Polymer for use in recycling plastic and as compatibilizer

Abstract

A polymer selected from the group consisting of Formula 1, Formula 2, and Formula 3 is described. An example of the polymer is Formula 4. The polymer contains a polyolefin backbone and is grafted with a polar functional group that is attached to an epoxy containing component. The polymer may be used in recycling plastic and as a compatibilizer.

Description

TITLE OF THE INVENTION: POLYMER FOR USE IN RECYCLING PLASTIC AND AS COMPATIBILIZERREFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to Singapore patent application number 10202400211V with a filing date of 25 January 2024 and titled “A New Chain Extender for Polyolefin Recycling”FIELD OF THE INVENTION

[0002] The present application relates to a polymer. The polymer may be used in recycling plastic and as a compatibilizer.BACKGROUND OF THE INVENTION

[0003] It is an undeniable fact that the need for sustainable materials is crucial to dimmish the negative effects associated with the disposal of plastics. The development of new polymer blends and composites using plastic waste streams is of great economic importance for the recycling industries and is also significantly beneficial for global environmental health. The recycling of post-consumer plastics is complicated by factors such as polymer degradation and incompatibility between different polymers which result in phase separation and low-quality materials with inferior mechanical properties. The urgent need to enhance recycling abilities of high-volume nondegradable plastics such as polyolefins has driven the development of additives called “chain extenders” to bring back the original or even better performance of the plastics. Chain extension with designed multifunctional polymers is typically introduced to enhance the properties of polymers, enabling them to be reused in the same and / or higher value applications. With a suitable design of functional polymer, the chain extender may also be able to compatibilize different polymers.SUMMARY OF THE INVENTION

[0004] In a first aspect, there is provided a polymer selected from the group consisting of Formula 1 , Formula 2, and Formula 3.

[0005] In Formula 1 , 2 and 3, x is from 50 to 5000, y1is from 5 to 500, y2 is from 0 to 100, y1+ y2is from 5 to 500, R1is CH3 or H. R2is a trivalent hydrocarbon having 2 to 20 carbon atoms which is optionally substituted with one or more heteroatoms or functional groups. R3is a divalent hydrocarbon having 2 to 20 carbon atoms which is optionally substituted with one or more heteroatoms or functional groups. R4is a monovalent hydrocarbon having 1 to 20 carbon atoms which is optionally substituted with one or more heteroatoms or functional groups. Z1and Z2(if present) is each independently selected from the group consisting of, R5, R6, R7, and R8are each independently a divalent hydrocarbon having 2 to 20 carbon atoms which is optionally substituted, ai is from 5 to 500. Z1and Z2are epoxide containing moieties that may react with other functional groups for the polymer to be used. In an embodiment, the value of y1is 1 to 10% of the value of x which may represent the amount of grafting on the polyolefin backbone. The monomer containing the carboxylic acid may not react completely with the Z1or Z2moieties, and the amount may be controlled by the molar ratio of the reagents used. The polymer of Formula 1 , Formula 2 and Formula 3 is a graft polymer. The grafted monomer in the polymer backbone may be in any order as per a graft polymer. The grafted monomer may be in random sequence or in a repeating sequence, for example repeating sequence or a block type polymer, or combinations thereof.

[0006] In an embodiment, the polymer is of Formula 1 ,Formula 1 . In Z1, R5, R6, R7, and R8are each independently having 2 to 6 carbon atoms and each independently selected from the group consisting of a divalent substituted alkyl moiety or a divalent unsubstituted alkyl moiety, in Z2R5, R6, R7, and R8are each independently having 6 to 20 carbon atoms and each independently selected from the group consisting of a divalent substituted aralkyl moiety, a divalent unsubstituted aralkyl moiety, a divalent substituted aryl moiety, and a divalent unsubstituted aryl moiety.

[0007] Preferably, Z1More preferablyR6and R7are each a divalent unsubstituted alkyl moiety with 2 to 6 carbon atoms or a divalent substituted alkyl moiety with 2 to 6 carbon atoms. In an embodiment, R6is -CH2CH(OH)CH2- and R7is the divalent unsubstituted alkyl moiety with 2 to 6 carbon atoms.

[0008] Preferably,the divalent substituted or unsubstituted aralkyl moiety of R8is selected from the group consisting of a divalent bisphenol moiety, a divalent phenol novolak moiety, and a divalent cresol novolak moiety. More preferably, the divalent bisphenol moiety is selected from the group consisting of bisphenol A, bisphenol S, and bisphenol F.

