PROCESS FOR DEGRADING PLASTIC PRODUCTS

Abstract

The present invention relates to a process for degrading a plastic product comprising at least one polymer, said process comprising the steps of at least partially foaming the plastic product; and depolymerizing at least one target polymer of the at least partially foamed plastic product, wherein the foaming step is carried out at a temperature at which the plastic product is in a partially or totally molten state.

Description

PROCESS FOR DEGRADING PLASTIC PRODUCTS The present invention relates to a process for degrading plastic products. The process of the invention particularly comprises a step of foaming a plastic product before depolymerizing at least one polymer of said plastic product. The process of the invention is particularly useful for degrading a plastic product comprising polyester and / or polyamide, preferably poly(ethylene terephthalate) and / or poly(lactic acid). The invention also relates to a process for producing monomers and / or oligomers from a plastic product that is at least partially foamed. BACKGROUND Plastics are inexpensive and durable materials that can be used to manufacture a variety of products for a wide range of applications (food packaging, textiles, etc.). Consequently, plastic production has increased dramatically in recent decades. Furthermore, most plastics are used for single-use, disposable applications, such as packaging, agricultural films, disposable consumer goods, or short-lived products that are discarded within a year of manufacture. Due to the durability of the polymers involved, substantial quantities of plastic are accumulating in landfills and natural habitats worldwide, creating increasing environmental problems.For example, in recent years, poly(ethylene terephthalate) (PET), an aromatic polyester produced from terephthalic acid and ethylene glycol, has been widely used in the manufacture of various products for human consumption, such as food and beverage packaging (e.g., bottles, mini soft drinks, bags for food items) or textiles, fabrics, mats, carpets, etc. Various solutions, ranging from plastic degradation to plastic recycling, have been studied to reduce the environmental and economic impacts associated with the accumulation of plastic waste. These include recycling technologies and energy production from plastics. Mechanical recycling remains the most widely used technology, but it faces several drawbacks. It requires extensive and costly sorting and leads to the deterioration of applications due to molecular weight loss during the process and the uncontrolled presence of additives in recycled products. Current recycling technologies are also expensive, so recycled plastic products are generally not competitive compared to virgin plastic. Recently, innovative enzymatic recycling processes for plastic products have been developed and described (e.g., in WO 2014 / 079844, WO 2015 / 097104, WO 2015 / 173265, and WO 2017 / 198786). Unlike traditional recycling technologies, these enzymatic depolymerization processes allow for the recovery of the polymer's chemical constituents (i.e., monomers and / or oligomers). The resulting monomers / oligomers can be recovered and used to manufacture new plastic articles, thus enabling the infinite recycling of plastics. These processes are particularly useful for recovering terephthalic acid and ethylene glycol from plastic products containing PET. However, there is always a need for processes with an improved degradation rate. SUMMARY OF THE INVENTION In working on improving the degradation processes of plastic products, the present inventors have demonstrated that the degradation stage can be enhanced by increasing the contact area between the plastic product and the degrading agent. The present inventors have thus created a process in which the surface area of ​​the plastic is increased before subjecting it to the degradation stage. More specifically, the present inventors propose subjecting the plastic product to a foaming stage before the depolymerization stage. Advantageously, the foaming stage increases the porosity of the plastic product and therefore increases the surface area available for contact with a degrading agent, thus promoting the subsequent depolymerization of one or more of the polymers that make up the plastic product.The methods of the invention are particularly useful for degrading plastic products comprising poly(ethylene terephthalate). In this regard, it is an object of the invention to provide a process for degrading a plastic product comprising at least one polymer comprising the steps of at least partially foaming the plastic product; and depolymerizing at least one target polymer of the at least partially foamed plastic product, wherein the foaming step is carried out at a temperature at which the plastic product is in a partially or totally molten state. Preferably, the foaming stage is carried out at a temperature higher than the crystallization temperature (Te) of the target polymer, preferably above the melting temperature (Tm) of said polymer and is implemented with a physical foaming agent and / or a chemical foaming agent. It is also an object of the present invention to provide a process further comprising a cooling step of the at least partially foamed plastic product, less than 30 seconds after the foaming step, by subjecting the plastic product to a temperature below the crystallization temperature (Te) of said polymer, preferably below the glass transition temperature (Tg) of said polymer. Advantageously, the process of the invention is carried out, at least partially, in an extruder. In one embodiment, the depolymerization step comprises bringing the plastic product into contact with a depolymerizing agent, selected from a chemical and / or biological depolymerizing agent. It is also an object of the invention to provide a process for degrading a plastic product comprising PET, comprising the steps of: a. foaming at least partially said plastic product with a foaming agent, preferably selected from a chemical foaming agent, wherein the foaming step is carried out at a temperature above 170 °C, preferably above 185 °C, more preferably above 200 °C, even more preferably above 220 °C, 240 °C, 245 °C, 250 °C, 255 °C, 260 °C, 265 °C. b. cooling said plastic product, at least partially foamed, to a temperature below 100 °C, preferably below 90 °C, less than 30 seconds after the foaming phase c. depolymerize the PET of the plastic product by bringing the plastic product into contact with the depolymerase, particularly an esterase, preferably a cutinase or a lipase, more preferably a cutinase. According to one embodiment of the invention, the plastic product is brought into contact with the depolymerase before the depolymerization step (for example, ORfr;nn / zznz / e / YiAi during the cooling stage) and the depolymerization stage comprises putting the plastic product in contact with a liquid that lacks depolymerase. According to another embodiment, the depolymerization stage involves subjecting the plastic product to composting conditions. It is also an object of the present invention to provide a method for producing monomers and / or oligomers and / or degradation products from a plastic product comprising at least one polymer, preferably PET, comprising successively subjecting the plastic product to a foaming step and a depolymerization step, preferably comprising exposing the plastic product to a depolymerase, preferably a cutinase. A further object of the invention is to provide a process for degrading an at least partially foamed plastic product comprising at least one polymer, wherein the at least partially foamed plastic product is contacted with a depolymerizing agent capable of degrading at least one target polymer, and wherein optionally said polymer has undergone a buffering step and the at least partially foamed plastic product is contacted with a depolymerase to degrade said polymer. DETAILED DESCRIPTION OF THE INVENTION Definitions This disclosure will be better understood with reference to the following definitions. In the context of the present invention, the terms "plastic article" or "plastic product" are used interchangeably and refer to any article or product comprising at least one polymer, such as a plastic sheet, tray, tube, rod, profile, mold, block, fiber, etc. Preferably, the plastic article is a manufactured product, such as rigid or flexible containers (bottles, trays, cups, etc.), agricultural films, bags and sacks, disposable or similar items, carpet scraps, fabrics, textile materials, etc. More preferably, "plastic article" refers to plastic or textile waste. Preferably, a plastic article comprises a mixture of semicrystalline and / or amorphous polymers. The plastic article may also contain additional substances or additives, such as plasticizers, minerals, organic fillers, dyes, etc. A polymer refers to a chemical compound or mixture of compounds whose structure consists of multiple repeating units (i.e., monomers) linked by covalent chemical bonds. In the context of the present invention, the term polymer refers to such a chemical compound used in the composition of a plastic product. As an example, synthetic polymers include petroleum-derived polymers such as polyolefins, aliphatic or aromatic polyesters, polyamides, polyurethanes, and polyvinyl chloride. In the context of the invention, polymer refers to a thermoplastic polymer, i.e., a polymer that becomes moldable above a specific temperature and solidifies upon cooling. The term depolymerization, in relation to a polymer or a plastic article containing a polymer, refers to a process by which a polymer or at least one polymer of said plastic article is depolymerized and / or degraded into smaller molecules, such as monomers and / or oligomers and / or any degradation products. According to the invention, oligomers refers to molecules containing from 2 to approximately 20 monomeric units. As an example, oligomers recovered from PET include methyl-2-hydroxyethyl terephthalate (MHET), bis(2-hydroxyethyl) terephthalate (BHET), 1-(2-hydroxyethyl)4-methyl terephthalate (HEMT), and dimethyl terephthalate (DMT). As another example, lactic acid oligomers can be recovered from PLA. In the context of the present invention, the term 'polyester' refers to a polymer containing the ester functional group in its main chain. The ester functional group is characterized by a carbon atom bonded to three other atoms: a single bond to another carbon atom, a double bond to an oxygen atom, and a single bond to another oxygen atom. The single bonded oxygen atom is bonded to another carbon atom. Depending on the composition of their main chain, polyesters can be aliphatic, aromatic, or semi-aromatic. A polyester can be a homopolymer or a copolymer. For example, poly(ethylene terephthalate) is a semi-aromatic copolymer composed of two monomers: terephthalic acid and ethylene glycol. In the context of the invention, crystalline polymers or semicrystalline polymers refer to partially crystalline polymers in which crystalline and amorphous regions coexist. The degree of crystallinity of a semicrystalline polymer can be estimated by different analytical methods and typically ranges from 10% to 90%. For example, calorimetry can be used. Differential scanning electron microscopy (DSC) or X-ray diffraction is used to determine the degree of crystallinity of polymers. Other techniques are also suitable for estimating polymer crystallinity, though with lower reliability, such as X-ray scattering (XS) (including narrow-angle and wide-angle XS) and infrared spectroscopy. In this disclosure, the degrees of crystallinity were measured using DSC. More specifically, the DSC measurements were performed as follows: a small amount of the sample (several mg) was heated at a constant heating rate from room or sub-room temperature to a high temperature above the melting temperature (Tm) of the polyester. Heat flow data were collected and plotted against temperature. The degree of crystallinity Xc (%) was calculated as: Xc(%) - AHcc) wt * AHf 100% x 100% where - ΔHί is the enthalpy of fusion that can be determined by integrating the endothermic fusion peak, - áHcc is the enthalpy of crystallization at low temperatures and is determined by integrating the exothermic peak of cold crystallization, - wt the weight fraction of polyester in the plastic and - AHt,ioo% is the enthalpy of fusion of a fully crystalline polymer and can be found in the literature. As an example, AHt,ioo% of PET is taken from the literature as 125.5 J / g (Polymer Data Handbook, second edition, edited by James E. Mark, Oxford, 2009). According to the literature, AHf,ioo% of PLA is equal to 93 J / g (Fisher EW, Sterzel HJ, Wegner G., Investigation of the structure of solution-grown crystals of lactide copolymers