donc amé liorer le gisement. Bien qu'aujourd'hui le tri optique ait é té amé lioré pour trier tous les types de plastiques, nous pensons que d'autres procé dé s tels que notre technique proposé e sont essentiels pour amé liorer les taux de tri des plastiques. Par ailleurs, en ce qui concerne la viabilité é conomique de toutes les techniques de tri, la mé thode de flottation est rentable par rapport aux autres mé thodes.

Modè le et analyse

Préparation des matériaux pour l'expérimentation de flottation

Les é chantillons de plastique ont é té collecté s sous deux points: les plastiques vierges sont issus de la chute de la production dans le centre de traitement local et les plastiques en fin de vie ont é té collecté s dans une usine locale de dé mantè lement des DEEE. Pour faciliter l'é valuation des ré sultats de la flottation, les plastiques sé lectionné s é taient de couleurs diffé rentes selon chaque type de plastique.

Ce que nous avons collecté sont les morceaux en plastique issus des DEEE, nous les dé coupons d'abord en morceaux plus petits, puis les broyons à l'aide d'un broyeur é quipé d'un tamis de 10 mm. Les particules obtenues aprè s broyage ont é té classé es par tamisage en diffé rentes tailles de particules. Ceci a é té ré alisé pour obtenir des lots homogè nes pour les tests de flottation.

Caracté risation des é chantillons

La densité

La masse de l'é chantillon a é té mesuré e dans l'air et dans l'eau dé sionisé e avec une balance analytique, la densité est é gale à 𝜌 = 𝑚 𝑎𝑖𝑟 𝑚 𝑎𝑖𝑟 -𝑚 eau × 𝜌 eau 𝑇°mesure

Où mair et meau sont la masse de l'é chantillon dans l'air ou dans l'eau, et 𝜌 𝑤𝑎𝑡𝑒𝑟𝑇°measure est la densité de l'eau à la tempé rature de mesure. La tempé rature ambiante é tant de 20 ℃ alors la densité est de 998,2 kg/m 3 .

Microscopie é lectronique à balayage (MEB)

Le MEB a é té utilisé pour observer la surface des é chantillons de plastique. La figure 6 montre la morphologie MEB de l'ABS avant et après l'oxydation thermique. Il est apparu clairement que la rugosité de la surface avait changé après l'oxydation thermique. A la suite du l'oxydation thermique des é prouvettes plastiques, sa surface a é té endommagé e et sa rugosité a é té augmenté e. Lorsque l'on considè re un liquide sur une surface, il existe trois systè mes: le liquide, la surface et l'atmosphè re environnante, appelé vapeur. Les considé rations d'é quilibre permettent de calculer l'angle de mouillage à partir des tensions de surface, la relation entre les diffé rentes tensions de surface et l'angle de contact a é té donné e par Young dans l'é quation suivante. 𝛾 𝑆𝑉 = 𝛾 𝑆𝐿 + 𝛾 𝐿𝑉 cos 𝜃 𝐸𝑞1 où S, V et L se ré fè rent respectivement à la surface des substrats, à la vapeur et au liquide. γ est les forces qui sont les tensions d'interface entre les trois phases (S/L/G), θ est l'angle de contact, comme le montre la figure suivante. L'équation de Young dans la forme ci-dessus dé crit la situation d'équilibre lorsque les forces de tension de surface s'équilibrent.

Effet de nature de maté riaux

La mesure de l'angle de contact est d'évaluer la possibilité de modifier la mouillabilité des maté riaux avec diffé rents agents tensioactifs et donc les plastiques dans les expé rimentations de flottation.

Les plastiques de base utilisé s dans les expé rimentations sur les angles de contact sont l'ABS, le HIPS et le PP chargé de talc, les tensioactifs é tant le NaCMC, le MC et le PVA, comme mentionné dans le dernier chapitre. Afin de ré aliser l'objectif des expé rimentations, plusieurs paramè tres sont modifié s pour observer leur influence sur l'angle de contact. L'objectif principal de cette é tude expé rimentale est d'observer l'effet de l'addition de TBBPA sur ABS, HIPS et PP, la valeur mesuré e est de l'angle de contact pour la surface sans ou avec TBBPA. Les valeurs de l'angle de contact pour NaCMC sur la surface de HIPS pure sont toujours supé rieures à l'angle sur HIPS avec 15% de TBBPA, ceci n'est pas influencé par la concentration de NaCMC. Dans le cas de MC comme surfactant, l'angle de contact sur les HIPS avec TBBPA est plus petit que celui sur la surface HIPS sans TBBPA.

Une conclusion générale pour HIPS avec ou sans TBBPA est que, l'ajout de TBBPA dans le matériau a influencé la propriété de surface, se traduit par une diminution de l'hydrophobicité, les angles de contact ont donc é té influencé s. HIPS avec RFB possè dent un angle de contact plus faible, ce qui signifie un mouillage plus favorable à la surface.

La mê me expé rimentation a é té ré alisé avec PP.

Effet de l'oxydation thermique

L'objectif de cette section est d'observer l'effet du vieillissement sur les maté riaux. Nous avons expliqué la matrice des é chantillons, S1 à S4 sont utilisé s pour dé montrer l'effet du vieillissement sur des é chantillons basé s sur l'ABS. La mouillabilité de la surface des plastiques est largement dé terminé e par la morphologie de la surface et les groupes fonctionnels de surface. L'augmentation de la rugosité de surface et l'introduction de groupes hydrophiles contenant de l'oxygè ne tels que les groupes C-O et O-C=O sur la surface en plastique, qui devraient augmenter l'hydrophilie de surface. Lors de l'oxydation thermique Jusqu'à pré sent, nous pouvons conclure que le vieillissement a un effet sur la surface des é chantillons, en transformant leur surface en un maté riau plus hydrophile, pour cette raison, les angles de contact plus faibles sont observé s.

Effet de l'ajout du talc

L'objectif d'expérimentation de cette section est d'observer l'effet de l'ajout du talc sur les PP, cette formule est utilisé dans les PP pour ré duire le prix et augmenter. En conclusion, le talc a un effet sur la surface du PP, une teneur plus é levé e en talc rend la surface plus hydrophile.

Interpré tation des ré sultats

La variance des valeurs de l'angle de contact est une indication de l'é tat de la surface et de sa mouillabilité . Cette derniè re est largement dé terminé e par la morphologie de la surface et les groupes fonctionnels de surface. L'augmentation de la rugosité de surface et l'introduction de groupes hydrophiles contenant de l'oxygè ne tels que les groupes C-O et O-C=O sur la surface en plastique devraient augmenter l'hydrophilie de surface.

Dans nos expé rimentations, la variance est due principalement à deux effets : 1. l'oxydation (vieillissement thermique) 2. l'addition d'additifs, tels que les RFB et de talc Ces effets seront discuté s dans la section suivante.

Effet de l'oxydation

Il a é té prouvé que la dé gradation thermomé canique induite par de multiples traitements altè re le comportement rhé ologique et les proprié té s mé caniques de l'ABS et du HIPS, ces changements peuvent ê tre dus à la scission de la chaî ne dans la phase PS et à des modifications de la structure physique de la phase caoutchouc Les travaux pré cé dents sur la thermo-oxydation et la photo-oxydation de l'ABS et du HIPS ont ré vé lé que la phase de polybutadiè ne est attaqué e sé lectivement au cours des é tapes initiales de la dé gradation, la formation d'hydroperoxyde é tant le mé canisme d'initiation. La dé gradation initiale de la phase PB conduit à la consommation progressive de groupes insaturé s et à la formation de fractions oxydé es. Les mé canismes de ré action sont lié s à la chimie des microstructures de polybutadiè ne : cis-1,4 et trans-1,4.

Chapitre 5 Étude de la flottation

La flottation est une technique largement utilisé e de sé paration et de ré cupé ration dans les industries miné rales. Il s'agit d'un processus sé lectif de sé paration des miné raux en utilisant des agents tensioactifs. Le processus de flottation est utilisé pour sé parer une large gamme de sulfures, carbonates et oxydes avant de les affiner. Le phosphate et le charbon sont é galement traité s par la technologie de flottation.

Méthodologie d'expérimentation de flottation

Dans le but d'une application industrielle plus proche, l'eau utilisé e pour la flottation est l'eau du robinet. L'acide acé tique a é té utilisé pour ré guler le pH du milieu.

Les agents tensioactifs utilisé s sont la carboxymé thylcellulose sodique (NaCMC), la mé thylcellulose (MC) et le polyvinylalcool (PVA), basé s sur la litté rature et des recherches anté rieures sur la flottation. En plus, le terpiné ol é tait utilisé comme agent moussant. L'expérimentation est divisée en deux groupes, pour étudier séparément l'influence du vieillissement et l'efficacité de différents surfactants.

Ré sultats et discussion

Les ré sultats de l'expé rimentation de flottation sont exprimé s en termes de ré cupé ration en pourcentage dans les produits flottants. L'effet de la flottation peut ê tre observé visuellement tout au long de la ré cupé ration, les valeurs diffé rentes entre les taux de ré cupé ration des plastiques signifie le ré sultat de la sé paration, diffé rence é vidente signifie la meilleure sé paration é tant obtenue. La masse de chaque type de plastique flotté a é té pesé e aprè s le tri manuel du mé lange, la ré cupé ration du flotteur pour chaque plastique a é té calculé e par l'é quation ci-dessous.