[0009] In an embodiment, the polymer is of Formula 2,Formula 2, wherein in Z1, R5, R6, R7, andR8are each independently selected from the group consisting of a divalent substituted alkyl moiety having 2 to 6 carbon atoms, a divalent unsubstituted alkyl moiety having 2 to 6 carbon atoms, a divalent substituted aralkyl moiety having 6 to 20 carbon atoms, a divalent unsubstituted aralkyl moiety having 6 to 20 carbon atoms, a divalent substituted aryl moiety having 6 to 20 carbon atoms, and a divalent unsubstituted aryl moiety having 6 to 20 carbon atoms.

[0010] Preferably, R2and R3where applicable is a divalent alkyl moiety having 2 to 10 carbon atoms optionally substituted with one or more heteroatoms orfunctional groups, preferably the divalent alkyl moiety having 2 to 6 carbon atoms optionally substituted with one or more heteroatoms or functional groups. In an embodiment, R2is a divalent alkyl moiety having 2 carbon atoms.

[0011] In an embodiment, the polymer is of Formula 3,Formula 3, R4is methyl or ethyl, wherein in Z1, R5, R6, R7, and R8are each independently selected from the group consisting of a divalent substituted alkyl moiety having 2 to 6 carbon atoms, a divalent unsubstituted alkyl moiety having 2 to 6 carbon atoms, a divalent substituted aralkyl moiety having 6 to 20 carbon atoms, a divalent unsubstituted aralkyl moiety having 6 to 20 carbon atoms, a divalent substituted aryl moiety having 6 to 20 carbon atoms, and a divalent unsubstituted aryl moiety having 6 to 20 carbon atoms.

[0012] Preferably, R1is CH3 ory2 is 0. When y2 is 0, all the grafted polar functional groups are attached to the epoxy containing component.

[0013] In an embodiment, y1and ai is each independently selected from 5 to 200, preferably y1and ai is each independently selected from 5 to 100, more preferably y1and ai is each independently selected from 5 to 50.

[0014] In an embodiment, the polymer is of Formula 4,x is from 50 to 5000, y, m, and n is each independently selected from 5 to 500. In an embodiment, y, m and n is each independently selected from 5 to 200, preferably y, m and n is each independently selected from 5 to 100, more preferably y, m and n is each independently selected from 5 to 50.

[0015] In an embodiment, x is from 50 to 4000, preferably x is from 50 to 3000, more preferably x is from 50 to 1000, even more preferably x is from 50 to 500.

[0016] In a second aspect, there is provided a polymer blend comprising the polymer according to the first aspect and a second polymer.

[0017] In an embodiment, the polymer is present in 0.1 to 50 wt.% of the polymer blend. Preferably, the polymer is present in 1 to 10 wt.% of the polymer blend. More preferably, the polymer is present in 1 to 5 wt.% of the polymer blend.

[0018] Preferably, the second polymer is a used polymer, and the polymer reacts with the used polymer. The used polymer may be degraded polymer and may be both from post-industrial or post-consumer use. Advantageously, the polymer repairs the used polymer and restores its properties to or near the original polymer’s properties.

[0019] Preferably, the used polymer has the same polymer backbone in the polymer of Formulas 1 to 4. For example, if the used polymer is a used polyolefin, the polymer may be of Formula 1 or Formula 2, and specifically if the used polymer is polypropylene, the polymer may also be of Formula 4. If the used polymer is polyethylene, the polymer may be similar to Formula 4 but the polymer backbone is polyethylene rather than polypropylene. If the used polymer is a polyacrylate, thepolymer may be of Formula 3. Preferably, the polymer blend further comprises maleic anhydride grafted polyolefin and / or glass fibres. Examples of the maleic anhydride grafted polyolefin include maleic anhydride grafted polypropylene (MAPP) and maleic anhydride grafted polyethylene. The maleic anhydride grafted polyolefin used is preferably the same as the polyolefin to be recycled.

[0020] In an embodiment, the polymer blend further comprises a third polymer which is different from the second polymer. Advantageously, this allows the polymer of the first aspect to function as a compatibilizer and allows the second polymer and third polymer to form a miscible blend that may be more stable and with different properties.

