Methods of plastic pretreatment and depolymerization

Abstract

The disclosure relates to methods of increasing depolymerization capability of plastic, methods of preparing plastic particles for depolymerization, and methods of depolymerizing plastic.

Description

Attorney Docket No.129436-5005-WO METHODS OF PLASTIC PRETREATMENT AND DEPOLYMERIZATION BACKGROUND

[0001] Plastics are inexpensive and durable materials which can be used to manufacture a variety of products that find use in a wide range of applications; thus, the production of plastics has increased dramatically over the last decades. About 40% of these plastics are used for single- use disposable applications, such as packaging, agricultural films, disposable consumer items or for short-lived products that are discarded within a year of manufacture. Because of the durability of the polymers involved, substantial quantities of plastics are piling up in landfill sites and in natural habitats worldwide, generating increasing environmental problems. Even degradable and biodegradable plastics may persist for decades depending on local environmental factors, like levels of ultraviolet light exposure, temperature, presence of suitable microorganisms, etc.

[0002] One solution to reduce environmental and economic impacts correlated to the accumulation of plastic is closed-loop recycling wherein plastic material is mechanically reprocessed to manufacture new products. For example, one of the most common closed-loop recycling is the polyethylene terephthalate (PET) recycling. PET wastes are subjected to successive treatments leading to food-contact-approved recycled PET (rPET), which is collected, sorted, pressed into bales, crushed, washed, chopped into flakes, melted and extruded in pellets and offered for sale. Then, these recycled PET may be used to create fabrics for the clothing industry or new packaging such as bottles or blister packs, etc.

[0003] However, the actual plastic recycling processes use huge amounts of electricity, particularly during the extruding step, and the equipment used is also expensive, leading to high prices which may be non-competitive compared to virgin plastic.

[0004] Another potential process for recycling plastic includes chemical recycling allowing for the recovery of the chemical constituents of the polymer. The resulting monomers may then be used to remanufacture plastic or to make other synthetic chemicals. However, up to now, such recycling process has only been performed on purified polymers and is not efficient on raw plastic products having a mix of semi-crystalline and amorphous polymers and additives.Attorney Docket No.129436-5005-WO

[0005] Thus, a need exists for an improved process for recycling plastic products that does not require expensive pretreatments and that may be used for recycling different plastic materials. SUMMARY

[0006] The disclosure relates to methods of increasing depolymerization capability of plastic, methods of preparing plastic particles for depolymerization, and methods of depolymerizing plastic. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A shows % relative depolymerization of PET powder under different grinding speeds by G1P BHR cutinase.

[0008] Figure 1B shows % relative depolymerization of PET powder under different grinding speeds by G2P BHR cutinase.

[0009] Figure 2 shows particle size distribution under different grinding speeds.

[0010] Figure 3 shows % crystallinity of Kirkland water bottle flakes and ground powder.

[0011] Figure 4A shows % Relative Depolymerization of PET powder using cryoground process by G1P BHR cutinase.

[0012] Figure 4B shows % Relative Depolymerization of PET powder using cryoground process by G2P BHR cutinase.

[0013] Figure 5A shows % Relative Depolymerization of PET powder with preheating or increasing moisture content by G1P BHR cutinase.

[0014] Figure 5B shows % Relative Depolymerization of PET powder with preheating or increasing moisture content by G2P BHR cutinase. DETAILED DESCRIPTION

[0015] The present invention may be understood more readily by reference to the following detailed description of the preferred embodiments of the invention. However, although different components and methods are disclosed and described, it is to be understood that this invention is not limited to specific formulations, assemblies or configurations, conditions, or methods, as such may vary, and any modifications thereto and variations therein will be apparent to thoseAttorney Docket No.129436-5005-WO skilled in the art. It is also to be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0016] In one aspect, the disclosure provides a method of increasing depolymerization capability of plastic. In some embodiments, the method comprises decreasing crystallinity of the plastic and generating plastic particles. In some embodiments, the plastic particles comprise plastic powder particles.

[0017] In some embodiments, the methods disclosed herein decrease the crystallinity of the plastic. In some embodiments, the methods disclosed herein decrease the crystallinity of the plastic by at least about 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, or 95%. In some embodiments, the methods disclosed herein decrease the crystallinity of the plastic by at least about 40%. In some embodiments, the methods disclosed herein decrease the crystallinity of the plastic by at least about 60%. In some embodiments, the methods disclosed herein decrease the crystallinity of the plastic by at least about 65%.

[0018] In some embodiments, the methods disclosed herein decrease the crystallinity of the plastic by about 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 20% or less.