by means of chemical reactions, Kolloid Zeitschrift & Zeitschrift für Polymere, 1973, 251, pp. 980-990). The margin of error for the degree of crystallinity is approximately 10%. Therefore, a degree of crystallinity of approximately 25% corresponds to a degree of crystallinity between 22.5% and 27.5%. In the context of the invention, Tg, Te, and Tm refer to the glass transition temperature, crystallization temperature, and melting temperature of a polymer, respectively. These temperatures can be estimated using various analytical methods. For example, differential scanning calorimetry (DSC) or differential thermal analysis (DTA) can be used to determine the Tg, Te, and Tm of polymers. In this disclosure, the Tg, Te, and Tm of the disclosed polymers correspond to temperatures measured using DSC. Foaming stage The inventors have demonstrated that it is possible to improve the depolymerization rate of polymers contained in a plastic product, particularly polyesters, polyamides, and / or polyolefins, by subjecting the plastic product to a foaming step before subjecting one or more polymers to a depolymerization step. The foaming step increases the contact surface area between the polymer and the depolymerizing agent. In other words, by increasing the contact surface area between the plastic product and the degrading agent, it is possible to increase the depolymerization rate and / or reduce the amount of degrading agent and / or reduce the time required to degrade the plastic product compared to the same plastic product that has not been foamed. The invention relates particularly to plastic products comprising at least one thermoplastic polymer. According to the invention, the foaming step is carried out at a temperature at which the plastic product is in a partially or fully molten state. In particular, the foaming step is carried out at a temperature above the crystallization temperature (Te) of the target polymer of the plastic product (i.e., the polymer for which degradation or depolymerization is intended). Preferably, the plastic product is subjected to a temperature equal to or higher than the melting temperature (Tm) of the target polymer of the plastic product. Even more preferably, the plastic product is subjected to a temperature between Tm + 5°C and Tm + 25°C of the target polymer, preferably between Tm + 10°C and Tm + 25°C, more preferably between Tm + 15°C and Tm + 25°C, such as Tm + 20°C of the target polymer. In another embodiment, the plastic product is subjected to a temperature between Tm + 25°C and Tm + 50°C of the target polymer.In another embodiment, the plastic product is subjected to a temperature corresponding to the Tm + 50 °C of the target polymer or higher. According to one embodiment of the invention, the plastic product comprises several different polymers. In particular, the plastic product comprises at least the QRfr / nn / zznz / e / YiAi % by weight of the target polymer. In this case, the plastic product is advantageously subjected to a temperature equal to or higher than the Te or a temperature equal to or higher than the Tm of the target polymer. Alternatively, the plastic product is subjected to a temperature equal to or higher than the highest Te or Tm of the polymers contained in the plastic product. In one particular embodiment, the plastic product comprises PET, and the foaming step comprises subjecting the plastic product to a temperature above 170 °C, preferably above 230 °C, and more preferably to a temperature between 250 °C and 300 °C. Even more preferably, the plastic product comprising PET is subjected to a temperature between 260 °C and 280 °C. In another embodiment, the plastic product comprising PET is subjected to a temperature equal to or greater than 300 °C, preferably between 300 °C and 320 °C. In another particular embodiment, the plastic product comprises PLA and the foaming step comprises subjecting the plastic product to a temperature above 110°C and more preferably equal to or greater than 145°C. In another particular embodiment, the plastic product comprises PLLA and the foaming step comprises subjecting the plastic product to a temperature equal to or greater than 170°C. In another embodiment, the plastic product comprises PLA stereocomplex and the foaming step comprises subjecting the plastic product to a temperature equal to or greater than 230°C. As used herein, the foaming stage refers to a step in which cells (also called bubbles) are created in the structure of the plastic product through the use of foaming agents, also called blowing agents. The gas generated by these foaming agents creates bubbles within the molten or partially molten plastic material, forming closed and / or open cells in the plastic product. The resulting foamed plastic product has a cell structure and a lower density than the plastic product before the foaming stage. Foaming agents can be classified as physical foaming agents or chemical foaming agents, depending on how the bubbles are generated. According to the invention, the foaming step is implemented using one or more foaming agents selected from physical foaming agents, chemical foaming agents, and mixtures thereof. In one particular embodiment, the foaming step is implemented using one or more physical foaming agents. Alternatively, the foaming step is implemented using one or more chemical foaming agents. In another embodiment, the foaming step is implemented using one or more physical foaming agents and one or more chemical foaming agents. In the context of the invention, physical foaming agents refer to compounds that undergo a physical change of state during processing. Physical foaming agents include pressurized gases (such as nitrogen, carbon dioxide, methane, helium, neon, argon, xenon, and hydrogen, or mixtures thereof) that expand upon returning to atmospheric pressure during the foaming process, and low-boiling-point liquids (such as pentane, isopentane, hexane, methylene dichloride, and dichlorotetrafluoroethane) that expand when heated, changing from a liquid to a gaseous state and thus producing a greater volume of vapor. In one particular embodiment, the physical foaming agent is a gas. Preferably, the physical foaming agent is selected from the group consisting of nitrogen, carbon dioxide, argon, helium, methane, neon, xenon, hydrogen, or a mixture thereof. More preferably, the physical foaming agent is selected from carbon dioxide and nitrogen. In another embodiment, the physical foaming agent is selected from the group consisting of saturated aliphatic hydrocarbons, such as methane, ethane, propane, butane, pentane, and hexane; saturated alicyclic hydrocarbons, such as cyclopentane, cyclohexane, and ethylcyclopentane; aromatic hydrocarbons, such as benzene, toluene, and xylene; and halogenated saturated hydrocarbons, such as methylene chloride and carbon tetrachloride. ethers, such as methylal, acetal, 1,4-dioxane and ketones, such as acetone, methyl ethyl ketone and acetyl ketone or a mixture thereof.Alternatively, the physical foaming agent is selected from low-boiling liquids, specifically from the group consisting of pentane, isopentane, hexane, methylene dichloride, and dichlorotetrafluoroethane. In particular, the low-boiling liquid has a boiling point below the temperature at which the plastic product is in a partially or fully molten state. In one embodiment, the foaming step can be implemented using one or more of the physical foaming agents listed above. In a particular embodiment, the polymer of the plastic article subjected to a foaming step with a physical foaming agent has an intrinsic viscosity index greater than 0.5, preferably greater than 0.6. In one particular embodiment, the physical foaming agent is injected into the partially or fully molten plastic product. In other words, the plastic product is heated first, and when it melts, the physical foaming agent is injected into the molten material. In the context of the invention, chemical foaming agents refer to foaming agents that undergo a decomposition reaction upon heating the polymer to a given temperature, resulting in the release of gases such as nitrogen, carbon dioxide, carbon monoxide, nitroxide, NOx compounds, ammonia, and / or water vapor. Such chemical foaming agents may be selected from the group consisting of acids, hydracids such as p,p'-hydroxybis-(benzenesulfonylhydracid), semicarbacids such as p-toluenesulfonyl semicarbacid, azo compounds such as azodicarboxamide, triazoles such as nitrotriazolone, tetrazoles such as 5-phenyltetrazol, bicarbonates such as zinc bicarbonate or alkali bicarbonates such as sodium bicarbonate, anhydrides, peroxides, nitrogen compounds, and perchlorates.Alternatively, the chemical foaming agents are selected from citric acid, carbonate, bicarbonate, and mixtures thereof, or any commercial chemical foaming agent such as Clariant's HYDROCEROL® or Adeka's Orgater®. Preferably, the chemical foaming agents comprise a mixture of citric acid and carbonate and / or a mixture of citric acid and bicarbonate. Alternatively, the chemical foaming agent comprises hydrogen peroxide. In one embodiment, the foaming step can be implemented using one or more of the chemical foaming agents listed above. In a particular embodiment, the foaming step comprises a step of mixing one or more chemical foaming agents with the plastic product at room temperature and then subjecting the mixture to a temperature at which the plastic product is in a partially or totally molten state. In another embodiment, the chemical foaming agent is added to the plastic product while it is at least partially molten. In other words, the plastic product is heated first, and when it melts, the chemical foaming agent is mixed with the molten material. In one embodiment, the foaming stage is implemented with both one or more chemical foaming agents and one or more physical foaming agents. In one embodiment, the process of the invention comprises contacting 0.1 to 10%, preferably 0.1 to 5%, by weight of one or more foaming agents with 90% to 99.9%, preferably 95% to 99.9%, by weight of plastic product, depending on the total weight of the foaming agent / plastic product mixture. In particular, the process of the invention comprises contacting 0.1 to 10% by weight of a chemical foaming agent with 90% to 99.9% by weight of plastic product, depending on the total weight of the foaming agent / plastic product mixture. Preferably, the process of the invention comprises contacting 1 to 5% by weight of a chemical foaming agent with 95% to 99% by weight of plastic product.Alternatively, the process of the invention comprises contacting 0.1 to 5%, preferably 0.1 to 3%, more preferably 0.1% to 1%, by weight of a chemical foaming agent with 95% to 99.9%, preferably 97% to 99.9%, more preferably 99% to 99.9%, by weight of a plastic product. In another embodiment, the process of the invention comprises contacting 0.1 to 5% by weight of a physical foaming agent with 95% to 99.9% by weight of a plastic product, depending on the total weight of the foaming agent / plastic product mixture. Preferably, the process of the invention comprises contacting 0.1 to 3.5% by weight of a physical foaming agent with 96.5% to 99.9% by weight of a plastic product. In one embodiment, the foaming step is implemented with one or more foaming agents and a transforming agent, such as waxes, nucleating agents, chain extenders, foam boosters, or water, preferably water. In particular, the foaming step is implemented with one or more foaming agents and 0.01 to 10%, preferably 0.01 to 1% by weight, of a transforming agent, depending on the total weight of the foaming agent / plastic product / transforming agent mixture. Preferably, the foaming step is implemented with one or more chemical foaming agents and water, more preferably with a mixture of citric acid and water. In one embodiment, the foaming stage is carried out using an extruder, where the plastic product is subjected to a temperature at which it is in a partially or fully molten state. The foaming agent can be introduced into the extruder before heating, during heating, and / or after the material has been heated and is already in a molten state. In another embodiment, the foaming step is carried out by batch foaming in an autoclave, where the plastic product is saturated with a foaming agent and then subjected to sudden depressurization and optionally placed in a hot oil bath. As an example, the pressure-induced or temperature-induced method could be used. Batch foaming is particularly well-suited for a plastic product comprising at least one polymer and an additional component that could be subjected to degradation in an extruder (e.g., a composite comprising glass fiber or carbon fiber). Alternatively, the foaming and / or cooling stage can be performed using any technique known to an expert in the