[0021] In a third aspect there is provided a method of producing a polymer blend. The method comprises mixing the polymer according to the first aspect and a second polymer to produce the polymer blend, wherein the mixing step is a molten stage mixing process and is by extrusion or batch mixing.

[0022] Preferably the method further comprises mixing maleic anhydride grafted polyolefin and / or glass fibres. Examples of the maleic anhydride grafted polyolefin include maleic anhydride grafted polypropylene (MAPP) and maleic anhydride grafted polyethylene.

[0023] In a fourth aspect, the polymer of Formula 1 , Formula 2, Formula 3 and Formula 4 may be used to recycle a used polymer like used polyolefin (for example used polypropylene and used polyethylene) and used polyacrylates. A method of recycling a used polymer, the method comprises mixing the used polymer with the polymer selected from the group consisting of Formula 1 , Formula 2, Formula 3 and Formula 4, wherein the mixing step is a molten stage mixing process and is by extrusion or batch mixing.

[0024] In a fifth aspect, the polymer of Formula 1 , Formula 2, Formula 3 and Formula 4 may be used as a compatibilizing agent (or compatibilizer). A method may comprise mixing the polymer selected from the group consisting of Formula 1 , Formula 2, Formula 3 and Formula 4, a second polymer and a third polymer, the second polymer and the third polymer are different polymers, to form a polymer blend. The second polymer and the third polymer may be immiscible by their ownbut the addition of the polymer of Formula 1 , Formula 2, Formula 3 and Formula 4 as a compatibilizing agent allows a miscible polymer blend to be formed which may be used.

[0025] Advantageously, the polymer of Formula 1 , Formula 2, Formula 3 and Formula 4 provides a more cost-effective solution to recycle used polymers (plastics) and contributes to reducing the amount of waste generated and the consumption of new raw materials. The polymer of Formula 1 , Formula 2 and Formula 3 is cheaper per kilogram and easier to use to recycle plastic waste than existing similar polymers.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure (FIG.) 1 shows the structures of the chain extenders used in the examples.

[0027] FIG. 2 shows a generic example of an embodiment of the invention.

[0028] FIG. 3 shows a specific example of an embodiment of the invention.

[0029] FIG. 4 shows the repair of a degraded polymer by an embodiment of the invention.

[0030] FIG. 5 shows the mechanical performance of PP(PCR) after addition of chain extender. FIG. 5A and FIG. 5B shows the flexural strength and tensile strength of the plastic compositions prepared.

[0031] FIG. 6 shows the mechanical properties of PP(PCR) / GF composites. FIG. 6A and FIG. 6B shows the flexural strength and tensile strength of the plastic compositions with glass fibres prepared.

[0032] FIG. 7 shows the SEM images of PP(PCR) / GF and PP(PCR) / GF / Linker. FIG. 7A and FIG. 7B are the images without the Linker and with the Linker respectively.DETAILED DESCRIPTION OF THE INVENTION

[0033] In the following description, numerous specific details are set forth in order to provide a thorough understanding of various illustrative embodiments of the invention. It will be understood, however, to one skilled in the art, that embodimentsof the invention may be practiced without some or all of these specific details. Embodiments described in the context of one of the methods or devices are analogously valid for the other methods or devices. Similarly, embodiments described in the context of a method are analogously valid for a device, and vice versa.

[0034] Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which this invention belongs.

[0035] The phrase “at least one of A and B” means it requires only A alone, B alone, or A and B, i.e. only one of A or B is required.

[0036] The term “aryl group” refers to a moiety which includes carbocyclic aromatic rings and heteroaryl rings (nitrogen, oxygen, and sulphur and the like), and in particular refers to the atom forming the bond being part of the ring structure. The term “aromatic group” may be used interchangeably with the terms “aryl”, “aryl ring” “aromatic ring”, “aryl group” and “aromatic group”. The aryl group may be substituted at any one or more substitutable ring atom. Non-limiting examples of substituents include a halogen, a hydroxyl, an ether, an amine, a carbamate, a carbonate ester, a urea, an aliphatic group (e.g. tolyl, mesityl) an aryl group (e.g. biphenyl), a carbonyl, a carboxylic acid, an ester, an amide, a cyano, a nitro, a thiol, a sulfoxide, and a sulfone. It is understood that the substituent may be further substituted.