Les donné es provenant des expé rimentations de MC montrent que l'effet de la dé pression augmente continuellement avec la croissance de la concentration de MC. Lors de l'ajout de MC comme surfactant, la ré cupé ration des plastiques obtenus est moindre et peut ê tre appliqué e à chaque type de plastique. Moins de ré cupé ration des plastiques HIPS obtenus par rapport aux plastiques ABS à la mê me concentration en tensioactif. En outre, on peut constater que les plastiques en fin de vie flottent toujours moins que les plastiques vierges, ce qui pourrait s'expliquer par la modification de la structure du polymè re aprè s vieillissement. Le vieillissement est un dommage pour les polymè res, il en coûte la rupture des liaisons chimiques et, avec l'oxygè ne, le C-O ou l'O-H se forme, ce sont des liaisons covalentes polaires typiques. Par consé quent, les polymè res aprè s oxydation deviennent plus hydrophiles qu'auparavant, sous l'influence d'agents tensioactifs, les surfaces plastiques hydrophobes sont plus attaché es aux bulles d'air que les surfaces plastiques hydrophiles.

Par consé quent, les polymè res aprè s oxydation deviennent plus hydrophiles qu'auparavant, sous l'influence d'agents tensioactifs, les surfaces plastiques hydrophobes sont plus attaché es aux bulles d'air que les surfaces plastiques hydrophiles. Ainsi, la flottabilité des produits en fin de vie est infé rieure à celle des produits vierges.

Effet de l'agent tensioactif

Dans cette section, les plastiques ABS, HIPS et les dé chets plastiques contenant 20% de talc remplis de talc ont é té sé lectionné s, dans chaque essai, nous avons pris un mé lange des plastiques constitué de 10g l'ABS, 10g HIPS et 10g PP talc. La séparation des déchets de plastiques mé langé s sur la base du type de polymè re n'est pas obtenue si aucun agent tensioactif n'est ajouté car les trois plastiques sont connus pour ê tre naturellement flottants lorsque l'air est introduit (hydrophobes). Par consé quent, il é tait né cessaire d'utiliser un agent tensioactif approprié pour obtenir une sé paration sé lective. La figure 18 montre que la ré cupé ration de l'ABS, de HIPS et de la PP avec des concentrations de NaCMC a varié jusqu'à 100 mg/L. Elle indique aussi que la ré cupé ration des plastiques ABS et HIPS est comprise entre 80% et 90%, la récupération des pp est proche à 100% sans l'ajout de tensioactif. À mesure que la concentration de NaCMC atteignait 25 mg/L, la ré cupé ration du PP et du HIPS diminuait alors que l'ABS restait pratiquement inchangé . La ré duction de la ré cupé ration est due à la diminution du surfactant, ce qui signifie qu'à une concentration de 25 mg/L, davantage de plastiques ont diminué que la concentration de 0. Cependant, lorsque la concentration a atteint 50 mg/ L, la ré cupé ration de l'ABS et du HIPS est passé e à 95 % et 96,4%, la ré cupé ration du PP est resté e sensiblement la mê me. Avec une addition supplé mentaire de NaCMC, la ré cupé ration de tous les plastiques reste au mê me niveau, indiquant que le contact entre les é chantillons de plastique et la NaCMC a atteint un é tat stable.

Les expé rimentations de flottation avec NaCMC n'ont pas produit la ré cupé ration et la pureté des produits souhaité es. Le cas optimal est à 50,75 et 100 mg/L que la NaCMC ne puisse pas sé parer l'ABS et le HIPS mais elle abaisse d'environ 20% le PP. La figure ci-dessus montre montre que lorsque la concentration de MC augmente à 25 mg/L, la ré cupé ration de tous les plastiques diminue et le HIPS est apparemment le plus affecté car la ré cupé ration chute de 90% à 40%. À la mê me concentration, 20% des ABS et des PP sont dé primé s, ce qui indique que davantage de HIPS sont dé primé s que les autres plastiques. Ensuite, la ré cupé ration de l'ABS diminue lé gè rement, la ré cupé ration de l'HIPS diminue lé gè rement de 10% et la ré cupé ration de la PP augmente lé gè rement de 2% respectivement lorsque la concentration augmente à 50 mg/L. Avec l'ajout supplémentaire de MC, la récupération de HIPS et de PP reste presque identique, tandis que l'ABS diminue continuellement.

MC est l'un des dé rivé s de la cellulose couramment utilisé comme dé presseur organique ou floculant dans la flottation des miné raux. Il est é vident que la diminution de la tension superficielle du liquide n'est pas la principale cause de l'effet dé primant du MC sur les plastiques, car la tension superficielle minimale de la solution MC est supé rieure à la tension superficielle solide des Les performances des expé rimentations de flottation avec MC é taient meilleures que les expé rimentations pré cé dentes avec MC, dans des conditions optimales, 88% de PP flotté et 38% de HIPS flottaient mais cela n'a pas produit la haute pureté souhaité e des produits. Des amé liorations ont ensuite é té mené es et les ré sultats pré senté s dans les paragraphes suivants.

Effet du pH

Comme les pré cé dentes expé rimentations de flottation n'ont pas permis de séparer complètement le mé lange, nous avons proposé un autre protocole expé rimental en é tudiant l'effet du pH du milieu de flottation. L'effet du pH a é té é tudié avec NaCMC. D'aprè s ce qui pré cè dent, les conditions optimales ont commencé à 50 mg/L. Ainsi, dans l'é tude du pH, la concentration à 50 mg/L a é té sé lectionné e. La ré cupé ration de l'ABS, du HIPS et du talc rempli de PP a é té calculé e et les ré sultats sont pré senté s dans la figure ci-dessous. La NaCMC s'est ré vé lé e ê tre un dé presseur efficace des deux plastiques sans ré duction significative de la tension superficielle. Le mé canisme de la dé pression est donc l'adsorption de la macromolé cule organique.

À un pH autour de 3, nous avons constaté qu'une dé pression sé lective de l'ABS é tait possible en utilisant une concentration et un temps de conditionnement fixes et que le talc de PP é tait davantage abaissé à plus de 90%. La dé pression inefficace sous alcalin se produit dans des conditions où la NaCMC sera complè tement ionisé e. Il est possible que les groupes anioniques ne soient pas facilement adsorbé s sur la surface en plastique chargé e né gativement. Au fur et à mesure que les conditions deviennent acides, la NaCMC commence à se convertir lentement en forme acide (HCMC) accompagné e d'une ré duction de la viscosité . Simultané ment, la solubilité est ré duite, ce qui peut avoir une incidence sur l'adsorption sur la surface en plastique. La lente conversion à la forme acide explique pourquoi le temps de conditionnement est une variable importante dans la flottation. Dans tous les cas, la sé paration des plastiques né cessite un contrôle des paramè tres pour obtenir une meilleue sé paration.

En gé né ral et le plus souvent, les mé langes de plastiques pré sentent des diffé rences insuffisantes dans leurs é nergies interfaciales pour permettre la sé paration par flottation. Dans de tels cas, une modification sé lective de la surface hydrophobe est né cessaire. Une mé thode de mouillage sé lectif est le conditionnement chimique. C'est un processus dans lequel l'adsorption des ré actifs sur les surfaces en plastique entraî ne une diminution de l'hydrophobicité de l'interface solide-liquide. Dans le processus de mouillage sé lectif, la mouillabilité des diffé rents types de plastiques est amé lioré e de maniè re sé lective. Le nombre pré dominant des groupes laté raux des chaî nes polymè res des plastiques est constitué par des hydrogè nes carboné s non polaires. C'est la raison des interactions principalement physiques entre les molé cules de la surface plastique et les molé cules dé pressives. La force d'interaction inclut la force dispersive de van-der-Waals ainsi que les liaisons hydrogè ne.

Certains polymè res contiennent des groupes laté raux polaires contenant de l'oxygè ne, de l'azote, du chlore ou d'autres atomes. De tels groupes laté raux permettent une interaction dipôle-dipôle van-der-Waals ainsi que des interactions Lewis-acide-base avec les dipôles des molé cules dé pressives.

La liaison chimique entre les polymè res de la surface plastique et les molé cules dé pressives est trè s rare, car les plastiques ont de faibles é nergies de surface et sont pratiquement inertes chimiquement dans l'environnement d'un procé dé de flottation.

Conclusion et perspective

La revue pré cé dente de la litté rature a montré que les dé chets plastiques sont devenus l'un des secteurs les plus importants des DEEE. Le recyclage des plastiques est important pour l'industrie du plastique, les é conomies d'é nergie et l'environnement.

Dans cette thè se, l'é tat de l'art des plastiques dans la litté rature sur les DEEE et la sé paration par flottation a é té pré senté et examiné . Deux principaux types d'expé riences ont é té mené es : le mouillage sur des é chantillons de plastique par dé termination de surface (travaux pré senté s au chapitre 4) a é tudié l'effet des paramè tres sur la performance de mouillabilité . Des expé riences de sé paration par flottation (travaux pré senté s au chapitre 5) ont é té mené es pour é tudier l'effet des paramè tres dans le processus de sé paration afin de trouver les conditions optimales.