[0019] In some embodiments, the methods disclosed herein decrease the crystallinity of the plastic from about 1 to 95%, about 1 to 90%, about 1 to 85%, about 1 to 80%, about 1 to 75%, about 1 to 70%, about 1 to 65%, about 1 to 60%, about 1 to 55%, about 1 to 50%, about 1 to 45%, about 1 to 40%, about 1 to 35%, about 1 to 30%, about 1 to 25%, about 1 to 20%, from about 5 to 95%, about 5 to 90%, about 5 to 85%, about 5 to 80%, about 5 to 75%, about 5 to 70%, about 5 to 65%, about 5 to 60%, about 5 to 55%, about 5 to 50%, about 5 to 45%, about 5 to 40%, about 5 to 35%, about 5 to 30%, about 5 to 25%, about 5 to 20%, from about 10 to 95%, about 10 to 90%, about 10 to 85%, about 10 to 80%, about 10 to 75%, about 10 to 70%, about 10 to 65%, about 10 to 60%, about 10 to 55%, about 10 to 50%, about 10 to 45%, about 10 to 40%, about 10 to 35%, about 10 to 30%, about 10 to 25%, about 10 to 20%, from about 15 to 95%, about 15 to 90%, about 15 to 85%, about 15 to 80%, about 15 to 75%, about 15 to 70%, about 15 to 65%, about 15 to 60%, about 15 to 55%, about 15 to 50%, about 15 to 45%, about 15 to 40%, about 15 to 35%, about 15 to 30%, about 15 to 25%, about 15 to 20%, from about 20 to 95%, about 20 to 90%, about 20 to 85%, about 20 to 80%, about 20 to 75%, about 20 to 70%, about 20 to 65%, about 20 to 60%, about 20 to 55%, about 20 to 50%, about 20 to 45%, about 20 to 40%,Attorney Docket No.129436-5005-WO about 20 to 35%, about 20 to 30%, about 20 to 25%, from about 25 to 95%, about 25 to 90%, about 25 to 85%, about 25 to 80%, about 25 to 75%, about 25 to 70%, about 25 to 65%, about 25 to 60%, about 25 to 55%, about 25 to 50%, about 25 to 45%, about 25 to 40%, about 25 to 35%, about 25 to 30%, from about 30 to 95%, about 30 to 90%, about 30 to 85%, about 30 to 80%, about 30 to 75%, about 30 to 70%, about 30 to 65%, about 30 to 60%, about 30 to 55%, about 30 to 50%, about 30 to 45%, about 30 to 40%, about 30 to 35%, from about 35 to 95%, about 35 to 90%, about 35 to 85%, about 35 to 80%, about 35 to 75%, about 35 to 70%, about 35 to 65%, about 35 to 60%, about 35 to 55%, about 35 to 50%, about 35 to 45%, about 35 to 40%, from about 40 to 95%, about 40 to 90%, about 40 to 85%, about 40 to 80%, about 40 to 75%, about 40 to 70%, about 40 to 65%, about 40 to 60%, about 40 to 55%, about 40 to 50%, about 40 to 45%, from about 45 to 95%, about 45 to 90%, about 45 to 85%, about 45 to 80%, about 45 to 75%, about 45 to 70%, about 45 to 65%, about 45 to 60%, about 45 to 55%, about 45 to 50%, from about 50 to 95%, about 50 to 90%, about 50 to 85%, about 50 to 80%, about 50 to 75%, about 50 to 70%, about 50 to 65%, about 50 to 60%, about 50 to 55%, from about 55 to 95%, about 55 to 90%, about 55 to 85%, about 55 to 80%, about 55 to 75%, about 55 to 70%, about 55 to 65%, about 55 to 60%, from about 60 to 95%, about 60 to 90%, about 60 to 85%, about 60 to 80%, about 60 to 75%, about 60 to 70%, about 60 to 65%, from about 65 to 95%, about 65 to 90%, about 65 to 85%, about 65 to 80%, about 65 to 75%, about 65 to 70%, from about 70 to 95%, about 70 to 90%, about 70 to 85%, about 70 to 80%, about 70 to 75%, from about 75 to 95%, about 75 to 90%, about 75 to 85%, about 75 to 80%, from about 80 to 95%, about 80 to 90%, about 80 to 85%, from about 85 to 95%, about 85 to 90%, or from about 90 to 95%. In some embodiments, the methods disclosed herein decrease the crystallinity of the plastic from about 30 to 80%. In some embodiments, the methods disclosed herein decrease the crystallinity of the plastic from about 40 to 70%.

[0020] In one aspect, the disclosure provides a method of preparing plastic particles for depolymerization. In some embodiments, the method comprises grinding the plastic at a grinding speed configured to generate plastic particles having crystallinity of 20% or less. In some embodiments, the grinding speed is configured to generate plastic particles having crystallinity of 12% or less. In some embodiments, the grinding speed is configured to generate plastic particles having crystallinity of about 10% or less.Attorney Docket No.129436-5005-WO

[0021] In some embodiments, the grinding speed is configured to generate plastic particles having crystallinity of at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30%. In some embodiments, the grinding speed is configured to generate plastic particles having crystallinity of about 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10% or less.

[0022] In some embodiments, the grinding speed is configured to generate plastic particles having crystallinity from about 1 to 30%, from about 1 to 25%, from about 1 to 20%, from about 1 to 19%, from about 1 to 18%, from about 1 to 17%, from about 1 to 16%, from about 1 to 15%, from about 1 to 14%, from about 1 to 13%, from about 1 to 12%, from about 1 to 11%, from about 1 to 10%, from about 5 to 30%, from about 5 to 25%, from about 5 to 20%, from about 5 to 19%, from about 5 to 18%, from about 5 to 17%, from about 5 to 16%, from about 5 to 15%, from about 5 to 14%, from about 5 to 13%, from about 5 to 12%, from about 5 to 11%, from about 5 to 10%, from about 10 to 30%, from about 10 to 25%, from about 10 to 20%, from about 5 to 19%, from about 10 to 18%, from about 10 to 17%, from about 10 to 16%, from about 10 to 15%, from about 10 to 14%, from about 10 to 13%, from about 10 to 12%, from about 8 to 10%, from about 7 to 11%, from about 6 to 12%, from about 5 to 13%, from about 4 to 14%, from about 3 to 15%, or from about 2 to 16%.

[0023] In one aspect, the disclosure provides a method of increasing depolymerization capability of plastic. As used herein, the term “depolymerization capability” is understood by one of ordinary skill in the art. In some embodiments, term “depolymerization capability” refers to the ability recover the chemical constituents (i.e., monomers and / or oligomers) of the polymer. In some embodiments, the method comprises increasing a grinding speed to grind the plastic thereby generating plastic particles.