[0037] The term "alkyl" as used herein is a branched or unbranched saturated hydrocarbon group of 1 to 24 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, nbutyl, isobutyl, s-butyl, f-butyl, n-pentyl, isopentyl, s-pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, eicosyl, tetracosyl, and the like. The alkyl group can be cyclic or acyclic. The alkyl group can be branched or unbranched. The alkyl group can also be substituted or unsubstituted. For example, the alkyl group can be substituted with one or more groups including, but not limited to, alkyl, cycloalkyl, alkoxy, amino, ether, halide, hydroxy, nitro, silyl, sulfo-oxo, or thiol, as described herein. A "lower alkyl" group is an alkyl group containing from one to six (e.g., from one to four) carbon atoms. A weight percent(wt. %) of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included.

[0038] The term “aralkyl” or “arylalkyl” refers to an alkyl substituted with one or more aryl groups. In certain embodiments, the aralkyl has from 7 to 30 (C7-30), from 7 to 20 (C7-20), or from 7 to 16 (C7-16) carbon atoms. Examples of aralkyl groups include, but are not limited to, benzyl, 2-phenylethyl, 3-phenylpropyl, and diphenylmethane. In certain embodiments, aralkyl are optionally substituted with one or more substituents.

[0039] The term "ester" as used herein is represented by the formula — OC(O)R or — C(O)OR, where R can be alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

[0040] As described herein, compounds of the invention may contain "optionally substituted" moieties. In general, the term "substituted," whether preceded by the term "optionally" or not, means that one or more hydrogens of the designated moiety are replaced with a suitable substituent. Unless otherwise indicated, an "optionally substituted" group may have a suitable substituent at each substitutable position of the group, and when more than one position in any given structure may be substituted with more than one substituent selected from a specified group, the substituent may be either the same or different at every position. Combinations of substituents envisioned by this invention are preferably those that result in the formation of stable or chemically feasible compounds. It is also contemplated that, in certain aspects, unless expressly indicated to the contrary, individual substituents can be further optionally substituted (i.e., further substituted or unsubstituted).

[0041] The terms “monovalent”, “divalent” and “trivalent” means a moiety with one, two and three radical centres respectively and thus can form one, two and three bonds respectively, typically C-C bonds.

[0042] Where a combination is disclosed, each subcombination of the elements of that combination is also specifically disclosed and is within the scope of the invention. Conversely, where different elements or groups of elements are disclosed, combinations thereof are also disclosed. Where any element of an invention is disclosed as having a plurality of alternatives, examples of that inventionin which each alternative is excluded singly or in any combination with the other alternatives are also hereby disclosed; more than one element of an invention can have such exclusions, and all combinations of elements having such exclusions are hereby disclosed.

[0043] Where a range of values is recited, it is to be understood that each intervening integer value, and each fraction thereof, between the recited upper and lower limits of that range is also specifically disclosed, along with each subrange between such values. The upper and lower limits of any range can independently be included in or excluded from the range, and each range where either, neither or both limits are included is also encompassed within the invention. Where a value being discussed has inherent limits, for example where a component can be present at a concentration of from 0 to 100%, or where the pH of an aqueous solution can range from 1 to 14, those inherent limits are specifically disclosed. Where a value is explicitly recited, it is to be understood that values which are about the same quantity or amount as the recited value are also within the scope of the invention, as are ranges based thereon.

[0044] Over the last few decades, the disposal of plastic waste has become a great concern in society. Recycling of waste plastics has generally been considered one of the favoured solutions to improve plastic waste management. The current recycling targets in the European Union (EU) regarding plastic packaging waste, set by Directive (EU) 2018 / 852, are 50% by 2025 and 55% by 2030. Although plastics have been recycled for a long time, the recycling rates reported are still quite low, 2020 data from the EU27+3 shows that the recycling rate has increased to nearly 35%, and 65% of post-consumer plastic waste is still sent to energy recovery or landfill. According to a new OECD report, only 9% of plastics is successfully recycled. It indicates an urgent need for an increase in plastic recycling. The development of new polymer blends and composites using waste plastic streams is of great economic importance for the recycling industry and is also significantly beneficial for global environmental health.