field. Advantageously, the plastic product before the foaming stage has a porosity rate of less than 10%, preferably less than 5%, and more preferably less than 3%. In one embodiment, the at least partially foamed plastic product has a porosity rate of between 20% and 90%, preferably between 25% and 50%. In particular, the porosity rate is between 30% and 40%. Alternatively, the plastic product has a porosity rate greater than 20%, preferably greater than 30%, and more preferably greater than 40%. As used herein, the term "porosity rate" refers to the void fraction in the plastic product and corresponds to the ratio of the volume of voids (i.e., pores) in the plastic product to the total volume of the plastic product. The porosity rate can be estimated by any method known to a person skilled in the art. Preferably, the porosity rate (t) of the plastic product is estimated using the following equation: waterT=l-^con: Pp -Pappaquees the apparent density of the foamed plastic product measured by pycnometry with water. -paguo. which is|a rea| ^θι plastic product based on its composition or measure in the unfoamed plastic composition. Particularly, the plastic composition is in the form of granules. Water pycnometry involves measuring the mass of a specific volume of water and the mass of the same volume containing both water and the foamed plastic product for which the density is to be determined. This allows for the determination of the sample's apparent density, providing access to the material's porosity rate, as long as the density of the original (i.e., unfoamed) plastic product (i.e., the true density) is known. For example, the true density of a plastic product comprising 100% PET, as found in the literature, is 1380 kg / m³, corresponding to the density of PET. The water pycnometry method is particularly well-suited for calculating the density of irregularly shaped products. In the case of regularly shaped products (e.g., cylinders), it is possible to directly calculate the product's volume and thus evaluate its apparent density.When the plastic product is a textile, the true density is based on the extruded but unfoamed textile composition (granule form). In one particular embodiment, the at least partially foamed plastic product comprises at least 95% PET and has an apparent density pa of less than 1000 kg / m3, preferably less than 900 kg / m3. In one embodiment, the at least partially foamed plastic product has a porosity rate of between 40% and 70% and an apparent density pappa of less than 1000 kg / m3. In one particular embodiment, the plastic product contains at least 95% PET and the at least partially foamed plastic product has an apparent density pappa of less than 1000 kg / m3 and a porosity rate greater than 30%. Preferably, the plastic product contains at least 95% PET and the at least partially foamed plastic product has an apparent density pa of less than 900 kg / m3 and a porosity rate greater than 30%, preferably greater than 40%. In one embodiment, the at least partially foamed plastic product is an at least partially foamed textile comprising at least 85% PET and having a porosity rate of between 10% and 70%. In one embodiment, the plastic product undergoes a pretreatment step before the foaming step. The pretreatment step may comprise sorting, washing, disinfecting, sterilizing, and / or biologically cleaning the plastic product before foaming. Alternatively or additionally, the pretreatment step may comprise physically transforming the plastic product into a film, flakes, powder, granules, or fibers before foaming. The process of the invention is particularly suitable for plastic products comprising PET. Therefore, an object of the invention is to provide a process for degrading a plastic product comprising at least PET, comprising a step of at least partially foaming said plastic product and a step of depolymerizing said PET from said at least partially foamed plastic product, wherein the foaming step is preferably implemented with a chemical foaming agent, more preferably with citric acid, carbonate, bicarbonate, and the same, more preferably with a mixture of citric acid and carbonate or with a mixture of citric acid and bicarbonate. As mentioned above, the present invention is particularly suitable for plastic products comprising thermoplastic polymers. The invention can also be implemented with plastic products comprising thermoset polymers by adapting the foaming step. Cooling stage In one particular embodiment, the process of the invention further comprises a cooling step of the at least partially foamed plastic product after the foaming step. As previously stated, the foaming step is performed with a plastic product that is heated to a molten state. According to one embodiment, after the foaming step, the foamed plastic product is subjected to a temperature lower than the temperature of the foamed plastic product itself, in order to rapidly reduce its temperature and accelerate its solidification. The cooling step comprises contacting the plastic product with any cooling fluid, including air and / or liquid. In one particular embodiment, the plastic product undergoes a cooling step less than 30 seconds after the foaming step, more preferably less than 20 seconds, and even more preferably less than 20 seconds. In particular, the plastic product undergoes a cooling step immediately after the end of the foaming step (i.e., heating). This rapid cooling after a heating phase allows for at least partial amorphization of one or more polymers in the plastic product. Amorphization occurs during the foaming stage (i.e., the heating stage), at least partially breaking down the crystalline structure of the polymers in the plastic product. Rapid cooling then fixes the heated polymer in an amorphous state. Therefore, polymer amorphization can be achieved during the foaming stage by subjecting the plastic product to a temperature above its melting point (Te), preferably above its melting point (Tm), and then rapidly cooling it to a temperature below its melting point (Te) and / or glass transition point (Tg). As used herein, the terms amortization and amortize, in relation to a polymer, refer to a decrease in the degree of crystallinity of a given polymer compared to its degree of crystallinity before amortization. Preferably, amortization allows the crystallinity of a target polymer to be reduced by at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 50%, 60%, 70%, 80%, or 90% compared to before amortization. Advantageously, amortization results in a polymer with a maximum of 30% crystallinity, preferably at most 25%, more preferably at most 20%, and even more preferably at most 15% crystallinity. Alternatively, amorphization allows the crystallinity of a polymer to be kept below 30%, preferably below 25%, more preferably below 20%, even more preferably below 15%.Amorphization can be carried out by any process known to those skilled in the art to at least partially break the crystalline structure of a polymer, and in particular any process described in WO 2017 / 198786. Amorphization thus increases the depolymerization capacity of said polymer by the biological agent. Foaming and cooling temperatures can be adjusted by a subject matter expert depending on the target polymer. Similarly, a subject matter expert knows when and / or how to perform degassing during the foaming stage, before and / or after the introduction of the foaming agent. QRfr / nn / zznz / B / YiAi Generally speaking, the plastic product can be subjected to heat treatment and, optionally, to shear stress for a period of time sufficient to achieve the desired shear rate of the target polymer. For example, this period of time can range from 10 seconds to several minutes, depending on the temperature and / or the plastic product. In a preferred embodiment, the foaming step comprises subjecting the plastic product to both shear stress and a temperature above the melting point (Te) of the target polymer, preferably at or above the melting point (Tm) of said polymer. The heating and shear stress are preferably carried out simultaneously to increase shear rate during the foaming step. According to the invention, the cooling step comprises subjecting the foamed plastic product to a temperature below the Te of the target polymer of the plastic product, preferably below the Tg of said polymer. Subjection to a temperature below the Te of the target polymer of the plastic product is particularly suitable for PBAT, for example, or any polymer whose Tg is below 20 °C. In another embodiment, the cooling is carried out by subjecting the heated plastic product to a temperature at least 20 °C below the Te of the target polymer, preferably less than 30 °C, 40 °C, or 50 °C. In one embodiment, the cooling is carried out by subjecting the plastic product to ambient temperature (i.e., 25 °C + / - 5 °C). In another embodiment, the cooling is carried out by subjecting the plastic product to a temperature of approximately 20 °C, or approximately 10 °C. Generally speaking, the plastic product is subjected to a cooling temperature for a period of time sufficient to lower the temperature at its core. For example, this period can range from 1 second to several minutes, depending on the initial temperature of the foamed plastic product (i.e., before the cooling stage) and / or the cooling temperature and / or the nature / shape of the plastic product. In one embodiment, the plastic product is in the form of an extrudate with a diameter of less than 1 cm, preferably between 0.5 and 5 mm, and is subjected to a cooling temperature for less than 1 minute, preferably less than 30 seconds, more preferably less than 20 seconds, and even more preferably less than 10 seconds. Alternatively, the foamed plastic material exiting the extruder is shaped into a tube or sheet. As an example, cooling can be achieved by immersing the plastic product in a liquid at the cooling temperature after the foaming stage. For instance, the at least partially foamed plastic product is immersed in a liquid at room temperature, more preferably at a temperature below room temperature, at the end of the foaming stage. For example, the plastic article is immersed in a cold liquid with a temperature below 14°C, preferably below 10°C or below 5°C. In one particular embodiment, the plastic product is immersed in cold water, such as water at 5°C or below. Alternatively, the plastic article is immersed in a liquid with a temperature below the Te of the target polymer. More generally, any suitable method for rapidly reducing the temperature of the plastic product (e.g., cold air) can be used. In a preferred embodiment, the foaming stage is carried out in an extruder. The extruder allows the plastic product to be subjected to a given temperature and shear stress, either simultaneously or sequentially. Advantageously, the foamed plastic product exiting the extruder is cooled directly by immersion and / or water spray. Advantageously, the extruder is selected from single-screw extruders, multi-screw extruders of co-rotating or counter-rotating design, planetary roller extruders, dispersive kneaders, reciprocating single-screw extruders (co-kneaders), mini-extruders, or internal mixers. In one embodiment, an underwater granulator or underwater strand granulator, which allows for cutting plastic material directly in cold water, is attached to the extruder head, resulting in the production of plastic granules that are immediately subjected to the cooling phase. In this embodiment, the plastic product is in the form of granules smaller than 1 cm, preferably between 0.5 and 5 mm, and is subjected to the cooling temperature for less than 1 minute, preferably less than 30 seconds, more preferably less than 20 seconds, and even more preferably less than 10 seconds. In particular, an underwater microgranulator that produces minigranules smaller than 1 mm is attached to the extruder head. Alternatively, the foaming stage is carried out in an autoclave, and the foamed plastic product is cooled by contact with ambient air or cooling air, or by immersion in a liquid at room temperature or below ambient temperature. Alternatively, the foaming and cooling stages may be performed using any technique known to a person skilled in the art. Therefore, it is an object of the invention to provide a process for degrading a plastic product comprising at least one polymer, comprising the steps of: a. foaming at least partially the plastic product wherein the foaming step is carried out at a temperature above the crystallization temperature (Te) of a target polymer of the plastic product, preferably above the melting temperature (Tm) of said polymer; and b. cooling said plastic product at least partially foamed to a temperature below the Te of said polymer, preferably below the glass transition temperature (Tg) of said