[0024] In some embodiments, the plastic is grinded at a grinding speed of about 6,000 RPM or higher, about 7,000 RPM or higher, about 8,000 RPM or higher, about 9,000 RPM or higher, about 10,000 RPM or higher, about 11,000 RPM or higher, about 12,000 RPM or higher, about 13,000 RPM or higher, about 14,000 RPM or higher, about 15,000 RPM or higher, about 16,000 RPM or higher, about 17,000 RPM or higher, about 18,000 RPM or higher, about 19,000 RPM or higher, about 20,000 RPM or higher, about 21,000 RPM or higher, about 22,000 RPM or higher, about 23,000 RPM or higher using RETSCH ZM200 Ultra Centrifugal Mill. In someAttorney Docket No.129436-5005-WO embodiments, the plastic is grinded at a grinding speed of about 6,000 RPM or higher using RETSCH ZM200 Ultra Centrifugal Mill. In some embodiments, the plastic is grinded at a grinding speed of about 12,000 RPM or higher using RETSCH ZM200 Ultra Centrifugal Mill. In some embodiments, the plastic is grinded at a grinding speed of about 18,000 RPM or higher using RETSCH ZM200 Ultra Centrifugal Mill.

[0025] In some embodiments, the plastic is grinded at a grinding speed of about 23,000 RPM or lower, about 22,000 RPM or lower, about 21,000 RPM or lower, about 20,000 RPM or lower, about 19,000 RPM or lower, about 18,000 RPM or lower, about 17,000 RPM or lower, about 16,000 RPM or lower, about 15,000 RPM or lower, about 14,000 RPM or lower, about 13,000 RPM or lower, about 12,000 RPM or lower, about 11,000 RPM or lower, about 10,000 RPM or lower using RETSCH ZM200 Ultra Centrifugal Mill.

[0026] In some embodiments, the plastic is grinded at a grinding speed from about 6,000 to 23,000 RPM, from about 7,000 to 23,000 RPM, from about 8,000 to 23,000 RPM, from about 9,000 to 23,000 RPM, from about 10,000 to 23,000 RPM, from about 11,000 to 23,000 RPM, from about 12,000 to 23,000 RPM, from about 13,000 to 23,000 RPM, from about 14,000 to 23,000 RPM, from about 15,000 to 23,000 RPM, from about 16,000 to 23,000 RPM, from about 17,000 to 23,000 RPM, from about 18,000 to 23,000 RPM, from about 19,000 to 23,000 RPM, from about 20,000 to 23,000 RPM, from about 21,000 to 23,000 RPM, from about 22,000 to 23,000 RPM, from about 6,000 to 22,000 RPM, from about 7,000 to 22,000 RPM, from about 8,000 to 22,000 RPM, from about 9,000 to 22,000 RPM, from about 10,000 to 22,000 RPM, from about 11,000 to 22,000 RPM, from about 12,000 to 22,000 RPM, from about 13,000 to 22,000 RPM, from about 14,000 to 22,000 RPM, from about 15,000 to 22,000 RPM, from about 16,000 to 22,000 RPM, from about 17,000 to 22,000 RPM, from about 18,000 to 22,000 RPM, from about 19,000 to 22,000 RPM, from about 20,000 to 22,000 RPM, from about 21,000 to 22,000 RPM, from about 6,000 to 21,000 RPM, from about 7,000 to 21,000 RPM, from about 8,000 to 21,000 RPM, from about 9,000 to 21,000 RPM, from about 10,000 to 21,000 RPM, from about 11,000 to 21,000 RPM, from about 12,000 to 21,000 RPM, from about 13,000 to 21,000 RPM, from about 14,000 to 21,000 RPM, from about 15,000 to 21,000 RPM, from about 16,000 to 21,000 RPM, from about 17,000 to 21,000 RPM, from about 18,000 to 21,000 RPM, from about 19,000 to 21,000 RPM, from about 20,000 to 21,000 RPM, from about 6,000 to 20,000 RPM, from about 7,000 to 20,000 RPM, from about 8,000 to 20,000 RPM, from aboutAttorney Docket No.129436-5005-WO 9,000 to 20,000 RPM, from about 10,000 to 20,000 RPM, from about 11,000 to 20,000 RPM, from about 12,000 to 20,000 RPM, from about 13,000 to 20,000 RPM, from about 14,000 to 20,000 RPM, from about 15,000 to 20,000 RPM, from about 16,000 to 20,000 RPM, from about 17,000 to 20,000 RPM, from about 18,000 to 20,000 RPM, from about 19,000 to 20,000 RPM, from about 6,000 to 19,000 RPM, from about 7,000 to 19,000 RPM, from about 8,000 to 19,000 RPM, from about 9,000 to 19,000 RPM, from about 10,000 to 19,000 RPM, from about 11,000 to 19,000 RPM, from about 12,000 to 19,000 RPM, from about 13,000 to 19,000 RPM, from about 14,000 to 19,000 RPM, from about 15,000 to 19,000 RPM, from about 16,000 to 19,000 RPM, from about 17,000 to 19,000 RPM, from about 18,000 to 19,000 RPM, from about 6,000 to 18,000 RPM, from about 7,000 to 18,000 RPM, from about 8,000 to 18,000 RPM, from about 9,000 to 18,000 RPM, from about 10,000 to 18,000 RPM, from about 11,000 to 18,000 RPM, from about 12,000 to 18,000 RPM, from about 13,000 to 18,000 RPM, from about 14,000 to 18,000 RPM, from about 15,000 to 18,000 RPM, from about 16,000 to 18,000 RPM, or from about 17,000 to 18,000 RPM using RETSCH ZM200 Ultra Centrifugal Mill. In some embodiments, the plastic is grinded at a grinding speed from about 6,000 to 18,000 RPM using RETSCH ZM200 Ultra Centrifugal Mill.