[0045] The mechanical recycling of post-consumer plastics is complicated by factors such as polymer degradation and incompatibility between different polymersresulting in phase separation and low-quality materials with inferior mechanical properties. One example of the dominant plastic market is multi-layer barrier packaging which is made with a variety of polymers (e g., polyolefins and EVA, PA, PET, and their ionomer polymers). These polymers are structurally different and chemically incompatible with each other. Such packaging products are difficult to recycle thermo-mechanically without any appropriate compatibilizing technology. The improvement of the mechanical performance is the key to the success of thermo-mechanical recycling of waste plastics. The goal of plastic researchers is to create and design effective performance modifying techniques that can compatibilize different immiscible resins and improve their mechanical properties.

[0046] In general, certain chemical additives can anchor along the interface and serve as efficient compatibilizers, and effectively alter the dissimilar phases and enhance the mechanical and other key properties of recycled plastics. Therefore, the development of effective compatibilization technologies is crucial in enabling polymer recycling to obtain materials with optimum performance. A suitable compatibilizer would allow multi-resins and post-consumer plastic wastes to be blended and used in more valuable applications, leading to true upcycling opportunities. Functional chemical groups and / or monomers, for example, maleic anhydride, epoxide, and glycidyl methacrylate, can interact with amine, epoxy, hydroxyl, and carboxylic acid groups via appropriate interaction mechanisms such as covalent, hydrogen bonding, or polar-polar interactions. The additives containing these reactive groups are suitable to compatibilize polar plastics (e.g., polyamides, polycarbonates, polyacrylates) with non-polar plastics (e.g., polyolefins, polystyrene). In addition, these reactive additives are effective as bridging agents or adhesion promoters between polymers and additives such as inorganic fillers or fibres. Moreover, certain reactive agents at the interface of polymer blends can create "in-situ" grafted block copolymers, which have the potential to improve the compatibilization and thus mechanical properties of polymer blends.

[0047] Most commercially available polymeric compatibilizers are modified polyolefins, which contain polar groups that enhance the chemical compatibility of polyolefins with polar polymers. BASF’s Joncryl chain extender is used as acompatibilizer with high epoxy functionality for condensation thermoplastics to increase the molecular weight, melting strength of resins which can improve the processing and mechanical properties of different plastics, which is claimed as a recyclable solution of producing hybrid materials with enhanced stiffness and toughness. The E-GMA based compatibilizers were also used in blends of rPET / PP, rPET / PE, PA / rPP, and showed improved phase dispersion and interfacial adhesion, and also increased torque and melt viscosity during melt mixing. The epoxy-based coupling agents, owing to their chemical reactivity toward nucleophilic groups, are capable of the formation of covalent linkages with various recycled polymers containing amine, alcohol, and carboxylic groups.

[0048] In mechanical recycling, the use of compatibilization techniques is relatively challenging and unpredictable because of variable waste plastic compositions. Currently, there is no one-size-fits-all strategy that exists in the mechanical recycling of all polymers. Therefore, the plastic industries need to investigate on developing appropriate additive systems based on the compositions of waste streams that can work at low concentrations to create new materials with optimum properties.

[0049] Ideally, compatibilizers are expected to compatibilize the blends of various heterogeneous plastics of waste streams and would dramatically improve key mechanical performances. Consequently, compatibilizers would upcycle the low- value plastics into new resins for high-performance applications with a longer life cycle and would result in greater economic returns. Therefore, chemical compatibilizers are the key to transforming waste plastic streams into economically sustainable materials for various applications.

[0050] Post consumer recycled plastic is recycled product from waste created by consumers. The waste is collected from kerbside and other sources from consumers and is an ideal practice for sustainability. Post industrial recycled plastic is recycled product created from scrap plastic by manufacturers and are preconsumer resins. Post industrial recycled plastic have a high level of quality and consistency. Post consumer recycled plastic has much worse quality than post industrial recycled plastic mainly due to polymer chain scission leading to asignificant drop of mechanical property, poor processability and lower chemical resistance.

[0051] Described herein is a multi-function polymer compound that can be used simultaneously as a new chain extender and a compatibilizer, a method to recycle polyolefin waste and the composition to form the polyolefin compounds. The oligomer molecule introduced to polyolefin waste is composed of a long chain polymer backbone with ester and epoxide groups to form the permanent bond and bridge between polymer chains. The chemical reaction takes place in-situ during compounding, adding value to the ease of processability. As an example, the oligomer molecule may be used in recycling and upcycling polyolefin as a pure resin and as a reinforced compound. The results show that the new chain extender and the method show similar or slightly better effect compared to the commercial chain extenders. However, the described process is much easier to perform and has a lower cost. In addition, the new chain extender is able to be the compatibilizer to enhance the interface adhesion between different types of polymers and / or between fillers and polymer matrixes. FIG. 4 shows a schematic of how a degraded polymer is repaired by the polymer compound (Linker) to form a repaired polymer.