polymer and c. depolymerizing said target polymer. Advantageously, the foaming agent is selected from chemical foaming agents. Preferably, the plastic product undergoes a cooling stage less than 30 seconds after the foaming stage, more preferably immediately afterward. Advantageously, the at least partially foamed plastic product is subjected to a granulation stage between the cooling stage (b) and the depolymerization stage (c), to obtain granules as described above. In one particular embodiment, the at least partially buffered and foamed target polymer exhibits a crystallinity rate of at most 30%, preferably at most 25%, and more preferably at most 20%. Preferably, the depolymerization step is carried out using a biological depolymerizing agent. In another embodiment, the extruder further comprises spinnerets for melt spinning of nonwoven products or for melt spinning of monofilaments or multifilaments, and the cooling stage is preferably carried out using cooling air. Therefore, it is another object of the invention to provide a process for degrading a plastic product comprising at least one polymer, comprising the steps of: ORfr;nn / zznz / e / YiAi temperature below 100 °C, preferably below 90 °C, preferably less than 30 seconds after the foaming stage; and c. depolymerize said PET. Advantageously, the foaming agent is selected from chemical foaming agents, preferably citric acid, carbonate, bicarbonate, or mixtures thereof, and / or the plastic product is subjected to a cooling stage less than 30 seconds after the foaming phase. Advantageously, the PET in the foamed product exhibits a crystallinity rate of less than 20% after the cooling phase, more preferably below 5%, and the depolymerizing agent is an esterase, preferably a cutinase, or a lipase, more preferably a cutinase. Depolymerization stage According to the invention, the degradation process comprises, after the foaming stage and the optional cooling stage, a depolymerization stage of at least one polymer of the plastic product. According to a preferred embodiment, the depolymerization stage targets at least one polymer that has been previously degraded. In a particular embodiment, the depolymerization step involves bringing the plastic product into contact with a depolymerizing agent, i.e., a chemical and / or biological agent. Advantageously, the depolymerization stage is carried out in a liquid medium comprising the depolymerizing agent. In another particular embodiment, the plastic product is brought into contact with a depolymerizing agent before the depolymerization step. For example, the plastic product is immersed, after the foaming step, in a liquid comprising the depolymerizing agent. In particular, the plastic product may be brought into contact with the depolymerizing agent during the cooling step (i.e., immersed in a coolant comprising a depolymerizing agent). In one embodiment, the depolymerization step is subsequently carried out by immersing the plastic product in a liquid. In a preferred embodiment, this liquid lacks the depolymerizing agent. In another embodiment, the depolymerization step is carried out by subjecting the plastic product to composting conditions.Specifically, the plastic product is subjected to industrial composting conditions at a temperature above 50°C and / or domestic composting conditions at a temperature between 15°C and 35°C. In one embodiment, the foamed plastic product is brought into contact with the depolymerizing agent during the cooling stage, and the depolymerization stage is implemented later by subjecting the plastic product to stimuli capable of activating the depolymerizing agent. For example, the depolymerizing agent is a degrading enzyme, and the stimuli consist of specific temperatures and / or humidity levels. In one particular embodiment, the depolymerizing agent is or comprises a biological agent. In particular, the biological agent is a depolymerase (i.e., an enzyme). Preferably, the depolymerase is capable of degrading at least one polymer of the plastic product, preferably at least one polymer that has been previously amoenabled. The depolymerase is advantageously selected from the group consisting of a cutinase, a lipase, a protease, a carboxylesterase, a p-nitrobenzylesterase, an esterase, an scl-PHA depolymerase, an mcl-PHA depolymerase, a PHB depolymerase, an amidase, an aryl-acylamidase (EC 3.5.1.13), an oligomer hydrolase, such as 6-aminohexanoate dimer cyclic hydrolase (EC 3.5.2.12), 6-aminohexanoate dimer hydrolase (EC 3.5.1.46), 6-aminohexanoate oligomer hydrolase (EC 3.5.1.B17), an oxidase, a peroxidase, a laccase (EC 1.10.3.2), an oxygenase, a lipoxygenase, a monooxygenase, or a lignolytic enzyme. In one particular embodiment, the plastic product is brought into contact with at least two different depolymerases. In one particular embodiment, the plastic product comprises PET and the depolymerase is an esterase. In particular, the depolymerase is a cutinase, preferably a cutinase produced by a microorganism selected from Thermobifida cellulosityca, Thermobifida halotolerans, Thermobifida fusca, Thermobifida alba, Bacillus subtilis, Fusarium solani pisi, Humicola insotens, Sirococcus conigenus, Pseudomonas mendocina, and Thielavia terrestris, or any functional variant thereof. In another embodiment, the cutinase is selected from a metagenomic library such as LC-Cutinase described in Sulaiman et al., 2012 or the esterase described in EP3517608, or any functional variant thereof, including the depolymerases listed in WO 2018 / 011284 or WO 2018 / 011281. In one particular embodiment, the depolymerase is a lipase preferentially produced by Ideonella sakaiensis. In another particular embodiment, the depolymerase is a cutinase. QRfr;nn / zznz / B / Ywi produced by Humicola templates, such as that with reference A0A075B5G4 in Uniprot or any functional variant thereof. In another embodiment, the depolymerase is selected from commercial enzymes such as Novozym 51032 or any functional variant thereof. In a particular embodiment, the plastic product comprises PLLA and the depolymerase is a protease, preferably produced by a microorganism selected from Amycolatopsis sp., Amycolatopsis orientalis, Tritirachium album (proteinase K), Actinomadura keratinilytica, Laceyella sacchari LP175, Thermus sp. or any commercial enzyme known to degrade PLA such as Savinase®, Esperase®, Everlase® or any functional variant thereof, including the depolymerases listed in documents WO 2016 / 062695, WO 2018 / 1 09183 or WO 2019 / 122308. In another particular embodiment, the plastic product comprises PDLA and the depolymerase is an esterase, preferably a cutinase or a lipase more preferably selected from OLE of Cryptococcus sp., PS lipase of Burkholderia cepacia, Paenibacillus amylolyticus TB-13, Candida Antarctica, Rhiromucor miehei, Saccharomonospora viridis, Cryptococcus magnus or any functional variant thereof. In another particular embodiment, the plastic product comprises PA and the depolymerase is selected from the group consisting of amidase, aryl-acylamidase (EC 3.5.1.13), oligomer hydrolase, such as 6-aminohexanoate cyclic dimer hydrolase (EC 3.5.2.12), 6-aminohexanoate dimer hydrolase (EC 3.5.1.46), 6-aminohexanoate-oligomer hydrolase (EC 3.5.1.B17). In another particular embodiment, the plastic product comprises polyolefin and the depolymerase is an oxidase preferably selected from the group consisting of laccase, peroxidase, oxygenase, lipoxygenase, monooxygenase or lignolytic enzyme. In another embodiment, the depolymerizing agent is a microorganism that expresses and excretes the depolymerase. This microorganism may synthesize the depolymerase naturally, or it may be a recombinant microorganism into which a recombinant nucleotide sequence encoding the depolymerase has been inserted, for example, using a vector. Specific embodiments of the depolymerization step can be found in WO 2017 / 198786. According to the invention, several microorganisms and / or purified enzymes and / or ORfr;nn / zznz / e / YiAi synthetic enzymes can be used together or sequentially to depolymerize different types of polymers contained in the same plastic article or in different plastic articles subjected simultaneously to the degradation process of the present invention. The time required to depolymerize at least one polymer in a plastic article can vary depending on the plastic article and the target polymer (i.e., the nature and origin of the plastic article, its composition, shape, molecular weight, etc.), the type and quantity of microorganisms / enzymes used, and various process parameters (i.e., temperature, pH, additional agents, etc.). A subject matter expert can easily adapt the process parameters to the specific plastic articles and / or depolymerases. In one particular embodiment, the plastic product comprises PET, and the depolymerization step is carried out by contacting the plastic product with a biological depolymerizing agent at a temperature between 20°C and 90°C, preferably between 30°C and 80°C, more preferably between 40°C and 75°C, more preferably between 50°C and 75°C, and even more preferably between 60°C and 75°C. Furthermore, the depolymerization step is preferably carried out at a pH between 5 and 11, preferably between 7 and 9, more preferably between 7 and 8.5, and even more preferably between 7 and 8. Alternatively, the depolymerization step can be carried out under industrial and / or composting conditions. In one particular embodiment, the plastic product comprises PLA, and the depolymerization step is carried out by contacting the plastic product with a biological depolymerizing agent at a temperature between 20°C and 90°C, preferably between 20°C and 60°C, more preferably between 30°C and 55°C, more preferably between 40°C and 50°C, and even more preferably at 45°C. Furthermore, the depolymerization step is preferably carried out at a pH between 5 and 11, preferably between 7 and 10, more preferably between 8.5 and 9.5, and even more preferably between 8 and 9. In another particular embodiment, the depolymerization step can be carried out at a pH between 7 and 8. Alternatively, the depolymerization step can be carried out under industrial and / or composting conditions. In another particular embodiment, the depolymerizing agent is or comprises a chemical agent. In particular, the chemical agent is a catalyst selected from QRfr / nn / zznz / e / YiAi stable and non-toxic metal catalysts or hydrosilane catalysts (PMHS, TMDS) such as commercially available B(C6F5)3 and [Ph3C+,B(C6F5)4-] catalysts. In particular, the catalyst is selected from alkoxide, carbonate, acetate, hydroxide, alkali metal oxide, alkaline earth metal, calcium oxide, calcium hydroxide, calcium carbonate, sodium carbonate, iron oxide, zinc acetate, or zeolite. In some embodiments, the catalyst used in the depolymerization process of the present invention comprises at least one of the following compounds: germanium, titanium, antimony, zinc, cadmium, manganese, magnesium, cobalt, silicon, tin, lead, or aluminum. In particular, the catalyst comprises at least one of germanium dioxide, cobalt acetate, titanium tetrachloride, titanium phosphate,titanium tetrabutoxide, titanium tetraisopropoxide, titanium tetra-n-propoxide, titanium tetraethoxide, titanium tetramethoxide, a tetrakis(acetylacetonate)titanium complex, a tetrakis(2,4-hexanedionate)titanium complex, a tetrakis(3,5-heptanedionate)titanium complex, a dimethoxybis(acetylacetonate)titanium complex, a diisopropoxybis(acetylacetonate)titanium complex, a di-n-propoxybis(acetylacetonate)titanium complex, a dibutoxybis(acetylacetonate)titanium complex, titanium dihydroxybisglycolate, titanium dihydroxybisglycolate, titanium dihydroxybislactate, titanium dihydroxybis(2-hydroxypropionate), lactate titanium, titanium octanediolate, titanium dimethoxybistriethanol aminate, titanium dimethoxybistriethanol aminate, titanium dibutoxybistriethanol aminate, hexamethyl dititanate, hexaethyl dititanate, hexapropyl dititanate, hexabutyl dititanate,hexaphenyl dititanate, octamethyl trititanate, octaethyl trititanate, octapropyl trititanate, octabutyl trititanate, octaphenyl trititanate, hexaalkoxy dititanate, zinc acetate, manganese acetate, methyl silicate, zinc chloride, lead acetate, sodium carbonate, sodium bicarbonate, acetic acid, sodium sulfate, potassium sulfate, zeolites, lithium chloride, magnesium chloride, ferric chloride, zinc oxide, magnesium oxide, calcium oxide, barium oxide, antimony trioxide, and antimony triacetate. Alternatively, the catalyst is selected from nanoparticles. The chemical agent can be selected from any catalyst. QRfr / nn / zznz / e / Ywi known by an expert in the field to have the ability to degrade and / or depolymerize the target polymer. Alternatively, the chemical agent is an acid or base catalyst capable of breaking polymer bonds, particularly