[0027] In some embodiments, the plastic comprises a polyester. In some embodiments, the polyester is a homopolymer or a copolymer. In some embodiments, the polyester comprises polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene isosorbide terephthalate (PEIT), polylactic acid (PLA), polyhydroxy alkanoate (PHA), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polyethylene furanoate (PEF), polycaprolactone (PCL), poly(ethylene adipate) (PEA), polybutylene succinate terephthalate (PBST), polyethylene succinate (PES), poly(butylene succinate / terephthalate / isophthalate)-co- (lactate) (PBSTIL), or blends and / or mixtures thereof. In some embodiments, the plastic comprises polyethylene terephthalate (PET).

[0028] In some embodiments, the plastic comprises plastic flakes. In some embodiments, the plastic is from a plastic article. In some embodiments, the plastic article is from plastic waste collection and / or post-industrial waste. In some embodiments, the plastic comprises a plastic bottle, a plastic tray, a plastic bag, plastic packaging, a soft and / or hard plastic, a fiber, a textile, a foamed plastic product, or mixtures thereof.Attorney Docket No.129436-5005-WO

[0029] In some embodiments, the plastic and / or plastic particles are amorphous, crystalline, or semi-crystalline. In some embodiments, the plastic and / or plastic particles are semi-crystalline. Crystallinity is measured by methods known to one of ordinary skill in the art. In some embodiments, crystallinity is measured by differential scanning calorimetry (DSC).

[0030] In some embodiments, the plastic has an initial crystallinity of at least about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, or 75%. In some embodiments, the plastic has an initial crystallinity of at least about 30%.

[0031] In some embodiments, the plastic has an initial crystallinity of about 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, or 20% or less.

[0032] In some embodiments, the plastic has an initial crystallinity from about 10 to 75%, from about 15 to 75%, from about 20 to 75%, from about 25 to 75%, from about 30 to 75%, from about 35 to 75%, from about 40 to 75%, from about 45 to 75%, from about 50 to 75%, from about 10 to 60%, from about 15 to 60%, from about 20 to 60%, from about 25 to 60%, from about 30 to 60%, from about 35 to 60%, from about 40 to 60%, from about 45 to 60%, from about 50 to 60%, from about 10 to 50%, from about 15 to 50%, from about 20 to 50%, from about 25 to 50%, from about 30 to 50%, from about 35 to 50%, from about 40 to 50%, from about 45 to 50%, from about 10 to 40%, from about 15 to 40%, from about 20 to 40%, from about 25 to 40%, from about 30 to 40%, from about 35 to 40%, from about 10 to 35%, from about 15 to 35%, from about 20 to 35%, from about 25 to 35%, from about 30 to 35%, from about 10 to 30%, from about 15 to 30%, from about 20 to 30%, or from about 25 to 30%.

[0033] In some embodiments, the plastic particles have crystallinity of at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30%.

[0034] In some embodiments, the plastic particles have crystallinity of about 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10% or less. In some embodiments, the plastic particles have crystallinity of about 20% or less. In some embodiments, the plastic particles have crystallinity of about 12% or less. In some embodiments, the plastic particles have crystallinity of about 10% or less.

[0035] In some embodiments, the plastic particles have crystallinity from about 1 to 30%, from about 1 to 25%, from about 1 to 20%, from about 1 to 19%, from about 1 to 18%, from about 1Attorney Docket No.129436-5005-WO to 17%, from about 1 to 16%, from about 1 to 15%, from about 1 to 14%, from about 1 to 13%, from about 1 to 12%, from about 1 to 11%, from about 1 to 10%, from about 5 to 30%, from about 5 to 25%, from about 5 to 20%, from about 5 to 19%, from about 5 to 18%, from about 5 to 17%, from about 5 to 16%, from about 5 to 15%, from about 5 to 14%, from about 5 to 13%, from about 5 to 12%, from about 5 to 11%, from about 5 to 10%, from about 10 to 30%, from about 10 to 25%, from about 10 to 20%, from about 5 to 19%, from about 10 to 18%, from about 10 to 17%, from about 10 to 16%, from about 10 to 15%, from about 10 to 14%, from about 10 to 13%, from about 10 to 12%, from about 8 to 10%, from about 7 to 11%, from about 6 to 12%, from about 5 to 13%, from about 4 to 14%, from about 3 to 15%, or from about 2 to 16%.

[0036] In some embodiments, the plastic particles have an average particle size of at least about 1, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, or 500 μm.

[0037] In some embodiments, the plastic particles have an average particle size of less than or equal to about 500, 490, 480, 470, 460, 450, 440, 430, 420, 410, 400, 390, 380, 370, 360, 350, 340, 330, 320, 310, 300, 290, 280, 270, 260, 250, 240, 230, 220, 210, 200, 190, 180, 170, 160, 150, 140, 130, 120, 110, 100, 90, 80, 70, 60, or 50 μm. In some embodiments, the plastic particles have an average particle size of less than or equal to about 500 μm. In some embodiments, the plastic particles have an average particle size of less than or equal to about 280 μm.