[0052] The polymer compound, performing as a new chain extender and compatibilizer for polyolefin waste, by following composition of raw materials: (a) Modified polyolefin with weight average molecular weight (Mw) between 2,000 - 250,000; (b) Aliphatic and / or aromatic di-, tri- tetra- epoxide based compounds; and (c) Aliphatic and / or aromatic secondary, tertiary amine compounds. The amine compound may serve as a catalyst in the reaction. The polyolefin may be substituted with a polyacrylate.

[0053] FIG. 2 shows a generic form of the polymer compound. The X1and X2monomers forms the modified polyolefin as indicated in FIG. 2. The polymer is a graft polymer. X1and X2may be considered to form a polymer backbone in the graft polymer. The modified polyolefin may be a polymer with a grafted polar functional group. In an embodiment, X1is the original polyolefin and X2is the polyolefin grafted with a polar functional group which is attached to an epoxy-containing moiety or block. Examples of a suitable polymer backbone includes polypropylene andpolyethylene. The X2monomer in the polymer backbone may be in any order as per a graft polymer. The grafted monomer may be in random sequence, in a repeating sequence, a block type polymer, or combinations thereof. In an embodiment, the polar functional group is one or more esters and the linking carbon atoms bonded to the polyolefin backbone (X3). The one or more esters may be formed by reacting polypropylene with a,|3-unsaturated acid anhydrides and esters such as maleic anhydride, hydroxyl, carboxylic, carboxylate derivatives, citraconic anhydride, endo- bi-cyclo[2,2, 1 }-1 ,4,5,6,7,7-hexa-chloro-5 heptene-2,3-dicarboxylic acid anhydride, endo-bi cyclo[2,2,1]-5-heptene-2,3-dicarboxylic acid anhydride, cis-4-cyclohexene- 1 ,2-dicarboxylic acid anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, or maleate esters (monoester and diester) to form the grafted polypropylene. Hence, X3may vary depending on the a,|3-unsaturated acid anhydrides and esters used. In an embodiment, X2and optionally X1may be poly(methyl methacrylate) or polyacrylate and the ester (X3) may be bonded directly to the polyolefin backbone. The amount of the modified polyolefin may be in the range of 50 to 95 percentages by weight (wt. %) of the total composite composition after combination with the plastic to be recycled.

[0054] The epoxide-based compound (X4) may be a polymerisable resin of an epoxy-containing monomer, oligomer, prepolymer or any combination thereof. The polymerizable binder may be selected from the bisphenol A type epoxy resin, bisphenol S type epoxy resin, bisphenol F type epoxy resin, phenolic novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resins (such as triglycidyl isocyanuric and hydantoin epoxy), hydrogenated bisphenol A type epoxy resin, aliphatic epoxy resins (such as propylene glycoldiglycidyl ether and pentaerythritolpolyglycidyl ether), and combinations thereof. The polar functional group (X3) and the epoxide-based component (X4) may be considered to form the grafted portion of the polymer.

[0055] The amine compound is a compound of monoamine, diamine, tri-amine, or polyamine with an aliphatic and / or aromatic component and serves as a catalytic agent for the and may be aliphatic, aromatic and / or alicyclic anhydrous compounds.For example, the catalytic agent may be a compound of organic-acid hydrazide, triaryl sulfonium salt, dicyandiamide, boron trifluoride-amine complex, polymercaptan, imidazoles, tertiary amines, secondary amines, and / or polyamide resin. The amine compound may be used as one of the catalytic agents for to boost the reaction with the linker compound.