L'analyse des caracté ristiques des dé chets plastiques et des proprié té s physiques des plastiques montre que, bien que plusieurs technologies de sé paration (y compris le tri optique, la sé paration par flottation et la sé paration é lectrostatique) puissent ê tre appliqué es pour sé parer les plastiques mé langé s, elles ont gé né ralement leurs limites.

Nous avons proposé le choix de maté riaux qui sont ABS, HIPS et PP remplis de 20% de talc car ils ont des densité s similaires et ils sont en plastique de couleur foncé e. Ils sont é galement les plus pré senté s dans les plastiques DEEE. Comme les mé thodes de tri traditionnelles ont des difficulté s à traiter ces plastiques, une nouvelle mé thode doit ê tre é tudié e afin d'amé liorer l'efficacité du tri, ces plastiques sont donc un de nos axes de recherche. Ensuite, pour ré aliser l'expé rience de flottation, les surfactants sont les ré actifs essentiels. Aprè s avoir fait l'é tat de l'art, nous avons choisi trois tensioactifs à utiliser. L'approche expé rimentale et la pré paration des é chantillons sont dé crites, puis les caracté risations des é chantillons sont effectué es en testant leurs densité s, leur humidité et leur micrographie par SEM.

Ensuite, les angles de contact sont testé s. L'objectif de l'expé rience de l'angle de contact est d'é valuer la mouillabilité de chaque plastique, avec ou sans modification de la surface, d'é valuer la possibilité de modifier la mouillabilité des maté riaux avec diffé rents agents tensioactifs et de fournir les conditions optimales pour essayer de sé parer ces trois plastiques dans des expé riences ulté rieures de flottation. À partir des ré sultats obtenus, nous avons constaté que le vieillissement thermique a un effet sur les surfaces des maté riaux, les é chantillons traité s par vieillissement thermique ont des angles de contact plus petits, ce qui indique qu'ils sont plus hydrophiles. De plus, l'ajout de retardateur de flamme au brome et de talc influencera é galement l'hydrophobicité des maté riaux, les rendant plus hydrophiles.

Figure 1 - 5

 15 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 1 - 8

 18 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 1 - 9

 19 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 1 -

 1 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 2 - 1

 21 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 2 - 2

 22 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 2 -

 2 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 2 - 4

 24 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 2 -

 2 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 3 - 1

 31 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 3 - 2

 32 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 3 - 3

 33 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 3 - 4

 34 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 3 - 5

 35 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 3 - 6

 36 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 3 - 7

 37 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 3 - 8

 38 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 3 - 9

 39 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 3 -

 3 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 3 -

 3 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 4 - 1

 41 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 4 - 2

 42 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 4 - 3

 43 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 4 - 4

 44 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 4 - 5

 45 Figure 1-1 European plastic converter demande by polymers types in 2016[5] ..........................Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6] .....Figure 1-3 Data overview of input, collect and treatment of residential WEEE in France ..........Figure 1-4 The objectives of recycling, reuse and valorization of each WEEE category[8] .......Figure 1-5 Proportion by material component of treated household WEEE ............................... Figure 1-6 Step of material sorting in WEEE treatment plant[14] ............................................... Figure 1-7 Densities of plastics [26] ............................................................................................Figure 1-8 Scheme of the electrostatic separator[30] ...................................................................Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31] ...........Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] . ..............................................................................................................................Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1] ..............Figure 2-2 Part of the MFA model without considering the new flotation technique .................Figure 2-3 2016 flows considering flotation technique ................................................................Figure 2-4 Overall flows of recycling plastics and wastes generated each year ..........................Figure 2-5 2006 to 2016 flows considering the new flotation technique .....................................Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79] ...................Figure 3-2 Structure of ABS molecules .......................................................................................Figure 3-3 Structure of HIPS polymer .........................................................................................Figure 3-4 Talc molecule structure[86] ........................................................................................Figure 3-5 Micrograph of Talc[87] ..............................................................................................Figure 3-6 Chemical structure of Tetrabromobisphenol A ..........................................................Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97] ...................................Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99] ................................................................................................................Figure 3-9 Structural formula of PVA .........................................................................................Figure 3-10 Production outline of PVA[104]............................................................................... Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation ........Figure 3-12 Micrograph of ABS before & after aging .................................................................Figure 4-1 Young's equation equates the surface tension forces at equilibrium .........................Figure 4-2 Examples of different wetting phenomenon ...............................................................Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116]. ...............................................................................................Figure 4-4 Schematic diagram of the Wilhelmy plate method[118] ............................................Figure 4-5 Schematic of Wilhelmy plate measurement cycle ......................................................

Figure 4 - 6

 46 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 - 7

 47 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 - 8

 48 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 - 9

 49 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 -

 4 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 -

 4 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 -

 4 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 -

 4 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 -

 4 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 -

 4 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 -

 4 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 -

 4 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 4 -

 4 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 - 1

 51 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 - 2

 52 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 - 3

 53 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 - 4

 54 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 - 5

 55 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 - 6

 56 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 - 7

 57 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 - 8

 58 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 - 9

 59 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 -

 5 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 -

 5 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 5 -

 5 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 6 - 1

 61 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 6 - 2

 62 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 6 - 3

 63 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

Figure 6 - 4

 64 Figure 4-6 Schematic running of a goniometer ............................................................................Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface ...............................Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface ............................................ Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface ................................................... Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface ........................................Figure 4-11 Contact angle of NaCMC on PP / PP fr surface .......................................................Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface.................................................Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface ............Figure 4-14 Contact angle of MC and PVA on ABS/ABS fr/aged ABS/aged ABS fr surface ...Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface ..........................................................................................................................................Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface ......................................................................................................................................................Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface ..........................................................................................................................................Figure 4-18 Example of calculation fitting model in Excel .........................................................Figure 5-1 Examples of plastic samples .......................................................................................Figure 5-2 Self designed glass flotation column ..........................................................................Figure 5-3 Effect of aging on ABS with NaCMC solution ..........................................................Figure 5-4 Effect of aging on HIPS with NaCMC solution .........................................................Figure 5-5 Effect of aging on ABS with MC solution .................................................................Figure 5-6 Effect of aging on HIPS with MC solution ................................................................Figure 5-7 Effect of aging on ABS with PVA solution ...............................................................Figure 5-8 Effect of aging on HIPS with PVA solution ...............................................................Figure 5-9 Effect of the three plastics from end of life with NaCMC solution ........................... Figure 5-10 Effect of the three plastics from end of life with NaCMC solution .........................Figure 5-11 Effect of the three plastics from end of life with PVA solution ...............................Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution .........................................................................................................................................Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution ....Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation ............................Figure 6-2 Plot for contact angle with each factor .......................................................................Figure 6-3 Plot for flotation recovery with each factor ................................................................Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery ..............

1

 1 Comparison of basic information on the existing sorting technologies ....................... Table 3-1 Characteristics of polypropylene ................................................................................. Table 3-2 Properties of Tetrabromobisphenol A .......................................................................... Table 3-3 Preparation matrix of samples concerning effect of oxidation and bromine flame retardant on wettability ................................................................................................................. Table 3-4 Preparation of PP with talc at different content ........................................................... Table 3-5 Results of plastics density test with contact angle samples ......................................... Table 3-6 Results of plastics density test with flotation samples ................................................. Table 3-7 Moisture content of samples ........................................................................................

ABS:

  Acrylonitrile butadiene styrene BFR: Brominated Flame Retardant DecaBDE: Deca brominated diphenyl ethers EoL: End of life FTIR: Fourier-transform infrared spectroscopy HBCD: Hexabromocyclododecanes HexaBB: Hexabromobiphenyl HIPS: High impact polystyrene LHA: Large household appliances MC: Methylcellulose MFA: Material flow analysis NaCMC: Sodium salt of carboxymethylcellulose NIR: Near infrared OctaBDE: Octa brominated diphenyl ethers PBB: Polybrominated biphenyls PBDE: Penta brominated diphenyl ethers PE: Polyethylene PentaBDE: Penta brominated diphenyl ethers POPs: persistent organic pollutants (POPs) PP: Polypropylene PS: Polystyrene PVA: Polyvinyl alcohol REACH: Registration, Evaluation and Authorization of Chemicals RoHS: Restriction of Hazardous Substances SEM: Scanning electron microscopy SHA: Small household appliances TBBPA: Tetrabromobisphenol A WEEE: waste electric & electronical equipment

Figure 1 - 1

 11 Figure 1-1 European plastic converter demande by polymers types in 2016[5]

Figure 1 - 2

 12 Figure 1-2 European plastics converter demand by segments and polymer types in 2016[6]

Figure 1 - 4

 14 Figure 1-4 The objectives of recycling, reuse and valorization 1 of each WEEE category[8]

Figure 1 - 5

 15 Figure 1-5 Proportion by material component of treated household WEEE

Figure 1 - 6

 16 Figure1-6Step of material sorting in WEEE treatment plant[START_REF] Ademe | Rapport Annuel Du Registre Des Déchets D'Équipements Électriques Et Électroniques[END_REF]