ester bonds. Specifically, the chemical agent involved in breaking the ester bonds is a mixture of a hydroxide and an alcohol that can dissolve the hydroxide. The hydroxide is selected from alkali metal hydroxides, alkaline earth metal hydroxides, and ammonium hydroxide, preferably from sodium hydroxide, potassium hydroxide, calcium hydroxide, lithium hydroxide, magnesium hydroxide, ammonium hydroxide, or tetraalkylammonium hydroxide. The alcohol is selected from a linear, branched, cyclic alcohol, or a combination thereof, preferably a C104 linear alcohol from methanol, ethanol, propanol, or butanol. In one particular embodiment, the chemical agent is a mixture of a nonpolar solvent capable of swelling the polymer (i.e., a swelling agent) and an agent capable of breaking or hydrolyzing ester bonds, wherein the swelling agent is preferably a chlorinated solvent selected from dichloromethane, dichloroethane, tetrachloroethane, chloroform, tetrachloromethane, and trichloroethane. In another particular embodiment, the chemical agent is an acid selected from ethylene glycol, hydrochloric acid, sulfuric acid, or a Lewis acid. In one particular embodiment, the at least partially foamed and optionally cushioned plastic product may be subjected to cryogenic shredding, freeze-milling, freeze-shredding, or cryogrinding before the depolymerization step. In another embodiment, the plastic product is chopped or ground before the depolymerization step. Advantageously, the plastic product is not subjected to a micronization step before the depolymerization step. Plastic items The inventors have created a degradation process for breaking down plastic products comprising polymers, preferably thermoplastic polymers such as polyesters, polyamides, and / or polyolefins. The process of the invention can be advantageously used with plastic articles originating from plastic waste collection and / or post-industrial waste. More particularly, the process of the invention can be used to degrade household plastic waste, including plastic bottles, plastic trays, and bags. QRfr / nn / zznz / e / YiAi of plastic and plastic packaging, soft and / or hard plastics, even those contaminated with food residues, surfactants, etc. Alternatively, or in addition, the process of the invention can be used to degrade used plastic fibers, such as fibers from fabrics, textiles, and / or industrial waste. More particularly, the process of the invention can be used with PET plastic waste and / or PET fibers, such as PET fibers obtained from fabrics, textiles, or tires. Interestingly, the process of the invention allows for the production of monomers and / or oligomers and / or any degradation products that can be subsequently recovered and / or reprocessed. In one particular embodiment, the plastic product is selected from unfoamed plastic waste, including plastic bottles, plastic bags and plastic containers, soft and / or hard plastics, fibers, textiles, and / or foamed plastic products with a crystallinity greater than 30% comprising thermoplastic polymers. These foamed plastic products undergo a further foaming stage during heating and a cooling stage for cushioning before depolymerization. In one particular embodiment, the process of the invention is used to degrade a plastic product comprising at least one thermoplastic polymer, particularly a semicrystalline thermoplastic polymer. De manera ventajosa, el proceso de la invención se utiliza para degradar un producto plástico que comprende al menos un poliéster seleccionado de poli(tereftalato de etileno) (PET); poli(tereftalato de trimetileno) (PTT); poli(tereftalato de butileno) (PBT); poli(tereftalato de etileno con ¡sosorbida) (PEIT); poli(ácido láctico) (PLA); polihidroxialcanoato (PHA); poly(butylene succinate) (PBS), poly(butylene succinate adipate) (PBSA), poly(butylene adipate terephthalate) (PBAT), poly(ethylene furanoate) (PEF), polycaprolactona (PCL), poly(ethylene adipate) (PEA), polyethylene naphthalate (PEN), polycyclohexylene dimethylene terephthalate (PCT), polyethylene succinate (PES), poly(butylene succinate-coterephthalate) (PBST), poly(butylene succinate / terephthalate / isophthalate)-co(lactate) (PBSTIL) and combinations / mezclas of these polymers.En particular, el proceso de la invención se utiliza para degradar un producto plástico que comprende al menos un poliéster aromático seleccionado de poli(tereftalato de etileno) (PET); poli(tereftalato de trimetileno) (PTT); poli(tereftalato de butileno) (PBT); poli(tereftalato de etileno con ¡sosorbida) (PEIT); poli(adipato tereftalato de butileno) (PBAT), poli(furanoato de etileno) (PEF), y combinaciones / mezclas de estos polímeros. In a particular implementation, the process of the invention is used to degrade a plastic product which includes at least polyester and preferably at least PET or PLA. Alternatively, the process of the invention is used to degrade a plastic product comprising at least one polyamide selected from polyamide-6 or poly(P-caprolactam) or polycaproamide (PA6), polyamide-6,6 or poly(hexamethylene adipamide) (PA6,6), poly(11-aminoundecanoamide) (PA11), polydodecanolactam (PA12), poly(tetramethylene adipamide) (PA4.6), poly(pentamethylene sebacamide) (PA5.10), poly(hexamethylene azelaamide) (PA6.9), poly(hexamethylene sebacamide) (PA6.10), poly(hexamethylene dodecanoamide) (PA6.12), poly(m-xylene adipamide) (PAMXD6), polyhexamethylene copolymer adipamide / polyhexamethyleneterephthalamide (PA66 / 6T), adipamide / polyhexamethylene copolymer isophthalamide (PA66 / 6I) and combinations / mixtures of these materials. Alternatively, the process of the invention is used to degrade a plastic product comprising at least one polyolefin selected from polyethylene, polypropylene, polymethylpentene, polybutene-1, polyisobutylene, ethylene propylene rubber, ethylene propylene diene monomer rubber, ethylene vinyl alcohol, ethylene-carbon monoxide copolymer, and copolymers and modifications thereof. In one particular embodiment, the plastic product comprises at least two different polymers. More generally, the plastic products to which the process of the invention is directed may comprise different types of polymers, including synthetic polymers derived from petrochemicals such as polyamides, polyolefins, or vinyl polymers, or polymers of biological origin such as rubber, wood or wood compounds such as lignin, cellulose, or hemicellulose, and starch and derivatives thereof. Alternatively, the plastic product may comprise at least one polymer and an additional component, such as metal compounds, mineral compounds, glass compounds, natural or synthetic fibers (such as glass fibers or carbon fibers), paper, and derivatives thereof as defined in WO 2015 / 173265. Interestingly, the process of the invention allows the production of monomers and / or oligomers and / or degradation products that can be recovered and / or reprocessed later. Production of monomers / oligomers / degradation products It is also another object of the invention to provide a method for producing monomers and / or oligomers and / or degradation products from a plastic product comprising at least one polymer, comprising successively subjecting the plastic product to a foaming step to foam at least partially of said plastic product, optionally to a cooling step to depolymerize at least partially of said polymer from the plastic product, and then to a depolymerization step of said at least one polymer in the plastic product. Another object of the invention is to provide a process for degrading a plastic product comprising at least one polymer, wherein the plastic product has been previously foamed, the polymer of said plastic product has optionally been at least partially aerated, and wherein the plastic product is brought into contact with a depolymerizing agent capable of degrading said polymer, preferably a biological agent, more preferably a depolymerase. In one particular embodiment, the plastic product is depolymerized under composting or ambient conditions. In particular, the plastic product is subjected to industrial composting conditions at a temperature above 50°C and / or to home composting conditions at a temperature between 15°C and 35°C. In which case, the polymer of the plastic product can be degraded into water and / or carbon dioxide and / or methane by microorganisms in the compost and / or in the environment. Another object of the invention is to provide a process for degrading a plastic product, further comprising a purification step for the monomers and / or oligomers and / or degradation products resulting from the depolymerization step. The monomers and / or oligomers and / or degradation products resulting from depolymerization can be recovered sequentially or continuously. A single type of monomer and / or oligomer or several different types of monomers and / or oligomers can be recovered, depending on the starting polymers and / or plastic articles. The recovered monomers and / or oligomers and / or degradation products can be purified using any suitable purification methods and conditioned into a repolymerizable form. In a preferred embodiment, the repolymerizable monomers and / or oligomers can then be reused to synthesize polymers.An expert in the field can easily adapt the process parameters to the monomers / oligomers and polymers to be synthesized. Another additional object of the invention is to provide a method for recycling a plastic product containing at least one polymer, comprising successively subjecting said at least one plastic product to a foaming stage and a depolymerization stage and recovering monomers and / or oligomers from said polymer. It is also an object of the invention to provide a process for degrading a at least partially foamed plastic product comprising at least one polymer, wherein the at least partially foamed plastic product is produced from plastic waste and / or fiber waste and is brought into contact with a depolymerizing agent capable of degrading said at least one polymer, preferably a biological agent, more preferably a depolymerase. In particular, said at least partially foamed plastic product is obtained from plastic waste and / or fiber waste that has been previously subjected to a foaming step. In particular, said plastic waste and / or fiber waste has been subjected to a foaming step using chemical foaming agents or physical foaming agents or both chemical and physical foaming agents.In one particular embodiment, the at least partially foamed polymer of the plastic product is cushioned, and the at least partially foamed plastic product is brought into contact with a biological depolymerizing agent, preferably a depolymerase, to degrade the cushioned polymer. These foaming and cushioning steps can be carried out according to the particular embodiments described above. In particular, it is an object of the invention to provide a process for recycling a selected plastic product from plastic waste and / or fiber waste, comprising at least one polymer, wherein said plastic waste and / or fiber waste has been previously foamed, said process comprising a step of depolymerizing said at least partially foamed plastic product by contacting said product with a depolymerizing agent capable of degrading said at least one polymer, preferably a biological agent, more preferably a depolymerase. In one embodiment, ORfr;nn / zznz / e / YiAi The plastic product selected from plastic waste and / or fiber waste has been pre-foamed according to the specific embodiments described above. In particular, said plastic product has been pre-foamed using one or more chemical foaming agents or one or more physical foaming agents or both chemical and physical foaming agents. In one specific embodiment, said polymer of said plastic product has been pre-cureed before coming into contact with the depolymerizing agent, preferably a biological agent, more preferably a depolymerase capable of degrading said cureed polymer. In one embodiment, the plastic product selected from plastic waste and / or fiber waste has been cured according to the specific embodiments described above. Therefore, an object of the invention is to use a foamed plastic product comprising at least one polymer and to subject said foamed plastic product to a depolymerization step to produce monomers and / or oligomers of said polymer. Preferably, said foamed plastic product comprises plastic waste and / or fiber waste that has been previously foamed and whose polymer has optionally been pre-amortized. All the specific implementations described above in relation to the process for degrading plastic products also apply to the production methods of monomers and / or oligomers and to recycling methods. Production of biodegradable plastics Another object of the invention is to provide a plastic product comprising at least one target polymer and