[0038] In some embodiments, the plastic particles have an average particle size from about 1 to 500 μm, from about 10 to 500 μm, from about 20 to 500 μm, from about 30 to 500 μm, from about 40 to 500 μm, from about 50 to 500 μm, from about 60 to 500 μm, from about 70 to 500 μm, from about 80 to 500 μm, from about 90 to 500 μm, from about 100 to 500 μm, from about 110 to 500 μm, from about 120 to 500 μm, from about 130 to 500 μm, from about 140 to 500 μm, from about 150 to 500 μm, from about 160 to 500 μm, from about 170 to 500 μm, from about 180 to 500 μm, from about 190 to 500 μm, from about 200 to 500 μm, from about 210 to 500 μm, from about 220 to 500 μm, from about 230 to 500 μm, from about 240 to 500 μm, from about 250 to 500 μm, from about 260 to 500 μm, from about 270 to 500 μm, from about 280 to 500 μm, from about 290 to 500 μm, from about 300 to 500 μm, from about 310 to 500 μm, fromAttorney Docket No.129436-5005-WO about 320 to 500 μm, from about 330 to 500 μm, from about 340 to 500 μm, from about 350 to 500 μm, from about 360 to 500 μm, from about 370 to 500 μm, from about 380 to 500 μm, from about 390 to 500 μm, from about 400 to 500 μm, from about 410 to 500 μm, from about 420 to 500 μm, from about 430 to 500 μm, from about 440 to 500 μm, from about 450 to 500 μm, from about 460 to 500 μm, from about 470 to 500 μm, from about 480 to 500 μm, from about 490 to 500 μm, from about 1 to 280 μm, from about 10 to 280 μm, from about 20 to 280 μm, from about 30 to 280 μm, from about 40 to 280 μm, from about 50 to 280 μm, from about 60 to 280 μm, from about 70 to 280 μm, from about 80 to 280 μm, from about 90 to 280 μm, from about 100 to 280 μm, from about 110 to 280 μm, from about 120 to 280 μm, from about 130 to 280 μm, from about 140 to 280 μm, from about 150 to 280 μm, from about 160 to 280 μm, from about 170 to 280 μm, from about 180 to 280 μm, from about 190 to 280 μm, from about 200 to 280 μm, from about 210 to 280 μm, from about 220 to 280 μm, from about 230 to 280 μm, from about 240 to 280 μm, from about 250 to 280 μm, from about 260 to 280 μm, from about 270 to 280 μm, from about 1 to 180 μm, from about 10 to 180 μm, from about 20 to 180 μm, from about 30 to 180 μm, from about 40 to 180 μm, from about 50 to 180 μm, from about 60 to 180 μm, from about 70 to 180 μm, from about 80 to 180 μm, from about 90 to 180 μm, from about 100 to 180 μm, from about 110 to 180 μm, from about 120 to 180 μm, from about 130 to 180 μm, from about 140 to 180 μm, from about 150 to 180 μm, from about 160 to 180 μm, or from about 170 to 180 μm. In some embodiments, the plastic particles have an average particle size from about 1 to 500 μm. In some embodiments, the plastic particles have an average particle size from about 280 to 500 μm. In some embodiments, the plastic particles have an average particle size from 180 to 280 μm.

[0039] In one aspect, the disclosure provides a method of depolymerizing plastic. In some embodiments, the method comprises preparing plastic particles as described herein. In some embodiments, the method comprises subjecting the plastic particles to an enzymatic degradation process.

[0040] In some embodiments, the enzymatic degradation process is catalyzed by a cutinase, a protease, a lipase, a carboxylesterase, an esterase, or mixtures thereof. In some embodiments, the enzymatic degradation process is catalyzed by a cutinase. A wild type Bhr-PETase, “G1P” (i.e. “Generation 1 Parent”), SEQ ID NO:1 herein, or “G2P” (i.e. “Generation 2 Parent”), which has amino acid substitution S27L in SEQ ID NO: 1 herein may be used to degrade the plasticAttorney Docket No.129436-5005-WO described herein. In some embodiments, the enzymatic degradation process is catalyzed by G1P BHR cutinase comprising SEQ ID NO: 1. In some embodiments, the enzymatic degradation process is catalyzed by G2P BHR cutinase. More details about the enzyme degradation is described in PCT / US2023 / 085214, which is incorporated by reference herein in its entirety. 1 snpyqrgpnp trsalttdgp fsvatysvsr lsvsgfgggv iyyptgttlt fggiamspgy 61 tadasslawl grrlashgfv vivintnsrl dfpdsrasql saalnylrts spsavrarld 121 anrlavaghs mgggatlris eqiptlkagv pltpwhtdkt fntpvpqliv gaeadtvapv 181 sqhaipfyqn lpsttpkvyv eldnathfap nspnaaisvy tiswmklwvd ndtryrqflc 241 nvndpalsdf rsnnrhcq (SEQ ID NO: 1)

[0041] In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of at least about 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100 % to SEQ ID NO: 1. In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of 80% or more to SEQ ID NO: 1. In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of 90% or more to SEQ ID NO: 1. In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising SEQ ID NO: 1.

[0042] In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of less than or equal to about 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100 % to SEQ ID NO: 1. In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of 100% or less to SEQ ID NO: 1.

[0043] In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity from about 50% to 100%, from about 55% to 100%, from about 60% to 100%, from about 65% to 100%, from about 70% to 100%, from about 75% to 100%, from about 80% to 100%, from about 85% to 100%, from about 90% to 100%, or from about 95% to 100% to SEQ ID NO: 1.Attorney Docket No.129436-5005-WO

[0044] In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of at least about 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100 % to SEQ ID NO: 2. In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of 80% or more to SEQ ID NO: 2. In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of 90% or more to SEQ ID NO: 2. In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising SEQ ID NO: 2.

[0045] In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of less than or equal to about 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100 % to SEQ ID NO: 2. In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of 100% or less to SEQ ID NO: 2.

[0046] In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity from about 50% to 100%, from about 55% to 100%, from about 60% to 100%, from about 65% to 100%, from about 70% to 100%, from about 75% to 100%, from about 80% to 100%, from about 85% to 100%, from about 90% to 100%, or from about 95% to 100% to SEQ ID NO: 2.