[0056] Depending on how the polymer is prepared and the amount of reagents used, not all of the ester may be bonded to the epoxide-based component. The polymer may be represented by Formula 1 , Formula 2, and Formula 3.ormu aFormula 3In Formula 1 , Formula 2, and Formula 3, x is from 50 to 5000, yi is from 5 to 500, y? is from 0 to 100, yi + y2 is from 5 to 500, R1is CHs or H, R2is a trivalent hydrocarbon having 2 to 20 carbon atoms which is optionally substituted with one or more heteroatoms or functional groups, R3is a divalent hydrocarbon having 2 to 20 carbon atoms which is optionally substituted with one or more heteroatoms or functional groups, R4is a monovalent hydrocarbon having 1 to 20 carbon atoms which is optionally substituted with one or more heteroatoms or functional groups, Z1and Z2if present is each independently selected from the group consisting ofdivalent hydrocarbon having 2 to 20 carbon atoms which is optionally substituted, ai is from 5 to 50. The hydrocarbon may be an aliphatic moiety (including both saturated and unsaturated), an aryl moiety, aralkyl, including alkyl, and combinations thereof. Common examples of heteroatoms that may be present include oxygen, nitrogen, and sulphur. Common examples of functional groups that may be present include ester, amide, ether, hydroxyl, amine, and halogen. In some embodiments, R1is methyl (CH3). In some embodiments, R1is hydrogen (H). Insome embodiments, y2 is zero (0), in other words the grafted functional groups are each bonded to the epoxide component, and may depend on the method of preparing the polymer and the molar ratio of the reagents used. In some embodiment, R2and R3(where applicable) is a divalent alkyl moiety having 2 to 10 carbon atoms optionally substituted with one or more heteroatoms or functional groups, preferably the divalent alkyl moiety has 2 to 6 carbon atoms optionally substituted with one or more heteroatoms or functional groups.

[0057] In an example, the polymer is of Formula 1 . In Z1, R5, R6, R7, and R8may each independently have 2 to 6 carbon atoms and each independently a divalent substituted alkyl moiety or a divalent unsubstituted alkyl moiety, in Z2R5, R6, R7, and R8are each having 6 to 20 carbon atoms and independently selected from the group consisting of a divalent substituted aralkyl moiety, a divalent unsubstituted aralkyl moiety, a divalent substituted aryl moiety, and a divalent unsubstituted aryl moiety.

[0058] In an embodiment,. In an embodiment, R6and R7are each a divalent unsubstituted alkyl moiety with 2 to 6 carbon atoms or a divalent substituted alkyl moiety with 2 to 6 carbon atoms. In an embodiment, R7may be a divalent unsubstituted alkyl moiety with 2 to 6 carbon atoms and R6may be -CH2CH(OH)CH2- In an embodiment, R7may be a divalent unsubstituted alkyl moiety with 2 to 4 carbon atoms.

[0059] In an embodiment, Z2maythe divalent substituted or unsubstituted aralkyl moiety of R8is selected from the group consisting of a divalent bisphenol moiety, a divalent phenol novolak moiety, and a divalent cresol novolak moiety. Examples of the divalent bisphenol include bisphenol A, bisphenol S, and bisphenol F.

[0060] An example of the functional polymer is the polymer of Formula 4 (also termed Linker herein) which is shown below and in FIG. 3:

[0061] Formula 4, where x is from 50 to 5000. Each of y, m, and n may each be independently selected from 5 to 500. In an embodiment, y, m and n is each independently selected from 5 to 200. In an embodiment, y, m and n where applicable is each independently selected from 5 to 100. In an embodiment, y, m and n where applicable is each independently selected from 5 to 50. In an embodiment, x is from 50 to 4000. In an embodiment, x is from 50 to 3000. In an embodiment, x is from 50 to 1000. In an embodiment, x is from 50 to 500. In an embodiment, the polymer of Formula 4 has a polyethylene backbone instead of the polypropylene backbone of Formula 4.

[0062] In an example, the polymer is of Formula 2. In Z1, R5, R6, R7, and R8are each independently selected from the group consisting of a divalent substituted alkyl moiety having 2 to 6 carbon atoms, a divalent unsubstituted alkyl moiety having 2 to 6 carbon atoms, a divalent substituted aralkyl moiety having 6 to 20 carbon atoms, a divalent unsubstituted aralkyl moiety having 6 to 20 carbon atoms, a divalent substituted aryl moiety having 6 to 20 carbon atoms, and a divalent unsubstituted aryl moiety having 6 to 20 carbon atoms.

[0063] In an example, the polymer is of Formula 3. R4may be methyl or ethyl. In Z1, R5, R6, R7, and R8are each independently selected from the group consisting of a divalent substituted alkyl moiety having 2 to 6 carbon atoms, a divalentunsubstituted alkyl moiety having 2 to 6 carbon atoms, a divalent substituted aralkyl moiety having 6 to 20 carbon atoms, a divalent unsubstituted aralkyl moiety having 6 to 20 carbon atoms, a divalent substituted aryl moiety having 6 to 20 carbon atoms, and a divalent unsubstituted aryl moiety having 6 to 20 carbon atoms.