incorporating at least one enzyme capable of degrading said target polymer, wherein the enzyme has been incorporated into the plastic product according to the following process: a. foaming at least partially said plastic product with a foaming agent, preferably selected from a chemical foaming agent, wherein the foaming step is carried out at a temperature above the Te, preferably above the Tm of said target polymer b. cooling said plastic product at least partially foamed, less than 30 seconds after the foaming stage, by subjecting the plastic product to a liquid comprising a depolymerizing agent (i.e. an enzyme capable of degrading the target polymer), at a temperature below the Te and / or Tg of said target polymer. Additional aspects and advantages of the present invention will be disclosed in the following examples, which are to be considered illustrative and not limiting of the scope of this application. These examples provide experimental data supporting the invention and the means for carrying it out. EXAMPLES Example 1 - Degradation process of a plastic product comprising PET that includes a foaming stage performed with a chemical foaming agent A) Foaming stage with chemical foaming agent (CFA) and subsequent cooling stage a. With Clariant's HYDROCEROL PEX 5048 as CFA Washed and colored flakes of bottle waste composed of 98% PET with an average crystallinity value of 34.5% were foamed using a Leistritz ZSE 18 MAXX twin-screw extruder, comprising nine successive heating zones (Z1 - Z9) and a head (Z10) where the temperature can be independently controlled and regulated in each zone. The flakes were fed into the main hopper (before Z1). Clariant's HYDROCEROL PEX 5048 chemical foaming agent was fed into Z4 using a gravimetric feeder. A total flow rate of 3 kg / h was achieved, resulting in an extruded composition (S1) containing 4% CFA based on the total weight of that composition. The screw speed was set to 200 rpm. b. With citric acid as CFA Crushed and washed colored flakes composed of 98% PET with an average crystallinity of 34.5% were dry-mixed with 1% by weight of citric acid (Adeka Orgater exp 141 / 183) in powder form, based on the total weight of the mixture, resulting in an extruded foam composition (S1 BIS). The screw speed was set to 110 rpm and the total flow rate to 4 kg / h. The temperature profile along the spindle for sample preparation S1 and S1 BIS is described in Table 1. Table: Temperature profile of the extruder used for the sample called S1 and S1 BIS Sample Zone Z1 Z2 Ζ3 Z4 Ζ5 Ζ6 Z7 Ζ8 Z9 Ζ10 (head) S1 T°C 260 °C 260 °C 250 °C 250 °C 250 °C 250 °C 240 °C 240 °C 240 °C 240 °C S1 BIS TC 250 °C 260 °C 280 °C 280 °C 270 °C 260 °C 260 °C 230 °C 230 °C 230 °C The molten polymer reached the screw head (Z10), which consisted of a die plate with a 3.5 mm hole, and was immediately immersed in a 2 m long cold water bath (10 °C). The resulting extrudate was granulated into 2–3 mm solid granules (samples S1 and S1 BIS) with a crystallinity level of 0% and 1%, respectively. The porosity rate τ of each sample was calculated using the following equation: Pp” -paa^aque is the apparent density measured using pycnometry with water. -ρ^ηαque is the actual density measured in unfoamed polymer. The porosity rate τ of S1 is 33.6% and 54.6% for S1 BIS. Water pycnometry is determined as defined in the description using 4 to 5 extrusions 1 to 2 cm long, which corresponds to 1 to 2 g of material. A control sample, control-1, was extruded and granulated under the same conditions as S1 without the use of a foaming agent. Control-1 has a porosity rate τ of 0. Control-1 has a crystallinity level of 15%. A second control sample, control-2 (fine powder form), was prepared with a crystallinity level of 15% by immersing the granules from control-1 in liquid nitrogen and micronizing these granules using a RETSCH ZM 200 ultracentrifugal mill equipped with a 500 µm grid. Only the powder smaller than 500 µm obtained by sieving was used for the depolymerization step. B) Depolymerization stage of the foamed plastic product The depolymerization process was carried out in 500 ml minibioreactors (Global Process Concept, France) using a variant of LC-cutinase (Sulaiman et al., Appl Environ Microbiol. March 2012). This variant (LCCICCIG), corresponding to the enzyme of SEQ ID NO: 1 with the following mutations F208I + D203C + S248C + V170I + Y92G, was expressed as recombinant protein in Trichoderma reesei. 100 mg of an LC-cutinase variant prepared in 224 mL of 100 mM potassium phosphate buffer, pH 8, were combined with 56 g of PET samples. The temperature was regulated to 60 °C, and a marine turbine was used to restrict the stirring to a constant speed of 250 rpm. The pH was adjusted to 8 with 6 N NaOH and controlled using the GX controller with the C-BIO™ software (Global Process Concept, France). NaOH consumption was recorded during the process. The PET depolymerization rate was determined through periodic sampling. The samples were analyzed by ultra-high-performance liquid chromatography (UHPLC) to measure the amount of equivalent terephthalic acid produced according to the method described herein. The equivalent AT concentration was determined by ultra-high-performance liquid chromatography (UHPLC). If necessary, samples were diluted in 100 mM potassium phosphate buffer, pH 8. One milliliter of sample or diluted samples was mixed with 1 milliliter of methanol and 100 ml of 6 N HCl. After homogenization and filtration through a 0.45 µm syringe filter, 20 µl of sample were injected into the UHPLC system, Ultimate 3000 (Thermo Fisher Scientific, Waltham, MA), which includes a pump module, an autosampler, a column thermostated at 25 °C, and a UV detector at 240 nm. Terephthalic acid (TA) and the produced molecules (MHET and BHET) were separated using a methanol gradient (30% to 90%) in 1 mM H₂SO₄ at 1 m / min through a Discovery HS C18 HPLC column (150 mm x 4.6 mm, 5 pm) equipped with a pre-column (Supelco, Bellefonte, PA). TA, MHET, and BHET were measured using standard curves prepared from commercially available TA and BHET and from internally synthesized MHET.The AT equivalent is the sum of the measured TA and the TA equivalent in measured MHET and BHET. The percentage of hydrolysis of samples S2 and control2 was calculated based on the total amount of TA equivalent (TA + MHET + BHET) at a given time versus the total amount of TA determined in the initial sample. The results of the percentage of depolymerization are shown in Table 2 below. Sample Percentage of depolymerization (%) at 12h Control-1 2 Control-2 48 S1 60 SI BIS 65 Table 2: Depolymerization rate of PET from a foamed plastic product comprising PET (S1 and S1 BIS) compared to an unfoamed extruded plastic product (Control-1) and an unfoamed extruded and micronized plastic product (Control-2). The results show, firstly, that a foaming stage allows for a 30-fold increase in the PET depolymerization percentage compared to the unfoamed plastic product. Furthermore, the results also show that the process of the invention eliminates the micronization stage, as the foamed plastic product depolymerizes faster than the extruded and micronized plastic composition without foaming (Control-2). Example 2 - Degradation process of a plastic product comprising PET that includes a foaming stage performed with a physical foaming agent A) Foaming stage with carbon dioxide (CO2) and subsequent cooling stage Washed and colored flakes of bottle waste comprising 98% PET were foamed with supercritical CO2 using a single-screw extruder. This extruder (diameter 30 mm - SCAMEX, FRANCE) comprises six heating zones (T) where the temperature can be independently controlled and regulated in each zone: - T1 and T2: zones before CO2 injection, - T3 and T4: zones after CO2 injection, - T5: mixing zone comprising a static mixer and - T6: matrix comprising a matrix plate with an opening that can be adjusted according to the outlet pressure with a maximum opening of 3 mm. The temperatures at T1 to T3 are set at 180 °C, 280 °C, and 260 °C respectively, and the temperatures at T4 to T6 are listed in Table 3 below. The spindle speed was set to 40 rpm. The pressure at the end of the mixing zone (T5) is measured by a pressure sensor and is shown in Table 3 (P4). CO2 is pressurized and injected at a constant flow rate by a syringe pump (Isco 260D, USA) between T2 and T3. The pressure, temperature, and volumetric CO2 inlet (QCO2) at the pump are measured and shown in Table 3. The extrudates obtained are immediately immersed in fresh water at approximately 15 °C and then cut into 2–3 mm pieces using a blade mill. The resulting samples are then dried under ambient conditions for 48 h before analysis. Other experimental conditions used for sample preparation and the porosity and crystallinity results are shown in Table 3 below. Qp is the polymer flow rate, determined by weighing the resulting sample. Qco2 is the volumetric flow rate of injected CO2. The mass flow rate of CO2 relative to the total flow rate (WCO2) is calculated from the density obtained using the Span-Wagner equation of state (R. Span and W. Wagner, A new equation of state for carbon dioxide covering the fluid region from the triple-point temperature to 1100 K at pressures up to 800 MPa. Journal of Physical and Chemical Reference Data, vol. 25(6), pp. 1509-1596, 1996). Tmat is the material temperature measured at the extruder outlet. Sample T4 (°C) T5 (°C) T6 (°C) P4 (bar) Tmat3 Qp (g / min) QCO2 (ml / min) WC02 (%) water Papp (kg / m3) (%) Crystallinity (%) S2 255 255 255 117 241 18 0.35 1.8 741.4 46 20 S3 255 255 255 110 240 27.2 0.3 1.0 627.9 54 14 S4 240 240 240 107 229 19.4 0.5 2.4 664.9 51 9 S5 230 230 230 124 219 17 0.3 1.7 804.3 41 13 Table 3: Experimental conditions used for the preparation of foamed plastic products using a physical foaming agent and porosity and crystallinity results B) Foaming stage with nitrogen (N2) and subsequent cooling stage The extrusion-foaming stage was carried out using a single-screw extruder (45 mm diameter, FAIREX) comprising a melt cooler, a static mixer, and a vertical die with a nominal diameter of 2 mm. A PROMIX gas injection system was used to introduce supercritical N2. A 2 m long cold water bath (9 °C) was used to cool the extrudate before granulation with a rotary cutter to obtain 1.5 mm long granules. The distance between the die outlet and the water surface was approximately 5.5 cm. Washed and colored flakes of bottle waste containing 95% PET (43% crystallinity) were dried at 80 °C. The set temperature and recorded material parameters are shown in Tables 4 and 5 respectively. The spindle speed was set to 25 rpm. The total material flow rate was 6 kg / h and the injected nitrogen flow rate was 15 g / h. The resulting S6 granules were then dried at room temperature for 48 h before analysis. T1 (°C) T2 (°C) T3 (°C) T4 (°C) T5 (°C) T Melting Cooler (°C) T Static Mixer (°C) T Mathz (°C) 240 245 250 250 250 240 245 215 Table 4: Set of temperatures in the extruder End of spindle Static mixer outlet Pressure (bar) Temperature (°C) Pressure (bar) Temperature (°C) 146 223 126 217 Table 5: Material parameters recorded at the end of the screw and at the outlet of the static mixer The Pap?ade of sample S6 was evaluated at 461.7 kg / m3, which provides a porosity rate of 66%. Its crystallinity level was evaluated at 14%. C) Depolymerization stage The same recombinant secreted LCC-ICCIG enzyme used in Example 1 was used for the subsequent depolymerization of samples S2 to S6 and control-1 (produced as in Example 1). For each sample S2 to S6 and control-1, 100 mg were weighed and placed into a 250 mL glass bottle containing 49 mL of 0.1 M potassium phosphate buffer (pH 8). Depolymerization was initiated after the addition of 1 mL of enzyme solution at 0.1 mg / mL in 0.1 M potassium phosphate buffer (pH 8) by incubating each sample at 60 °C and 150 rpm in a Multitron Pro (Infors HT, Switzerland). The PET depolymerization rate was determined through regular sampling, and the samples were analyzed by ultra-high-performance liquid chromatography (UHPLC) to measure the amount of equivalent terephthalic acid produced according to the method described in Example 1. The percentage of hydrolysis of samples S2 to S6 and control-1 was calculated based on the total amount of equivalent TA (TA + MHET + BHET) at a given time versus the total amount of TA determined in the initial sample. The results for the percentage of depolymerization are shown in Table 6 below. QRfr / nn / zznz / e / Ywi Sample Percentage of depolymerization (%) at 28 h Control-1 6.0 S2 32.9 S3 46.5 S4 39.8 S5 20.5 S6 49.1 Table 6: Depolymerization rate of PET from a foamed plastic product comprising PET (S2 ​​to S6) compared to an unfoamed plastic product (control-1). The degradation process of a plastic product comprising PET previously foamed using