Figure 1 - 7

 17 Figure 1-7 Densities of plastics[START_REF]Density of Plastics: Technical Properties[END_REF]

Figure 1 - 8

 18 Figure 1-8 Scheme of the electrostatic separator[START_REF] Silveira | Application of triboelectrostatic separation in the recycling of plastic wastes[END_REF]

Figure 1 - 9

 19 Figure 1-9 Bubble-particle aggregates in (a) ores flotation and (b) plastics flotation[31]

Figure 1 -

 1 Figure 1-10 Adsorption mechanism of surface-active reagents at the surface of non-polar polymers[31] .

  Pascoe and O'Connell worked on flame treatment[62], Okuda et al. worked on ozonation treatment[63], N.Thi et al. worked on microwave treatment[64], Mallampati et al. worked on nano-metallic treatment[38], Guney et al. worked on thermal treatement[46], Wang et al. worked on alkaline

Figure 2 - 1

 21 Figure 2-1 Data overview of input, collect and treatment of SHA wastes in France[1]

Figure 2 - 2

 22 Figure 2-2 Part of the MFA model without considering the new flotation technique

Figure 2 -

 2 Figure 2-3 2016 flows considering flotation technique

Figure 2 - 4 40 Figure 2 - 5

 244025 Figure 2-4 Overall flows of recycling plastics and wastes generated each year

Figure 3 - 1

 31 Figure 3-1 Composition of plastics in WEEE, and the forecast of composition[79]

Figure 3 - 2

 32 Figure 3-2 Structure of ABS molecules

Figure 3 - 3

 33 Figure 3-3 Structure of HIPS polymer

Figure 3 - 4 Figure 3 - 5

 3435 Figure 3-4 Talc molecule structure[86]

Figure 3 - 6

 36 Figure 3-6 Chemical structure of Tetrabromobisphenol A

Figure 3 - 7

 37 Figure 3-7 Structural formula of sodium salt of carboxymethylcellulose (NaCMC) with labeled functional groups accessible for modification (carboxymethylation)[97]

Figure 3 - 8

 38 Figure 3-8 Repeating unit of methylcellulose: -OH or -OCH3 at positions 2, 3 and 6 of the anhydro-D-glucose[99]

Figure 3 - 9

 39 Figure 3-9 Structural formula of PVA

Figure 3 -

 3 Figure 3-10 Production outline of PVA[104]

  the sample after tested hours, 𝑤 𝑜𝑟𝑔 𝑖 is the original weight of the sample.

Figure 3 -

 3 Figure 3-11 FTIR of ABS (first) and HIPS (second) before (blue) & after (red) oxidation

Figure 3 -

 3 Figure 3-12 Micrograph of ABS before & after aging

Figure 4 - 1

 41 Figure 4-1 Young's equation equates the surface tension forces at equilibrium

Figure 4 - 2

 42 Figure 4-2 Examples of different wetting phenomenon

Figure 4 - 3

 43 Figure 4-3 Schematic of dynamic contact angle measurement by using (a) volume changing method and (b) tilting cradle[116].

Figure 4 - 4

 44 Figure 4-4 Schematic diagram of the Wilhelmy plate method[118]

Figure 4 - 5

 45 Figure 4-5 Schematic of Wilhelmy plate measurement cycle

Figure 4 - 7

 47 Figure 4-7 Contact angle of NaCMC on ABS/flame retardant ABS surface

Figure 4 - 8

 48 Figure 4-8 Contact angle of MC and PVA on ABS/ABS fr surface

Figure 4 - 9

 49 Figure 4-9 Contact angle of NaCMC on HIPS/HIPS fr surface

Figure 4 - 11 Figure 4 -

 4114 Figure 4-10 Contact angle of MC and PVA on HIPS/HIPS fr surface

Figure 4 -

 4 Figure 4-12 Contact angle of MC and PVA on PP/PP fr surface

Figure 4 -Figure 4 -

 44 Figure 4-13 Contact angle of NaCMC on ABS/ABS fr/aged ABS/aged ABS fr surface

Figure 4 -

 4 Figure 4-15 Contact angle of MC, NaCMC and PVA on HIPS/ HIPS fr/aged HIPS /aged HIPS fr surface

Figure 4 -

 4 Figure 4-16 Contact angle of NaCMC on PP filled with 20%talc and their aged samples surface

Figure 4 -

 4 Figure 4-17 below shows the evolution of measured value of contact angle for MC, NaCMC and PVA on PP surfaces: neat; 10% and 20% talc filled surfaces. The bar height corresponds to contact angle value. The blue bars represent neat PP surface, the green ones represent PP filled with 10% talc surface and the red ones represent PP filled with 20% talc surface.

Figure 4 -

 4 Figure 4-17 Contact angle of MC, NaCMC and PVA on PP filled with talc and their aged samples surface

  is x. As the reference liquids' polar and dispersive part of surface tension is already known, the values of y and x are also known. Therefore, the value of √𝛾 𝑠 𝑃 , which corresponds to m and √𝛾 𝑠 𝐷 , which corresponds to b can be calculated by the equation. Figure 4-20 is an example of calculation fitting model in Excel software.

Figure 4 -

 4 Figure 4-18 Example of calculation fitting model in Excel

Figure 5 - 1 Figure 5 - 2

 5152 Figure 5-1 Examples of plastic samples

Figure 5 - 3 Figure 5 - 4

 5354 Figure 5-3 Effect of aging on ABS with NaCMC solution

Figure 5 - 5 Figure 5 - 6

 5556 Figure 5-5 Effect of aging on ABS with MC solution

1 . 3 Figure 5 - 7 Figure 5 - 8 Figure 5 -

 1357585 Figure 5-7 Effect of aging on ABS with PVA solution

Figure 5 - 9

 59 Figure 5-9 Effect of the three plastics from end of life with NaCMC solution

Figure 5 -Figure 5 -

 55 Figure 5-10 Effect of the three plastics from end of life with NaCMC solution

Figure 5 -Figure 5 -

 55 Figure 5-11 Effect of the three plastics from end of life with PVA solution

Figure 5 -

 5 Figure 5-12 Effect of the three plastics from end of life with different pH in 50 mg/L NaCMC solution

Figure 5 - 13

 513 Figure 5-13 Effect on the three EoL plastics with different pH in 50 mg/L NaCMC solution

Figure 6 - 1

 61 Figure 6-1 Reactions of cis-1,4 and trans-1,4 isomers during the degradation

Figure 6 - 2

 62 Figure 6-2 Plot for contact angle with each factor

= 72 .

 72 38 -18.36 A + 0.99 B + 6.63 C + 1.21 D + 19.91 E -0.25 D*D -1.13 E*E + 8.77 A*B + 6.28 A*C + 1.79 A*D -3.55 A*E -8.89 B*C -0.48 B*D -0.68 B*E + 2.47 C*D + 0.13 C*E -5.50 D*E Where, Factor A: types of plastic Factor B bromine flame retardant (TBBPA) Factor C: oxidation Factor D: surfactant agents Factor E: concentration of agents In the following section, Taguchi design is used for flotation recovery values.

Figure 6 - 3

 63 Figure 6-3 Plot for flotation recovery with each factor

Figure 6 - 4

 64 Figure 6-4 Comparison of factors' influence on contact angle and flotation recovery

Fig 2

 2 Fig 2 Composition des DEEE

Fig 3

 3 Fig 3 Sché matisation des é tapes du traitement des DEEE (source ADEME)

Fig 4

 4 Fig 4 sché ma simplifié e de flux des plastiques dans PAM

Fig 5

 5 Fig 5 Partie du modè le MFA sans tenir compte de la nouvelle technique de flottation

Fig 6

 6 Fig 6 Partie du modè le MFA en considé rant la nouvelle technique de flottation

Fig 7 Micrographiques des surfaces des é chantillons 4 .

 4 Fig 7 Micrographiques des surfaces des é chantillons

Fig 8 L

 8 Fig 8 L'équation de Young assimile les forces de tension de surface à l'équilibre

Fig 9

 9 Fig 9 Angle de contact des tensioactif sur la surface de l'ABS et HIPS

Fig 10

 10 Fig 10 Angle de contact des tensioactifs sur la surface de PP

Fig 11

 11 Fig 11 Angle de contact sur la surface de l'ABS

Fig 12

 12 Fig 12 Angle de contact sur la surface de HIPS

Fig 13

 13 Fig 13 Angle de contact sur la surface du PP

Fig 14

 14 Fig 14 Ré actions des isomè res cis-1,4 et trans-1,4 pendant la dé gradation

Fig 15

 15 Fig 15 Photo de la colonne de flotation

Fig 18

 18 Fig 18 Évolution du taux de ré cupé ration des maté riaux avec NaCMC

Fig 19

 19 Fig 19 Évolution du taux de ré cupé ration des maté riaux avec MC

Fig 20

 20 Fig 20 Évolution du taux de ré cupé ration des maté riaux sous diffé rents pH

  de Pascoe, il a é té montré que la ré ponse de NaCMC é tait particuliè rement sensible au pH. Les ré sultats des expé rimentations de flottation avec une concentration fixe de NaCMC et un pH variable sont pré senté s sur la figure ci-dessous. On peut voir que la sé lectivité s'est amé lioré e dans la solution acide. Dans de telles conditions, les ré sultats obtenus avec un pH infé rieur sont reproduits sé paré ment dans la figure ci-dessous.