[0047] In some embodiments, the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of 80% or more to SEQ ID NO: 1 or SEQ ID NO: 2.

[0048] In some embodiments, the enzymatic degradation process is carried out in a buffer. In some embodiments, the buffer is at an acidic pH (i.e., pH<7). In some embodiments, the buffer is at a basic pH (i.e., pH>7). In some embodiments, the buffer is at a neutral pH (i.e., pH=7). In some embodiments, the buffer has a pH of at least about 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, or 14.0. InAttorney Docket No.129436-5005-WO some embodiments, the buffer is at a neutral pH (i.e., pH=7). In some embodiments, the buffer has a pH of less than or equal to about 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, or 14.0.

[0049] In some embodiments, the enzymatic degradation process is carried out in a buffer having a pH from about 1.0 to 14.0, from about 1.5 to 14.0, from about 2.0 to 14.0, from about 2.5 to 14.0, from about 3.0 to 14.0, from about 3.5 to 14.0, from about 4.0 to 14.0, from about 4.5 to 14.0, from about 5.0 to 14.0, from about 5.5 to 14.0, from about 6.0 to 14.0, from about 6.5 to 14.0, from about 7.0 to 14.0, from about 7.5 to 14.0, from about 8.0 to 14.0, from about 8.5 to 14.0, from about 9.0 to 14.0, from about 9.5 to 14.0, from about 10.0 to 14.0, from about 10.5 to 14.0, from about 11.0 to 14.0, from about 11.5 to 14.0, from about 12.0 to 14.0, from about 12.5 to 14.0, from about 13.0 to 14.0, from about 1.0 to 12.0, from about 1.5 to 12.0, from about 2.0 to 12.0, from about 2.5 to 12.0, from about 3.0 to 12.0, from about 3.5 to 12.0, from about 4.0 to 12.0, from about 4.5 to 12.0, from about 5.0 to 12.0, from about 5.5 to 12.0, from about 6.0 to 12.0, from about 6.5 to 12.0, from about 7.0 to 12.0, from about 7.5 to 12.0, from about 8.0 to 12.0, from about 8.5 to 12.0, from about 9.0 to 12.0, from about 9.5 to 12.0, from about 10.0 to 12.0, from about 10.5 to 12.0, from about 11.0 to 12.0, from about 1.0 to 10.0, from about 1.5 to 10.0, from about 2.0 to 10.0, from about 2.5 to 10.0, from about 3.0 to 10.0, from about 3.5 to 10.0, from about 4.0 to 10.0, from about 4.5 to 10.0, from about 5.0 to 10.0, from about 5.5 to 10.0, from about 6.0 to 10.0, from about 6.5 to 10.0, from about 7.0 to 10.0, from about 7.5 to 10.0, from about 8.0 to 10.0, from about 8.5 to 10.0, from about 9.0 to 10.0, from about 1.0 to 9.0, from about 1.5 to 9.0, from about 2.0 to 9.0, from about 2.5 to 10.0, from about 3.0 to 9.0, from about 3.5 to 9.0, from about 4.0 to 9.0, from about 4.5 to 9.0, from about 5.0 to 9.0, from about 5.5 to 9.0, from about 6.0 to 9.0, from about 6.5 to 9.0, from about 7.0 to 9.0, from about 7.5 to 9.0, or from about 8.0 to 9.0. In some embodiments, the enzymatic degradation process is carried out in a buffer having a pH from about 6.5 to 10.0.

[0050] In some embodiments, the methods disclosed herein comprise removing plastic particles larger than about 100, 150, 180, 200, 250, 280, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, or 1,000 m prior to the subjecting. In some embodiments, the methods disclosed herein comprise removing plastic particles larger than about 500 m prior to the subjecting.Attorney Docket No.129436-5005-WO

[0051] In some embodiments, the methods disclosed herein exclude increasing moisture content of the plastic particles. In some embodiments, the methods disclosed herein exclude preheating the plastic particles. EXAMPLES Example 1: Pretreatment process and enzymatic degradation of a plastic product containing PET

[0052] A Kirkland (“KKL”) Signature purified water bottle containing PET was collected after use. After removing its cap and label, the main body of the water bottle was cut into 3x6 mm flakes and then ground into powder form using RETSCH ZM200 Ultra Centrifugal Mill equipped with a 500 μm distance sieve with speed ranging from 6,000 rpm to 18,000 rpm at room temperature to increase the surface of contact between PET product and enzyme. Each grinding cycle was set at 15-25 seconds to avoid overheating. The PET powder after grinding was collected and sieved using RETSCH AS 200 Control 8" Sieve Shaker for 3 min. After sieving, only the PET powder fraction with size lower than 500 μm was used for enzymatic degradation process.

[0053] 0.8 gram of PET powder was added into a 100 mL glass bottle with cap with 20 mL of Tris-HCl buffer (0.4 M, pH 9.0). The enzymatic degradation process was initiated by adding G1P or G2P BHR cutinase with final concentration of 40 mg / L (Protein titer was determined by Bradford protein assay using Bio-Rad Quick StartTMBradford Protein Assay Kit and then incubating at 65oC at 500 rpm in Incubation shaker (Infors HT Multitron Incubation shaker).

[0054] At 6- and 23-hours reaction time, 0.8 mL of reaction solution was sampled and diluted using 0.1 M Phosphate buffer when required. After filtered through 0.45 μm 96-well filter plate with centrifuge at 4000 rpm, samples were analyzed by HPLC to monitor the production of BHET, MHET and terephthalic acid (TPA). The concentration of BHET, MHET and TPA were calculated according to the standard curves prepared by commercial BHET, MHET and TPA products.