a physical foaming agent (carbon dioxide or nitrogen) is improved 3 to 8 times compared to a plastic product that has not been foamed. Example 3 - Degradation process of a plastic product comprising PET that includes a foaming stage performed with a physical foaming agent and a cooling stage in a bath containing an enzymatic solution A) Supercritical CO2 foaming stage and subsequent cooling stage Washed and colored flakes of bottle waste comprising 98% PET were foamed with supercritical CO2 according to example 2-A. Two samples, S7 and S8, were prepared according to the detailed instructions in Table 7. The extrudate was immersed in water (S7) or in an enzyme bath containing water with approximately 4.3 g / l of the same recombinant LCC-ICCIG enzyme secreted as in Example 1 (S8). The resulting extrudates were rinsed with water, dried under ambient conditions, and then cut into 2–3 mm pieces using a blade mill. The experimental conditions used for sample preparation and the porosity and crystallinity results are shown in Table 7 below: Sample T4 (°C) T5 (°C) T6 (°C) Qp (g / min) QcO2 (ml / min) WCO2 (%) Cooling bath water Papp (kg / m3) (%) crystallinity (%) S7 250 250 250 11.43 0.3 2.4 water 582.3 57 16 S8 250 250 250 20 0.3 1.4 water + enzyme 627.9 42 16 Table 7: Experimental conditions used for the preparation of foamed plastic products and porosity and crystallinity results B) Dedolimerization Stage Depolymerization was performed on S7 and S8 in glass bottles as detailed in Example 2-B, except that S8 was tested without adding enzyme to the buffer. The depolymerization results are shown in Table 8. Sample Percentage of depolymerization (%) at 30h S7 75 S8 85 Table 8: Depolymerization rate of PET from a foamed plastic product comprising PET subjected to cutinase during the depolymerization step (S7), compared to a foamed plastic product comprising PET subjected to cutinase during the cooling step, without addition of cutinase during the depolymerization step (S8). The degradation process of a plastic product comprising PET that has been subjected to depolymerase during the cooling stage shows a slight increase in degradation compared to one that was brought into contact with the depolymerase only during the depolymerization stage. Example 4 - Degradation process of a plastic product comprising PLA that includes a foaming stage with a chemical foaming agent and a cooling stage in a bath containing an enzymatic solution A) Foaming stage with chemical foaming agent Poly(lactic acid) (PLA) 4043D (in granule form supplied by NatureWorks - 35% crystallinity) was foamed using a Leistritz ZSE 18 MAXX twin-screw extruder. This extruder comprises nine successive heating zones (Z1-Z9) and a die head (Z10) where the temperature can be independently controlled and regulated in each zone. A chemical foaming agent (CEA) color concentrate, HYDROCEROL BIH 40, supplied by Clariant, was used. PLA and CFA were dried in a desiccator for 14 h at 60 °C and 45 °C, respectively. 95 wt% PLA granules and 5 wt% CFA color concentrate were dry-mixed and added to the hopper of a gravimetric feeder for feeding into the extruder. A total flow rate of 2 kg / h was obtained. The temperature profile along the spindle is described in Table 9. The spindle speed rate was set to 100 rpm. QRfr;nn / zznz / e / Ywi Zon a Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z8 Z9 Z10 (cabezal) T °c 140 0 C 140 0 C 150 0 C 170 0 C 170 0 C 170 0 C 170 0 c 170 0 c 170 °C 165 °C Table 9: Temperature profile of the extruder used for the model called S9 The molten polymer reached the screw head (Z10), which comprised a die plate with a 3.5 mm orifice. The resulting extrudate was immediately immersed in a container with 1 L of commercially available Novozymes Savinase® 16L enzyme solution (known for its ability to degrade PLA) at 15 °C, then removed and manually wound. After 24 hours, the sample was washed with water and dried under ambient conditions (20 °C and 40% humidity) for 48 hours. The sample was then granulated using a rotary cutter into 2–3 mm solid granules (S9) with a crystallinity of 2%. As a control, another sample (S10) was also foamed in the same manner, except that the resulting extrudate was immersed in water without enzyme. S9 and S10 show a crystallinity of 2% and a porosity rate of 30% and 40% respectively. B) Depolymerization stage 100 mg of each alloy were weighed and placed into cellulose dialysis tubes. These tubes were then placed in a glass bottle containing 50 ml of 100 mM Tris buffer, pH 9.5, and incubated at 45 °C and 150 rpm. The percentage of alloy degradation was determined by UHPLC according to the following protocol. One-mL samples were taken regularly. After filtration through a 0.22 µm filter, the samples were loaded into a UHPLC system (Ultimate 3000 UHPLC system (Thermo Fisher Scientific, Inc., Waltham, MA, USA) including a pump module, autosampler, a column oven thermostated at 50 °C, and a UV detector at 210 nm) to monitor the release of lactic acid and lactic acid dimers. Lactic acid and lactic acid dimers were separated using an Aminex HPX-87H column and a 5 mM H₂SO₄ mobile phase at a flow rate of 0.5 mL min⁻¹. The injection volume was 20 µL of sample. Lactic acid (LA) and lactic acid dimers (DP2) were measured according to standard curves prepared from commercial lactic acid (Sigma-Aldrich L1750-10G) and lactic acid dimers synthesized internally under the same conditions as the samples. The degradation percentage was calculated according to the following molar ratio of LA plus the LA contained in DP2 at a given time versus the theoretical LA initially contained in the PLA. After 24 hours, S9 shows a degradation rate of 76%, while S10 shows no significant degradation. The results indicate that some enzymes became attached to the cellular structures of the foamed plastic material comprising PLA during the cooling phase. Example 5 - Degradation process of a textile product comprising PET that includes a foaming stage with a chemical foaming agent A) Foaming stage of a textile product comprising PET The textile waste (old clothes) made of PET was sorted, shredded, cleaned to remove its metals and hard contaminants (such as zippers or buttons) and compacted to obtain 2-4 mm sized textile granules containing 85% PET by weight. The same extruder, cooling and granulation equipment as in example 1 were used to prepare foamed granules from said PET textile granules. The compacted textile granules were fed into the main hopper (before Z1). Citric acid (Adeka Orgater exp 141 / 183) was used as the CFA and was fed into Z4 using a gravimetric feeder. The screw speed was set to 110 rpm. A total throughput of 4 kg / h was obtained, resulting in an extruded composition (S11) containing 1 wt% citric acid relative to the total weight of the composition. A control sample of the old clothes composition (control3) was extruded, cooled, and granulated without the use of a foaming agent. It was then micronized after immersion in liquid nitrogen to obtain a powder with a crystallinity level of 13%. The temperature profile established for extrusion is provided in Table 10. The screw speed was set to 200 rpm and the total flow rate to 4 kg / h. A woven textile material containing 100% PET was shredded and compacted, then dry-mixed with 1 wt% citric acid and 0.5 wt% water (based on the total weight of the mixture) prior to extrusion foaming. The same extruder used for sample S11 and control-3 was used. The dry mixture was fed into the main hopper (before Z1) via a gravimetric feeder. A total flow rate of 2.5 kg / h was achieved, resulting in an extruded composition (S12) containing 1 wt% citric acid. The screw speed was set to 150 rpm. The temperature profile along the spindle for samples S11, S12 and control-3 are shown in Table 10 below. QRfr / nn / zznz / e / YiAi Sample Zone Z1 Z2 Ζ3 Z4 Z5 Ζ6 Z7 Z8 Z9 Z10 (head) S11 TC 250 °C 250 °C 260 ”C 220 °C 230 °C 270 °C 270 °C 250 °C 230 O 230 °C S12 re 260 °C 260 °C 250 °C 250 °C 250 °C 250 °C 240 °C 240 °C 240 °C 240 °C Control3 T°C 265 °C 265 °C 265 'C 255 °C 255 °C 250 °C 250 °C 245 °C 245 °C 245 °C Table 10: Temperature profile of the extruder used for samples S11, S12 and control-3 S11 and S12 have a crystallinity level of 13% and 0% respectively and a porosity rate of 25% and 36% (with the actual density measured on an extruded but unfoamed textile composition). B) Depolymerization stage of the foamed textile product The depolymerization step was carried out under the same conditions as in example 1-B. The percentage of depolymerization obtained is summarized in Table 11 below. Sample Percentage of depolymerization (%) at 44h S11 89 S12 90 Control-3 85 Table 11: Depolymerization rate of PET from foamed textile products comprising PET (S11 and S12) compared to an extruded and micronized fabric without foaming (control-3). The results show that the process of the invention allows the micronization stage to be eliminated since the foamed textile product depolymerizes as much as the extruded and micronized textile composition without foaming (control-3). Example 6 - Degradation process of a plastic product comprising PET that includes a foaming stage performed with a chemical foaming agent and a depolymerization stage performed with a chemical depolymerizing agent A) Preparation of foamed plastic products In this example, the following materials were used: • Sample S1 BIS, which corresponds to the ground, washed, and colored flakes foamed with citric acid, as described in example 1-A)b) • Control-1 sample, which corresponds to the extruded and granulated flakes but without foaming (see example 1) • Control-2, which was obtained by micronizing the flakes of control-1 (see example 1) • Control-4, which corresponds to control-1 that has been subjected to an annealing treatment in a furnace at 120 °C for 48 hours to recrystallize the granules. Control-4 has a crystallinity level of approximately 32.2%. • Control-5 obtained by micronization of the granules of control-4 (using the methods described in example 1). B) Chemical depolymerization of foamed plastic products Chemical depolymerization was performed in 15 mL glass tubes (Supelco, 27162) with screw caps. A sample of approximately 40–50 mg of PET was placed in a glass tube, and a total of 800 mL of DCM and 400 mL of methanol / KOH (3 M) were added. The mixture was stirred for 5 minutes by magnetic stirring at room temperature (TA ~25 °C). The solvents were evaporated under a flow of N2 for 10 minutes. The PET monomers were dissolved in 14 mL of MilliQ water. The mixture was stirred for 5 minutes at TA. The amount of monoethylene glycol (MEG) produced was determined by ultra-high-performance liquid chromatography (UHPLC) according to the method described herein. The MEG concentration was determined by mixing 1.5 mL of sample with 0.5 mL of H₂SO₄. After homogenization and filtration through a 0.45 µm syringe filter, 20 µL of sample were injected into a UHPLC Ultimate 3000 system (Thermo Fisher Scientific, Waltham, MA) comprising a pump module, an autosampler, a column thermostated at 55 °C, and an R1 detector. MEG molecules were separated using an Aminex HPX-87H ion-exclusion HPLC column (300 mm x 7.8 mm, 9 µm) equipped with a pre-column (Supelco, Bellefonte, PA). MEG was eluted with 5 mM H₂SO₄ at a flow rate of 0.8 mL min⁻¹. MEG was measured using standard curves prepared from commercially available MEG. The reaction rate was ORfr;nn / zznz / e / YiAi was calculated based on the total amount of MEG at a given time versus the total amount of MEG determined in the initial sample. The reaction rate results are shown in Table 12 below, as well as the crystallinity level of each sample. Sample Description Sample Crystallinity Level (%) Reaction Rate in mg / min S1-BIS (from Example 1) Foamed Plastic Granule 1.0 9.6 Control-1 Extruded Plastic Granule, Unfoamed Granule 15.0 3.9 Control-2 Extruded Plastic Granule, Unfoamed Granule after Micronization 15.0 10 Control-4 Annealed Plastic Granule 32.2 0.3 Control-5 Annealed Plastic Granule after Micronization 31.8 7.9 Table 12: Chemical depolymerization rate of PET from the foamed plastic product comprising PET (S1-BIS) compared to the extruded and unfoamed product (control-1), the extruded and micronized product without foaming (control-2), the recrystallized granules (control-4), and the recrystallized and micronized product (control-5). The rate of the chemical reaction is expressed in mg / min. The results show that the foamed plastic product depolymerizes faster than the unfoamed plastic product and faster than the annealed (recrystallized) granule, with or without micronization. The results also show that the process of the invention allows for the elimination of the micronization step 15, since the foamed product depolymerizes as quickly as the extruded and micronized product without foaming.