Fig 21

 21 Fig 21 Évolution du taux de ré cupé ration des maté riaux sous condition acide

D

  'aprè s les ré sultats obtenus, l'oxydation des plastiques a une influence significative sur la mouillabilité et aura un effet sur la sé paration par flottation ; l'ajout d'additifs tels que le TBBPA ignifuge au brome et le talc rendent la surface du plastique plus hydrophile. Le pH est un paramè tre possible pour amé liorer la ré cupé ration des plastiques avec certains surfactants.Une é tude statistique des ré sultats des chapitres 4 et 5 a é té é tudié e pour trouver la corré lation entre les deux parties des expé riences. La conclusion a montré que la valeur de ré cupé ration et l'angle de contact sur le mê me maté riau sont positivement corré lé s. Dans l'interpré tation des ré sultats, une idé e statistique est appliqué e pour é tablir le modè le mathé matique, l'objectif est de pré voir d'autres situations lorsque les donné es des facteurs sont modifié es. De plus, une é tude de cas MFA (Material Flow Analysis) a é té ré alisé e pour é valuer l'amé lioration du tri plastique par flottation.De nos jours, la flottation des plastiques fait l'objet d'une attention croissante pour le recyclage des plastiques, ce qui ré duit l'effet né gatif des dé chets plastiques sur l'environnement et fait bon usage de la ressource secondaire. L'adsorption des ré actifs fait l'objet d'une plus grande attention et de nombreux efforts ont é té faits sur la sé paration par flottation des plastiques, mais les é tudes fondamentales rapporté es à ce sujet sont insuffisantes. La modification de la surface est une mé thode plus faisable pour faciliter la sé paration par flottation de plastiques spé cifiques. Une combinaison de modification de la surface et d'adsorption des ré actifs peut ê tre une straté gie efficace pour la sé paration par flottation des dé chets plastiques multi-composants. En outre, une é tude inté grant les duré es de vie et leur ré partition permettrait d'avoir une vision plus pré cise des flux de production dans l'é tude d'AMF, il reste du travail à faire pour quantifier la perte dans les processus de tri.Cependant, la situation actuelle pose plusieurs problè mes qui né cessitent une é tude plus approfondie : en ce qui concerne les techniques, il y a un dé calage entre les besoins industriels et les travaux universitaires ; comment é valuer rapidement la flottabilité des plastiques ; l'absence d'analyse en ligne. Par consé quent, plus d'efforts sont né cessaires pour é tablir une application industrielle de la flottation des plastiques.Étude des mécanismesde flottation de mélanges de plastiques issus des DEEE Les Déchets 'Equipements Electriques et Electroniques (DEEE) contiennent des matières plastiques recyclables. L'efficacité du recyclage des plastiques dépend du tri amont réalisé au niveau de la fraction en mélange des résidus de plastiques. A cet effet, une analyse des flux de matières (MFA) relative au traitement des DEEE a été réalisée afin de montrer où se situent les problématiques de tri et de quantifier leur efficacité. Les technologies de tri les plus utilisées se heurtent à des limites qui compromettent leur efficacité : couleurs sombres, densités similaires, présence de retardateur de flammes bromés… Afin de remédier à ces problématiques de tri, ce projet de thèse s'intéresse à la flottation sélective en adaptant une technique de séparation de l'industrie minière au tri des plastiques. Cette technique consiste à modifier sélectivement l'hydrophobicité des matières à séparer à l'aide de tensio-actifs influant la mouillabilité des surfaces. Plusieurs facteurs tels que la nature des plastiques, leur état de surface, les tensio-actifs utilisés, leur concentration, … sont alors à considérer. Le travail expérimental a donc porté sur les phénomènes de mouillabilité des plastiques par détermination des angles de contacts et sur l'amélioration de la flottation sélective des surfaces en fonction de divers paramètres d'entrée. L'objectif final étant de déduire les conditions optimales de séparation. Enfin, une interprétation des résultats expérimentaux et un essai de modélisation ont an essential process in the recycling and valorizing of plastics from mixed plastic waste, has become increasingly important as the production and consumption of plastic products have continued to rise for many years. The currently used sorting technologies are mostly spectrum-or density-based, therefore lack the ability to separate plastics with dark colors and similar densities that are common in waste of electric and electronic equipment (WEEE). A material flow analysis (MFA) case study of plastics treatment is therefore implemented to show the problems of the sorting and to quantify their efficiency. This thesis study applied flotation, a wettabilitybased separation technique adapted from the mining in industry, in mixed plastics separation. The objective is to evaluate whether the modification on the surface of plastics by surfactant reagents would contributes to a better separation. The experiments were conducted to investigate the wettability of plastics. Among the parameters studied, oxidation of material is the most important. The scanning electron microscopy (SEM) reveals that the surface roughness changes on oxidized plastics. Besides, the flotation experiments were also carried out to improve the separation efficiency of the plastics. The optimum separation condition is determined by the study of parameters, such as reagent concentration, pH, and particle status. Finally, an interpretation of the results and a modeling test were given to justify the correlation of these results.

Table 4 -

 4 1 List of contact angles with deionized water on the samples .......................................Table 4-2 List of liquid tension of reference liquid ...................................................................... Table 4-3 Planning of plastic surface tension measurement ........................................................ Table 4-4 Results from surface energy test for different plastics ................................................. Table 6-1 Response Table for contact angle plot ......................................................................... Table 6-2 Response Table for recovery plot ................................................................................

  Waste products containing more than 0.25% PentaBDE were classified as hazardous waste. With reference to the Directive on Waste Electrical and Electronic Equipment (2002/96/EC) and the Directive restricting the use of certain hazardous substances in electrical and electronic equipment (2002/95/ECknown as RoHS), an agreement was reached to put an end to the use of BFRs in electrical and electronic equipment by 1 July 2006. Directive 2002/95/EC was followed by Commission Decision 2005/717/EC, which contains an exemption from the ban on the use of DecaBDE. In 2009, some BFRs were also added into the list of persistent organic pollutants (POPs) in the framework of the

The European Union (EU) performed risk assessment for penta and octa brominated diphenyl ethers according to the REACH Regulation (Registration, Evaluation and Authorization of Chemicals) Since 2004, Directive 2003/11/EC had prohibited the trading and use of PentaBDE and OctaBDE in products containing more than 0.1% of these substances by weight. Stockholm Convention. These restrictions relate to commercial mixtures of PentaBDE and OctaBDE. The same list already included another flame retardant, hexabromobiphenyl (HexaBB),

Table 1 -1 Comparison of basic information on the existing sorting technologies Sorting technology Advantage Disadvantage

 1

	Near infra-red	Rapid identification	Useless for dark objects
	Mid infra-red	Possible for sorting dark plastics	Identification might be slow and requires relatively appropriate surface.
	Fluorescence X	Identification of PVC and additives	Cannot identify other polymer families.
	Density separation	A low-cost separation method used for any material mixture of different densities	Purity is low for some plastics with similar densities, and long process.
	Tribo-electrostatic separation	Used for plastics of significantly different dielectric constant	Requires a dry and clean plastic surface

Table 3 -

 3

	1 Characteristics of polypropylene[88]
	Density (kg/m3)	890 to 910
	Melting temperature (℃)	130 to 170
	Glass transition temperature (℃)	-25 to -15
	Thermal conductivity (W/m/K)	0.22
	Heat capacity (J/kg/K)	1700
	Young's modulus in tension (MPa)	900 to 1700

Table 3 -2 Properties of Tetrabromobisphenol A

 3

	Name	Tetrabromobisphenol A
	Chemical formula	C15H12Br4O2
	Molar mass	543.9 g/mol
	Density	2180kg/m 3
	Melting point	178 °C
	Boiling point	250 °C
	Its main uses as an additive flame retardant are in acrylonitrile-butadiene-styrene (ABS) resins,
	high impact polystyrene and phenolic resins. Recommended starting levels of
	tetrabromobisphenol-A in ABS (medium to high impact) are 17.6-22.0% and 14% in high impact
	polystyrene[94].

Table 3 -3 Preparation matrix of samples concerning effect of oxidation and bromine flame retardant on wettability

 3

Table 3 -4 Preparation of PP with talc at different content

 3 Arts et Mé tiers (ENSAM), using polymer pellets and additive powder. For example, the neat ABS samples were made from ABS polymer pellets with the assistance of press, the ABS with flame retardant TBBPA samples were made from ABS polymer pellets and TBBPA powders with the assistance of press. All the samples are filled with 15% TBBPA.For thermal oxidation, the samples were put in a Memmert UE 200 climate chamber at 90℃ for 12 hours. The ageing temperature is chosen according to ISO 4892-2[105]. The samples were placed on a glass plate, taking less than 10% of total oven space, according to ISO188[106].