[0055] The percentage of depolymerization (% Depolymerization) of Kirkland Signature purified water bottle powder samples under different grinding speed were calculated based on ratio of released TPA equivalent (BHET+MHET+TPA) molar concentration at given time versus the total molar concentration of TPA contained in the initial powder samples added. TheAttorney Docket No.129436-5005-WO percentage of relative depolymerization (% Relative Depolymerization) of each Kirkland Signature purified water bottle powder sample was calculated based on the ratio of % Depolymerization at different grinding speed versus the % Depolymerization of powder sample ground at 12,000 rpm at given time. Results of % Relative Depolymerization are shown in Figures 1A-1B and Table 1. Table 1: % Relative Depolymerization of PET powder ground at different speed in room temperature by G1P and G2P BHR cutinase

[0056] For both G1P and G2P BHR cutinase used for enzymatic degradation, the % Relative Depolymerization was increased with the increase of grinding speed for PET powder preparation at both 6- and 23-hours reaction time. Compared to PET powder ground at low speed of 6,000 rpm, the initial depolymerization rate at 6 hours reaction was improved by ~3-5 times using PET powder sample ground at middle level speed of 12,000 rpm, and further improved to ~4.5-7 times using PET powder samples ground at high level speed of 18,000 rpm.Attorney Docket No.129436-5005-WO

[0057] PET powder particle size distribution was determined by sieving 10 grams of < 500 μm ground PET powder through 280 μm and 180 μm sieves using RETSCH AS 200 Control 8" Sieve Shaker for 3 min. After sieving, each powder fraction at 280-500 μm, 180-280 μm and < 180 μm were collected and weighed. The % particle size distribution of each powder fraction was calculated based on the weight of each fraction versus the total weight of initial < 500 μm PET powder added for sieving. Results of % Particle size distribution of PET powder generated at 6,000 rpm, 12,000 rpm and 18,000 rpm grinding speed are shown in Figure 2 and Table 2. Table 2: % Particle size distribution at different grinding speed – Summary.

[0058] The % particle size distribution for PET powder ground at 6,000 rpm is similar to the powder ground at 12,000 rpm with ~70-74% of powder size at 280-500 μm and ~26-30% of powder size at <280 nm. With the increase of grinding speed to 18,000 rpm, its % particle size distribution at 280-500 μm was significantly reduced to ~39-43% and the smaller % particle size distribution at <280 nm increased to 57-61%.

[0059] The crystallinity of Kirkland Signature purified water bottle PET flakes (before grinding) and < 500 μm powder ground at 6,000 rpm, 12,000 rpm and 18,000 rpm were determined by differential scanning calorimetry (DSC) using a Q2000 DSC (TA Instruments) on 5-10 mg of PET samples placed in hermetically sealed aluminum pans. The samples were analyzed from 0 to 300oC at a rate of 10oC per min. The measured % crystallinity of Kirkland signature purified water bottle PET flakes and < 500 μm powder ground at different grinding speed are shown in Figure 3 and Table 3. Table 3: % Crystallinity of Kirkland water bottle flakes and ground powder.Attorney Docket No.129436-5005-WO Kirkland water bottle ground powder 18000 <500 9.1

[0060] The % crystallinity of bottle flakes before grinding was 16.7%. With the increase of the grinding speed, the % crystallinity of ground powder decreased significantly and reached to 17.5%, 11.9 and 9.1% at grinding speed of 6,000 rpm, 12,000 rpm and 18,000 rpm, respectively. Example 2: Enzymatic degradation of a plastic product containing PET pretreated by cryoground process

[0061] A Kirkland Signature purified water bottle containing PET was collected after use. After removing its cap and label, the main body of the water bottle was cut into 3x6 mm flakes and immersed in liquid nitrogen for 2 min, and then ground into powder form using RETSCH ZM200 Ultra Centrifugal Mill equipped with a 500 μm distance sieve with speed ranging at 6,000 rpm, 12,000 rpm and 18,000 rpm. Each grinding cycle was set at 15-25 seconds to avoid overheating. The PET powder after grinding was collected and sieved using RETSCH AS 200 Control 8" Sieve Shaker for 10 min. After sieving, only the PET powder fraction with size lower than 500 μm was used for enzymatic degradation process.

[0062] The enzymatic degradation process on PET powder material with or without liquid nitrogen pretreatment before grinding by G1P and G2P BHR cutinase was conducted in glass bottles using the same material and methods as described in Example 1.

[0063] The % Depolymerization of each Kirkland signature purified water bottle powder samples with or without liquid nitrogen treatment at 6 and 23-hours reaction time was calculated based on the released BHET, MHET and TPA products as previously described in Example 1. The % Relative Depolymerization of each powder sample was calculated based on the ratio of % Depolymerization at different grinding speed with or without liquid nitrogen treatment versus the % Depolymerization of powder samples ground at 12,000 rpm without liquid nitrogen treatment at given time. Results of % Relative Depolymerization are shown in Figures 4A-4B and Tables 4-5. Table 4: % Relative Depolymerization of PET powder using cryoground process by G1P BHR cutinase.Attorney Docket No.129436-5005-WOTable 5: % Relative Depolymerization of PET powder using cryoground process by G2P BHR cutinase.