Claims

1. A process for degrading a plastic product comprising at least one polymer, said process comprising the steps of: a. at least partially foaming the plastic product; and b. depolymerizing at least one target polymer from the at least partially foamed plastic product, wherein the foaming step is carried out at a temperature at which the plastic product is in a partially or totally molten state.

2. The process according to claim 1, wherein the foaming step is carried out at a temperature above the crystallization temperature (Te) of the target polymer, preferably at, or above, the melting temperature (Tm) of said polymer.

3. The process according to claim 1 or 2, wherein the foaming step is implemented with a physical foaming agent, preferably selected from gas, more preferably selected from the group consisting of nitrogen, carbon dioxide, methane, helium, neon, argon, xenon, hydrogen or a mixture thereof.

4. The process according to any one of the preceding claims, wherein the foaming step is implemented with a chemical foaming agent, preferably selected from the group consisting of citric acid, carbonate, bicarbonate or a mixture thereof, more preferably a mixture of citric acid and bicarbonate.

5. The process according to any one of the preceding claims, wherein the at least partially foamed plastic product has a porosity rate greater than 20%, preferably greater than 30%.

6. The process according to any one of the preceding claims, further comprising a cooling step of the at least partially foamed plastic product, less than 30 seconds after the foaming step, by subjecting the plastic product to a temperature below the crystallization temperature (Te) of the target polymer, preferably below the glass transition temperature (Tg) of said polymer.

7. The process according to claim 6, wherein said polymer has a crystallinity rate of at most 30%, preferably at most 25%, more preferably at most 20% after the cooling stage.

8. The process according to claim 6 or 7, wherein the at least partially foamed plastic product is subjected to a granulation stage between the cooling stage and the depolymerization stage.

9. The process according to any one of the preceding claims, wherein the foaming stage is carried out in an extruder.

10. The process according to any one of claims 1 to 8, wherein the foaming stage is carried out in an autoclave.

11. The process according to any one of the preceding claims, wherein the depolymerization step comprises contacting the plastic product with a depolymerizing agent, selected from a chemical and / or biological depolymerizing agent.

12. The process according to claims 1 to 10, wherein the plastic product is brought into contact with a depolymerizing agent prior to the depolymerization step, and wherein the depolymerization step is carried out by bringing the plastic product into contact with a liquid, preferably a liquid lacking a depolymerizing agent.

13. The process according to claim 11 or 12, wherein the depolymerizing agent is a biological depolymerizing agent, preferably a depolymerase. ORfr;nn / zznz / e / YiAi 14. The process according to claim 13, wherein the depolymerase is capable of degrading at least one polymer of the plastic product, preferably at least the target polymer of the plastic product.

15. The process according to any one of the preceding claims, wherein the foaming step is implemented with a chemical foaming agent and the depolymerizing agent is a depolymerase capable of degrading at least the target polymer of the plastic product.

16. The process according to any one of the preceding claims, further comprising a recovery step and optionally purification of oligomers and / or monomers resulting from the depolymerization step.

17. El proceso según una cualquiera de las reivindicaciones anterioris, en donde el producto plástico comprende al menos un poliéster, preferentemente seleccionado de poli(tereftalato de ethylene) (PET), poli(tereftalato de trimethylene) (PTT), poli(tereftalato de butileno) (PBT), poli(tereftalato de ethylene con ¡sosorbida) (PEIT), poli(ácido lactico) (PLA), polihidroxialcanoato (PHA), poli(succinato de butileno) (PBS), poli(succinato adipato de butileno) (PBSA), poli(adipato tereftalato de butileno) (PBAT), poli(furanoato de ethylene) (PEF), policaprolactone (PCL), poli(adipato de ethylene) (PEA), poly(butylene succinate terephthalate) (PBST), poly(ethylene succinate) (PES), poly(succinate / terephthalate / butylene isophthalate)co-(lactate) (PBSTIL) and combinations / mixtures of these materials, including the most preferentially selected poly(ethylene terephthalate) and poly(lactic acid).

18. A process for degrading a plastic product comprising at least PET comprising the steps of: a. at least partially foaming the plastic product with a chemical foaming agent, wherein the foaming step is carried out at a temperature above 170 °C, preferably 230 °C or higher, wherein the foaming agent is preferably selected from citrate, carbonate, bicarbonate and mixtures thereof; b. cooling said at least partially foamed plastic product to a temperature below 100 °C, preferably below 90 °C, preferably less than 30 seconds after the foaming step; c. depolymerizing PET from the cooled plastic product; and, optionally, recovering and optionally purifying oligomers and / or monomers resulting from the depolymerization of said PET.

19. The process of claim 18, wherein the depolymerization step is carried out by contacting the cooled plastic product with a biological depolymerizing agent, preferably a depolymerase.

20. The process according to claim 19, wherein the at least partially foamed plastic product is subjected to a granulation stage between the cooling stage and the depolymerization stage.

21. The process of claim 19 or 20, wherein the depolymerase is an esterase, preferably a cutinase or a lipase, more preferably a cutinase.

22. A method for producing monomers and / or oligomers and / or degradation products from a plastic product comprising at least one polymer, preferably PET, comprising successively subjecting the plastic product to a foaming step and a depolymerization step, preferably exposing the foamed plastic product to a depolymerase, preferably an esterase, more preferably a cutinase.

23. A process for degrading an at least partially foamed plastic product comprising at least one polymer, wherein the at least partially foamed plastic product is brought into contact with a depolymerizing agent capable of degrading at least one polymer of said plastic product and wherein said at least partially foamed plastic product is obtained from plastic waste and / or fiber waste that has been previously subjected to a foaming step.

24. The process of claim 23, wherein said polymer of said plastic product, at least partially foamed, has been previously depolymerized QRfr / nn / zznz / e / YiAi before coming into contact with the depolymerizing agent.

25. A process for recycling a selected plastic product from plastic waste and / or fiber waste comprising at least one polymer, 5 comprising the step of depolymerizing at least one target polymer from said plastic product, wherein the plastic product has been previously foamed at least partially.

26. The process of claim 25, wherein the polymer of said plastic product 10 has been previously amortized.

27. The process of claims 23 to 26, wherein the depolymerization step is carried out by subjecting the at least partially foamed plastic product to a biological depolymerizing agent, preferably a depolymerase, more preferably a depolymerase capable of degrading at least one polymer of the plastic product.