		10% Talc	20% Talc
	PP	S11	S12
	The samples, dimensions of which were 1mm*20mm*20mm, were fabricated in a laboratory of
	École Nationale Supé rieure d'

Table 3 -5 Results of plastics density test with contact angle samples

 3

					𝜌 𝑤𝑎𝑡𝑒𝑟 20 ℃	Density
			𝑚 𝑎𝑖𝑟 (g) 𝑚 𝑤𝑎𝑡𝑒𝑟 (g)	(kg/m 3 )	(kg/m 3 )
		Neat ABS	0.6951	0.0304	998.2 1043.853
	Samples	ABS with flame
	for	retardant	0.7253	0.0588	998.2 1086.263
	contact	Neat HIPS	0.6891	0.0224	998.2 1031.738
	angle tests	HIPS with flame
		retardant	0.7067	0.0422	998.2 1061.592

Table 3 -6 Results of plastics density test with flotation samples

 3

	Density
	(kg/m 3 )

𝑚 𝑎𝑖𝑟 (g) 𝑚 𝑤𝑎𝑡𝑒𝑟 (g)

𝜌 𝑤𝑎𝑡𝑒𝑟 20 ℃ (kg/m 3 )

Table 3 -7 Moisture content of samples

 3

Table 4 -1 List of contact angles with deionized water on the samples

 4

	Material	ABS	ABS fr	HIPS	HIPS fr	PP	PP fr
	Contact angle (°)	81.20	84.70	95.60	93.10	108.30	93.00
	Material	Aged	Aged	Aged	Aged	PP talc	PP talc
		ABS	ABS fr	HIPS	HIPS fr	10	20
	Contact angle (°)	83.40	76.30	83.20	81.20	100.70	93.70

Table 4 -2 List of liquid tension of reference liquid Reference liquid

 4

		γL(mN/m)	γL d (mN/m)	γL p (mN/m)
	Deionized water 72.8	21.8	51.0
	Diiodomethane	50.8	50.8	0.0
	Ethylene Glycol 47.7	30.9	16.8

Table 4 -3 Planning of plastic surface tension measurement

 4

	Reference liquid ABS	ABS fr 2	Aged ABS Aged ABS fr
	Deionized water	CA1a	CA2a	CA3a	CA4a
	Diiodomethane	CA1b	CA2b	CA3b	CA4b
	Ethylene Glycol	CA1c	CA2c	CA3c	CA4c

Table 4 -4 Results from surface energy test for different plastics

 4

		γs (mN/m)	γs D (mN/m)	γs P (mN/m)
	pp neat	25.4	25.4	0
	pp fr	40.68	40.32	0.36
	pp talc 10	25.6	23.7	1.9
	pp talc 20	34.6	16.2	18.4
	ABS neat	37.1	33.2	3.9
	ABS fr	38.5	36.2	2.3
	HIPS neat	33.2	32.6	0.6
	HIPS fr	40.7	40.3	0.4

Table 6 -1 Response Table for contact angle plot

 6 The data in the table above is the average value of each parameter at each value, for example, at level of plastic type, it indicates ABS, 80.61 is the average of all contact angle values on ABS plastic. Delta is the biggest value difference with one factor, for example, 4.81 is the delta of values of two levels of plastic type, equal to 85.43 minus 80.61; 9.49 is the delta of values of level 1 and level 3 of surfactant type, equal to 87.05 minus 77.56.

	Level Plastic type TBBPA Aging Surfactants Concentration of surfactant
	1	80.61	83.08 78.38	87.05	85.69
	2	85.43	82.96 87.67	84.45	82.81
	3				77.56	80.56
	Delta	4.81	0.12	9.29	9.49	5.13
	Rank	4	5	2	1	3

Table 6 -2 Response Table for recovery plot

 6

	Level	A	B	C
	1	0.6713 0.8864 0.7868
	2	0.6872 0.5943 0.6760
	3	0.6928 0.5707 0.5886
	Delta 0.0215 0.3156 0.1982
	Rank	3	1	2

1. Chapitre 1 État de l'art des plastiques issus de DEEE

  Ce travail de thè se consiste à adapter au tri des plastiques une technologie miniè re largement utilisé e lors de la concentration des minerais aprè s broyage. Cette technologie est appelé e : flottation par mousse. Les critères d'implémentation de ce procédé de tri sont significativement diffé rents pour les plastiques et ont un effet critique sur la qualité de la sé paration. A titre d'exemple, la mouillabilité des surfaces qui dépend de la nature des matériaux plastiques et de leur dégradation en surface, affecte l'efficacité de séparation d'un mélange de plastiques. Il convient donc de la caractériser et de la modifier en conséquence par l'emploi d'agents moussants dans la solution contenant le mélange de plastiques. La séparation qui s'en suit repose alors sur la modification de la mouillabilité des surfaces des plastiques. À l'aide d'agents moussants tels que les tensioactifs, les surfaces les plus hydrophobes auront plus d'affinités envers les bulles d'air qui viendront se coller à elles. Par consé quent, les plastiques les plus hydrophobes flotteront plus facilement sur le mé dium de flottation, tandis que les plastiques les plus hydrophiles couleront vers le fond de la cellule de flottation.A l'exception du tri PET/PVC (emballage), trè s peu de travaux sur le tri des plastiques par flottation sé lective ont é té ré alisé s en France. Au niveau du monde, la recherche sur la sé paration exacte entre HIPS et ABS est faible. En plus, aucune recherche sur l'élimination de PP talc excite dans la recherche actuelle. Ce constat justifie le caractère exploratoire et l'aspect novateur de cette thè se dont le dé roulé est pré senté dans ce mé moire de thè se.La première partie présente l'état de l'art relatif au traitement des plastiques issus des DEEE ainsi qu'au procédé de flottation sélective. S'ensuit une analyse des flux de matières (MFA) des plastiques issus des DEEE afin d'identifier et quantifier les gisements et les flux et retracer leur itiné raire tout au long de leur chaine de traitement. La troisiè me partie divisé e en deux chapitres concerne la présentation du dispositif d'étude, le protocole expérimental et la présentation des ré sultats. Enfin, une recherche des conditions optimales de sé paration par flottation est proposé e en fonction de critères tels que l'effet du vieillissement ou d'additifs dans les plastiques.la collecte sé lective des DEEE, avec des objectifs de collecte progressifs et une obligation de reprise gratuite de l'ancien appareil lors de la vente d'un nouvel appareil similaire ; le traitement systé matique de certains composants (condensateurs au PCB, cartes de circuits imprimé s, lampes à dé charge, etc.) et de substances dangereuses (mercure, CFC, etc.) pour pré venir toute pollution ; la ré utilisation, le recyclage, la valorisation des DEEE collecté s, avec des objectifs de recyclage et de valorisation é levé s, la priorité devant ê tre donné e à la ré utilisation d'appareils entiers.1.1.2 Classement par categorie d'equipementsLes EEE sont classé s par caté gories dé finies par la ré glementation. La transposition en droit franç ais de la nouvelle directive DEEE dé finit deux nouvelles classifications : la premiè re, qui comporte 11 caté gories et des sous-caté gories, est valable jusqu'au 14 août 2018, et à partir du 15 août 2018, 7 caté gories, plus proches des flux de collecte, seront à utiliser. Cette nouvelle classification permet de comparer plus facilement les types d'équipements collecté s par rapport aux é quipements mis sur le marché, qui seront à partir de 2018 classés dans l'une de ces sept catégories. Les DEEE ménagers sont composés en majorité de métaux tels que l'acier (métaux ferreux) qui repré sente 47.8 % tandis que les mé taux non ferreux (cuivre, cobalt, indium, tantale, etc.) repré sente 7.5% de la composition du DEEE. Quant aux plastiques et aux verres qui sont é galement des composants importants de ces dé chets, il entrent respectivement dans la constitution des plastiques pour 16.6 % et 10.1 %. La figure 2 illustre cette composition obtenue d'après une campagne de caractérisation réalisée pour le compte de l'ADEME.

	1.2 Traitement de DEEE en France
	1.2.1 Composition des DEEE
	666 682 tonnes de DEEE mé nagers et 55 267 tonnes de DEEE professionnels ont é té dé claré es
	traité es en 2016.
	1.1 Contexte ré glementaire
	1.1.1 Cadre ré glementaire europé en
	La directive 2002/96/CE, dite « directive DEEE », et la directive 2002/95/CE, dite « RoHS »,
	fixent le cadre ré glementaire europé en selon lequel sont organisé s, dans chaque État membre, la
	collecte sélective et le traitement des déchets d'équipements électriques et é lectroniques.
	La ré glementation DEEE impose notamment :
	-l'éco-conception des DEEE, pour favoriser le ré emploi et le traitement des DEEE ;

Fig 1 Catégories d'équipements

Les nouvelles catégories sont plus proches des flux de collecte, c'est-à -dire qu'elles correspondent davantage aux types de DEEE collecté s et traité s sé paré ment.