[0064] For both G1P and G2P BHR cutinase used for enzymatic degradation, at each grinding speed of 6,000 rpm, 12,000 rpm and 18,000 rpm, the % Relative Depolymerization was reduced using the cryoground PET powder with liquid nitrogen treatment compared to PET powder ground at room temperature without liquid nitrogen treatment. For the PET powder ground at 6,000 rpm with liquid nitrogen (Cryoground process), its % Relative Depolymerization at 6 hours and 23 hours reaction decreased by 30-50% compared to the PET powder ground at room temperature using same speed. For the PET powder ground at 12,000 rpm and 18,000 rpm with liquid nitrogen (Cryoground process), its % Relative Depolymerization at 6 hours and 23 hours reaction decreased by 10-30% compared to the PET powder ground at room temperature using same speed. The combination of liquid nitrogen treatment and low grinding speed showed the lowest % Depolymerization for PET powder. Example 3: Effect of pre-heating process and moisture content in PET powder grinding process on enzymatic degradation of a plastic product containing PET

[0065] A Kirkland Signature purified water bottle containing PET was collected after use. After removing its cap and label, the main body of the water bottle was cut into 3x6 mm flakes. TheAttorney Docket No.129436-5005-WO flakes were either pre-heated in oven at 80oC (above its glass transition temperature Tg) in oven for 1.5 hours to grind after heating immediately or added 5% water (w / w) to increase moisture content during grinding process. The pretreated flakes were then ground into powder form using RETSCH ZM200 Ultra Centrifugal Mill equipped with a 500 μm distance sieve with speed ranging at 12,000 rpm. Each grinding cycle was set at 15-25 seconds to avoid overheating. The PET powder after grinding was collected and sieved using RETSCH AS 200 Control 8" Sieve Shaker for 10 min. After sieving, only the PET powder fraction with size lower than 500 μm was used for enzymatic degradation process.

[0066] The enzymatic degradation process on PET powder material with or without preheating or the increase of moisture content before grinding by G1P and G2P BHR cutinase was conducted in glass bottles using the same material and methods as described in Example 1.

[0067] The % Depolymerization of each Kirkland signature purified water bottle powder samples with or without preheating or the increase of moisture content before grinding at 6 and 23-hours reaction time was calculated based on the released BHET, MHET and TPA products as previously described in Example 1. The % Relative Depolymerization of each powder sample was calculated based on the ratio of % Depolymerization of each PET powder sample versus the % Depolymerization of powder sample ground at 12,000 rpm without preheating and the increase of moisture content at given time. Results of % Relative Depolymerization are shown in Figures 5A-5B and Tables 6-7. Table 6: % Relative Depolymerization of PET powder with preheating or increasing moisture content by G1P BHR cutinase.Table 7: % Relative Depolymerization of PET powder with preheating or increasing moisture content by G2P BHR cutinase.Attorney Docket No.129436-5005-WO

[0068] For both G1P and G2P BHR cutinase used for enzymatic degradation, the preheating process of PET flakes before grinding did not significantly affect the % Relative Depolymerization with less than 5% reduction compared to PET powder generated without preheating process. Increasing moisture content by adding 5% water in the flakes led to slightly lower % Relative Depolymerization (5-10% lower) compared to PET powder generated without adding water.

Claims

Attorney Docket No.129436-5005-WO CLAIMS 1. A method of increasing depolymerization capability of plastic, the method comprising: decreasing crystallinity of the plastic and generating plastic particles.

2. The method according to claim 1, wherein the crystallinity of the plastic particles is decreased by at least about 40%.

3. A method of preparing plastic particles for depolymerization, the method comprising: grinding the plastic at a grinding speed configured to generate plastic particles having crystallinity of 20% or less.

4. The method according to claim 3, wherein the grinding speed is configured to generate plastic particles having crystallinity of 12% or less.

5. A method of increasing depolymerization capability of plastic, the method comprising: increasing a grinding speed to grind the plastic thereby generating plastic particles.

6. The method according to any one of claims 3-5, wherein the plastic is grinded at a grinding speed of 6,000 RPM or higher using RETSCH ZM200 Ultra Centrifugal Mill.

7. The method according to any one of claims 3-6, wherein the plastic is grinded at a grinding speed of 12,000 RPM or higher using RETSCH ZM200 Ultra Centrifugal Mill.

8. The method according to any one of claims 3-7, wherein the plastic is grinded at a grinding speed of 18,000 RPM or higher using RETSCH ZM200 Ultra Centrifugal Mill.

9. The method according to any one of the preceding claims, wherein the plastic comprises polyethylene terephthalate.

10. The method according to any one of the preceding claims, wherein the plastic particles have crystallinity of 20% or less.

11. The method according to any one of the preceding claims, wherein the plastic particles have crystallinity of 12% or less.

12. The method according to any one of the preceding claims, wherein the plastic particles have crystallinity of 10% or less.Attorney Docket No.129436-5005-WO 13. The method according to any one of the preceding claims, wherein the plastic particles have an average particle size of less than or equal to 500 μm.

14. The method according to any one of the preceding claims, wherein the plastic particles have an average particle size of less than or equal to 280 μm.

15. The method according to any one of the preceding claims, wherein the plastic particles have an average particle size from 280 to 500 μm.

16. The method according to any one of the preceding claims, wherein the plastic particles have an average particle size from 180 to 280 μm.

17. A method of depolymerizing plastic, the method comprising: preparing plastic particles according to a method of any one of the preceding claims, and subjecting the plastic particles to an enzymatic degradation process.

18. The method according to claim 17, wherein the enzymatic degradation process is catalyzed by a protein comprising an amino acid sequence having a sequence identity of 80% or more to SEQ ID NO: 1 or SEQ ID NO:

2.

19. The method according to claim 17 or 18, wherein the enzymatic degradation process is carried out in a buffer having a pH from 6.5 to 10.

0.

20. The method according to any one of claims 17-19, further comprising removing plastic particles larger than 500 m prior to the subjecting.

21. The method according to any one of claims 17-20, excluding increasing moisture content of the plastic particles.

22. The method according to any one of claims 17-21, excluding preheating the plastic particles.

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