Tableau 1 Comparatif des techniques de tri pour le tri des plastiques

  Les polymè res sont formé s de grosses molé cules, composé es de nombreuses sous-unité s ré pé té es. Le plastique est fabriqué à partir de polymè res organiques synthé tiques ou semi-synthé tiques, ces polymè res organiques sont mallé ables et peuvent ê tre moulé s en objets solides de formes diverses. De nombreux polymè res organiques é tant trop rigides pour des applications particuliè res, ils sont mé langé s avec des additifs, ajouté s aux formulations pour les rendre plus flexibles, plus ré sistants ou plus faciles à manipuler. Les retardateurs de flamme aident à ré duire l'inflammabilité du maté riau.Né anmoins, il existe des substances dangereuses dans les retardateurs de flamme. Les retardateurs de flamme bromé s (RFB) gè rent la propagation de la flamme principalement grâ ce aux halogè nes qui capturent les radicaux libres. Cependant, les RFB peuvent augmenter la toxicité des incendies par la libé ration de sous-produits tels que les dioxines et les furannes bromé s et chloré s lors de la combustion. Les RFB s'accumuleront dans les corps humains et animaux, le problè me associé à leur biodé gradation dans l'environnement est lié au fait qu'ils contiennent souvent des composé s aromatiques qui sont gé né ralement ré sistants aux produits chimiques.Les PBB, les PBDE, les hexabromocyclododé canes (HBCD) et le té trabromobisphé nol A (TBBPA), ont é té produites en grande quantité dans le passé . Ensuite, comme un certain nombre de RFB ont é té trouvé s persistants dans l'environnement, des mesures lé gislatives ont é té prises pour mettre fin à leur production. L'Union europé enne a ré alisé une é valuation des risques pour les é thers diphé nyliques penta et octa bromé s conformé ment au rè glement REACH (enregistrement, é valuation et autorisation des produits chimiques; rè glement (CE) n ° 1907/2006). Depuis 2004, la directive 2003/11 / CE interdit le commerce et l'utilisation du pentaBDE et de l'octaBDE dans les produits contenant plus de 0,1% de ces substances en poids.

	1.3.2 Techniques du tri des plastiques
	Type de technique	Avantages	Inconvé nients
	Proche infra-rouge	Identification rapide stade	Ne dé tecte pas les plastiques de
		industriel	couleur sombre
	Moyen infra-rouge	Identification des	Sensible à l'état de surface,
		polymè re sombres	né cessite un traitement de longue
			duré e
	Fluorescence X	Identification de PVC et	Ne dé tecte pas les polymè res
		les additifs	sauf pour le PVC
	Tri densimé trique	Faible coût, stade	Pas adapté pour des densité s
		industriel	proches
	Flottation	Applicable pour tout	Procé dure complexe, stade
		mé lange des types des	laboratoire
		plastiques
	Tri triboé lectrique	Faible coût	Sensible à l'humidité et aux
			poussiè re

1.3 Matiè re plastique dans DEEE et les techniques de leur sé paration 1.3.1 Composition des plastiques

  MFA a é té utilisé afin d'estimer et d'é valuer les flux de matiè res plastiques gé né ré s par le PAM en France. Nous avons utilisé le logiciel STAN3 pour cartographier les flux de matiè re. Selon les donné es PAM recueillies, les taux de traitement et de tri suivants ont é té pris en compte pour modé liser tous les flux d'entré e et de sortie. Premiè rement, les matiè res plastiques de tous les flux d'entré e de PAM repré sentent 20,2% du poids total. Dans cette recherche, nous considé rerons que les 79,8% restants des autres maté riaux sont collecté s et é liminé s via d'autres processus de recyclage et que les 24% du poids total repré senté par les plastiques bromé s dans PAM seront trié s et inciné ré s. Les flux de plastiques non bromé s passent par des tables densimé triques pour séparer les principaux types de plastiques tels que le PP, le PC / ABS, le PMMA, l'ABS et le HIPS. Selon la litté rature, les plastiques dans PAM contiennent respectivement jusqu'à 29% et 26% d'ABS et de HIPS. En ce qui concerne le polypropylè ne, nous avons constaté dans la litté rature et les donné es recueillies que le PP chargé de talc repré sente jusqu'à 18% du poids total des polypropylè nes. Cette quantité sera trié e pour é limination. Ainsi, en traitant ces donné es, nous avons constaté que les quantité s non ré cupé ré es de PAM augmentaient encore considé rablement au cours des anné es et que les processus de tri et de recyclage actuels absorbent à peine ces flux. Pour cette raison, nous pré sentons une nouvelle technique de tri pour les plastiques à base de DEEE. Cette technique s'est révélée efficace lorsqu'il s'agit de trier les matières plastiques majeures. De plus, nous inté grons cette technique dans une MFA pour PAM afin de gé né rer l'augmentation du tri et donc le recyclage des flux de plastiques PAM.Dans le cadre de cette é tude, nous incluons é galement les techniques traditionnelles de tri. À cette é tape, nous considé rons que 59% des plastiques PAM sont de couleur claire, le reste est considé ré comme des plastiques de couleur foncé e. Les plastiques de couleur claire seront trié s en utilisant la technique de tri optique et les couleurs foncé es seront trié es en utilisant la sé paration par flottation. Les efficacité s de tri sont respectivement de 90% et 95% (retours de l'industrie franç aise).2.2 Ré sultats et discussionDans ce cas d'é tude, nous appliquons le MFA dans deux scé narios avant et aprè s la flottation est introduite dans le tri. Nous commençons par le scénario où la flottation n'est pas prise en compte. Comme dans la figure suivante, sans considé ration de la nouvelle technique de tri par flottation, seules 3 255,09 tonnes de matiè res plastiques pourraient ê tre recyclé es par sé paration par flottaison et tri optique à partir des flux de 2016.

			Mé taux
			ferreux
		GEM F 40%	40.2%
		GEM HF 16%	Mé taux non-ferreux 9%
	DEEE Traité	Écran 16& PAM 27%	Transformat eur 5.3% 12.5% Ré sidu	Couleur	Densité proche 61%	Traitement spé cial comme flottation	Z% traité (100-Z)% non recyclé
		Lampes 1% Panneaux photovoltaï q ue <1%	Plastique 20.2% Autre 12.8%	foncé 41%	Densité é loigné 39%	Tri densimé triqu e X% traité	Y% traité (100-Y)% non recyclé
				Couleur clair 59%	Tri optique	(100-X)%
						non recyclé
				122

3. Chapitre 3 Choix de maté riaux et sé lection de tensioactif en vue de la flottation

  Dans le travail de thè se, nous avons choisi trois matiè res plastiques, ABS, PS et PP remplies de 20% de talc. Les plastiques possè dent une densité proche ne peuvent pas ê tre sé paré s par une flottaison densimé trique, leur densité devrait ê tre supé rieure à 1000 kg/m 3 est parce qu'ils devraient être naturellement coulé dans l'eau pour que nous puissions gérer une séparation sélective, sinon ils seront tous flottés et il sera impossible d'réaliser le tri. Les plastiques sont des plastiques foncés est dû au fait que le tri optique, en particulier à l'aide de la technologie infrarouge, est trè s sensible à la couleur des maté riaux. De plus, d'aprè s un rapport de l'ADEME et d'autres cas d'étude, ABS, PS et PP sont les plastiques les plus repré senté s dans les DEEE.Le sodium de la carboxymé thylcellulose (NaCMC) est un polysaccharide liné aire non ramifié . NACMC est une poudre granulaire soluble dans l'eau, inodore et dont la couleur varie du blanc au blanc. NaCMC est un dé rivé utile de la cellulose avec diverses applications utiles dans les industries des dé tergents, du papier, des produits pharmaceutiques, etc. La mé thylcellulose est un composé chimique dé rivé de la cellulose. Il est l'un des nombreux dé rivé s de la cellulose couramment utilisé s comme dé presseur organique ou floculant dans la flottation miné rale. Préparation des matériaux pour l'expérimentation de mouillabilité L'objectif de l'expé rimentation de mouillabilité est d'observer la performance des agents tensioactif sur diffé rents maté riaux, afin d'é tudier la fonction de trois critè res, l'addition de RFB, l'oxydation et les types de polymè res.Les é chantillons utilisé s pour la mouillabilité sont des é prouvettes en plastique de 1 mm * 20 mm * 20 mm avec ou sans TBBPA, les é chantillons ont é té fabriqué s en laboratoire de l'ENSAM, en utilisant des granulé s de polymè re et de la poudre d'additif. Tous les é chantillons mé langé s de TBBPA sont à 15% du poids. Huit groupes d'é chantillons sont é numé ré s dans le tableau cidessous:

	3.1 Maté riaux plastiques utilisé s PP S9 S10 Idem pour les é chantillons de HIPS qui sont de S5 à S8, S5 est HIPS non vieilli et sans retardateur, x x S6 est HIPS non vieilli mais avec 15% de TBBPA ajouté , S7 est HIPS sans retardateur et vieilli, S8 est HIPS avec 15% de TBBPA et vieilli. Ensuite, pour observer l'effet de la teneur en talc dans le PP, une sé rie d'é chantillons a é té testé e, S9 est pur PP, S10 est PP avec 10% de talc en poids, S11 est PP avec 20% de talc en poids. De plus, le PP rempli de 15% de TBBPA est é galement testé . 3.3.1 Tableau 2 Groupes des é chantillons Au niveau du solide, ces é chantillons S1 à S12 ont é té utilisé s, au niveau du liquide, les trois
	Sans TBBPA agents tensioactifs ont é té utilisé s et leur concentrations ont varié s à trois niveaux pour chaque Avec TBBPA
	agent tensioactif.	ABS	G1		G2
		HIPS	G3		G4
		PP	G5		G6
			10% Talc	20% Talc
		PP	G7		G8
	Le vieillissement thermique des é prouvettes a é té effectué dans la cuve à 90 °C pendant 12 heures.
	Les agents tensioactifs ont é té pesé s puis dissous dans de l'eau dé sionisé e pour obtenir des
	solutions aqueuses à diffé rentes concentrations à l'aide d'un agitateur magné tique. Les
	é chantillons ont é té agité s pendant 24 heures à tempé rature ambiante.
	Les é chantillons suivent ces deux traitements, le vieillissement par thermique et l'ajout de
	retardateur de flamme bromé TBBPA. S repré sente l'é chantillon, S1 est l'ABS non vieilli et sans
	retardateur, S2 est l'ABS non vieilli mais avec 15% de TBBPA ajouté , S3 est l'ABS sans
	retardateur et vieilli, S4 est l'ABS avec 15% de TBBPA et vieilli.
			Tableau 3 plan des é chantillons
			BFR	Non BFR	Vieillissement Non vieilli
	ABS	S1		x	x
	Le polyvinyle alcool est fabriqué par polymé risation d'acé tate de vinyle monomè re en polyacé tate S2 x x
	de vinyle (PVAc), suivi d'une hydrolyse des groupes acé tate de PVAc en PVA. Il est largement S3 x x
	utilisé dans de nombreuses applications industrielles telles que le dimensionnement des textiles, S4 x x
	les adhé sifs, les colloï des protecteurs pour la polymé risation en é mulsion, etc. HIPS S5 x	x
		S6	x		x
	3.3 Demarche experimentale S7		x	x
		S8	x		x
			127

3.2 Agents tensioactifs appliqué s dans des expé rimentations

Les agents tensioactifs choisi sont sodium de la carboxymé thylcellulose (NaCMC), Mé thylcellulose (MC) et Polyvinyle alcool (PVA). Leur fonctionnement a é té justifié dans des recherches existé es.

  Les liaisons simple/double de l'oxygè ne du carbone sont des molé cules hydrophiles, elles sont gé né ralement polarisé es en charge et capables de liaisons hydrogè nes, ce qui a des interactions thermodynamiquement plus favorables avec l'eau et d'autres substances polaires que leurs interactions avec le pé trole ou d'autres solvants hydrophobes. Cela rend ces plastiques plus hydrophiles.4.3.2 Effet de l'addition des additifs D'aprè s le ré sultat pré cé dant sur la mesure de la mouillabilité , l'effet de l'addition de l'additif s'est ré vé lé ê tre le mê me que celui de l'oxydation.Si nous considé rons uniquement la structure chimique de l'ABS, du HIPS et du PP, les HIPS et PP ne contiennent pas de molé cules hydrophiles tandis que l'ABS possè de une triple liaison azote de carbone qui est une liaison polaire, de sorte que l'ABS est lé gè rement plus hydrophile. Lorsque tous ces plastiques ont é té additionné s de 15% de TBBPA, l'angle de contact du HIPS et du PP a é té ré duit alors que l'angle de contact de l'ABS a lé gè rement augmenté , ceci pouvant ê tre expliqué par la proprié té du TBBPA. Le TBBPA possè de deux liaisons hydrogè nes indiquant qu'il s'agit

d'une molé cule hydrophile, mê me si l'hydrophilie n'est pas trè s é vidente. Lorsqu'elle est ajouté e dans des plastiques hydrophobes tels que HIPS et PP, l'influence est la ré duction de l'hydrophobicité d'origine. Lorsqu'elle est ajouté e à l'ABS qui a dé jà une liaison polaire, la liaison polaire remplacé e influencera l'hydrophobicité de la surface.

En ce qui concerne le PP qui est ajouté avec du talc en tant qu'additif, l'effet est le mê me. Talc dont la formule chimique est Mg3Si4O10(OH)2 est é galement une molé cule hydrophile. Lorsqu'il est ajouté au PP, il aide à diminuer l'hydrophobicité de la surface des maté riaux.

  MC peut ré duire la tension superficielle du liquide à une valeur minimale de 56,7 mN / m. Par consé quent, l'effet dé presseur du MC sur les plastiques est principalement dû à son adsorption sur la surface en plastique. MC a de nombreux groupes polaires (groupe C-O et groupe O-H), les molé cules absorbé es sur la surface des plastiques exposent une partie de leurs groupes polaires orienté s vers la phase aqueuse, rendant ainsi la surface des plastiques hydrophile. En ce qui concerne l'interaction entre les surfaces en plastique et en plastique, il est é vident que la liaison chimique est trè s rare car les plastiques ont une faible é nergie de surface et sont pratiquement inertes chimiquement dans ce processus de flottation. En outre, l'interaction é lectrostatique peut é galement ê tre exclue, car MC est une substance non ionique. Par consé quent, l'adsorption est principalement due aux interactions de force de van-der-Waals.

	plastiques.
		100.00%
	recovery	60.00% 80.00%
	Flotation	20.00% 40.00%			EoL ABS EoL HIPS
		0.00%			Talc filled PP
		0	20	40 MC concentration(mg/L) 60 80	100	120
				141

Valorization: energy transform

fr: flame retardant

STAN (abréviation de subSTance flow ANalysis) est un logiciel gratuit permettant d'analyser les flux de matières conformément à la norme autrichienne Ö Norm S 2096 (analyse des flux de matières -Application à la gestion des déchets).

The Wilhelmy plate method is an excellent choice when dynamic contact angles on homogeneous, regularly shaped samples need to be measured, for example analysis of a single fiber, such as wetting of a hair, could be easily conducted by a sensitive force tensiometer.

Measurement method in wettability test

In the thesis study, the contact angle method is used among several methods presented before. It is due to the simplicity of conduction, and the samples' condition is suitable for this method, since these samples are specimens with flat surface and the material's composition is homogeneous on the samples. The contact angle is determined by placing the drop on a solid or other immiscible liquid. Then, the drop is illuminated by the light to produce an image with edges, which is reproduced on a black and white screen by a video camera.

The goniometer also has a direct and simple dosing system for the liquid, which operates with the help of a pressure exerted on a syringe. The volume and the speed of liquid dispensed are controlled by the software in the computer connected to the camera. With the software-controlled variant, the dosing dynamics can be accurately adjusted in order to make exact measurements of contact angles.

The following protocol was used to handle the measurements:

1. Start the SCA20 software on the computer and turn on the goniometer.

A1 Material composition and treatment process

Summary of the thesis in French

Étude des mé canismes de flottation de mé langes de plastiques issus de DEEE

Introduction gé né rale

Le recyclage des dé chets plastiques revê t une grande importance pour la protection de l'environnement tant du point de vue pollution que pré servation des ressources naturelles. Il permet en outre de ré duire la pollution engendré e par l'inciné ration des plastiques ou leur enfouissement et pire encore, leur abandon dans la nature. En effet, les diffé rentes familles de plastiques ne peuvent pas ê tre traité es en mê me temps et leur sé paration sous forme de tri devient alors un processus essentiel. Parmi les diffé rentes technologies de tri, deux sont couramment utilisé es : le tri par densité et le tri optique. Cependant, ces deux technologies ont des limites dont les principales sont respectivement, les plastiques de couleurs sombres et /ou ceux ayant des densité s similaires qui affectent le processus de sé paration. Bien entendu, d'autres limites au recyclage existent comme la pré sence de retardateurs de flamme bromé s dont la lé gislation fixe un seuil au-delà duquel il faut s'en séparer.

Un recyclage efficace né cessite de sé parer individuellement les polymè res afin de les isoler avant le processus de ré gé né ration. En outre, ceux-ci ne doivent pas ê tre trop dé gradé es afin de ré pondre au cahier des charges des granulateurs qui exigent des granulats de haute pureté . Aprè s avoir identifié les diffé rents verrous techniques concernant le tri des plastiques en é tudiant les pistes d'amélioration possibles, le procédé de tri par flottation sé lective a é té retenu. En effet, cette technique permet de ré soudre certaines problé matiques rencontré es par le tri optique et par densité et possè de un fort potentiel de dé veloppement à un cout é conomique raisonnable.

Recovery percentage = 𝑚 𝑓

𝑖 𝑚 𝑡 × 100%

où 𝑚 𝑓 𝑖 est la masse du plastique i (ABS, HIPS ou PP rempli de talc) dans les particules flottantes et mt est la masse originale de l'é chantillon de plastique sé lectionné e i.

Effet de l'oxydation des matériaux

Lorsque les é quipements arrivent en fin de vie, ils subissent des oxydations thermiques, de l'humidité ou des ultraviolets, ce qui conduit à des conditions de surface diffé rentes de celles d'origine. Les matières plastiques en fin de vie sont différentes des matières plastiques vierges en raison de la dé gradation de la surface des dé chets plastiques. Nous aimerions observer si ces modifications gé nè rent un effet sur la sé paration par flottation.

Le premier facteur é tudié est le vieillissement en cours d'utilisation. L'effet du vieillissement a é té é tudié à partir de deux types de plastiques: l'ABS et l'HIPS. Les comparaisons du taux de ré cupé ration de l'ABS vierge et de l'ABS en fin de vie, du HIPS vierge et du HIPS en fin de vie sont listé es ci-dessous. Chaque plastique a é té testé avec les trois surfactants en concentrations varié es, la figure 15 et la figure 16 montrent les ré sultats avec mé thyl cellulose.