[0064] The polymer of Formula 1 , Formula 2, Formula 3, and Formula 4 may be prepared by any suitable method to prepare the graft polymer, including but not limited to atom transfer radical polymerisation, ring-opening metathesis polymerisation, anionic and cationic polymerisations, and free radical living polymerisation, radiation-induced polymerization, polycondensation reactions, and iniferter-induced polymerization. The epoxide containing component may be attached by conventional esterification reactions, for example with a coupling reagent, or via the acid chloride or acid anhydride.

[0065] As an example, the polypropylene is first grafted with maleic anhydride with the required amount to form maleic anhydride grafted polypropylene. The maleic anhydride grafted polypropylene is subsequently reacted with the epoxy containing components. For example, the maleic anhydride grafted polypropylene may be reacted with the glycerol-polybutanediol-glycidyl resin and the glycerolbisphenol A-glycidyl resin to provide the polymer of Formula 4. Similarly, the polyethylene equivalent may be prepared by using maleic anhydride grafted polyethylene. Alternatively, polypropylene may be grafted with fumarate ester or maleate ester (or their carboxylic acid). The esters may the methyl or ethyl esters or bonded to the required glycidyl resins. The polymers of other formulas may be prepared by the same general methods.

[0066] The reagents and raw materials may be combined with the polyolefin waste in which the molten stage mixing process is selected from extrusion, and batch mixing to form a polymer blend. The amount of the Linker polymer (Formulas 1 to 4) in the polymer blend (processed product) may be in the rage of 0.1-50 wt.%. It will be preferable to use as little of the polymer of Formulas 1 to 4 to minimise the costs and to maximise the amount of plastic that is recycled. Hence, preferred quantities of the polymer in the polymer blend may be from 1 to 10 wt.% or from 1 to 5 wt.%. The recycled plastic composite product may be used in transportationapplications (such as aerospace, automotive, train), infrastructure applications (such as pipe, tank), consumer goods (such as packaging, sporting goods, electronics) and construction applications.

[0067] Materials and compounding

[0068] A commercial grade virgin PP (SCGC PP P902J) is used as a control and is homogeneous polypropylene with MFR of 60 g / 10min (230 °C, 2.16 kg). Virgin PP 902J was exposed under UV lighter at 65 °C, 0.55 w / m2for 1 week, and was regarded as a substitute for post customer recycled (PCR) (termed PP(PCR) herein) resin.

[0069] Bisphenol-A based epoxies were purchased from Huntsman, weight per Epoxide (EEW, g / eq) range from 300 to 500. The specific epoxies mixed with maleic anhydride oligomers and termed as linker herein.

[0070] EBA-GMA (GRAFTABOND EB-GMA 01050 IM / C) and Joncryl ADR (BASF Joncryl ADR 4468) chain extender are the typical and commercially available chain extender, their structures as well as present invention developed chain extender are shown in FIG. 1. EBA-GMA is a copolymer of ethylene and butyl acrylate, grafted with a high amount of Glycidyl Methacrylate. Joncryl ADR is a styrene-acrylate-glycidyl methacrylate copolymer.

[0071] Prior to compounding, PP(PCR) was dried at 80 °C for 6 h in a vacuum oven to minimise hydrolytic degradation, the mixture of different samples was mixed vigorously, and melt compounding was performed using a twin-screw extruder (Thermo Scientific EuroLab 16mm) under 160~200 °C and at a rate of 100 rpm. The composition of samples comprising PP(PCR), glass fibre (GF), maleic anhydride grafted polypropylene (POLYBOND 3002, MAPP), and different chain extenders are summarised in Table 1. The MAPP used here may be the same or different from the maleic anhydride grafted polypropylene used to prepare the polymer of Formulas 1 to 4. MAPP may be replaced by any maleic anhydride grafted polyolefin, and it is preferable that the polyolefin used is the same as that in the polymer.

[0072] The composition of PP(PCR), MAPP, GF, epoxide component, and catalytic component were mixed using high speed mixer for a period of time and at a certain speed. After mixing, the mixture was compounded via a twin-screwextruder which effectively provided the high shear force to boost the chemical reaction between PCR and chain extenders. The twin screw L / D ratio, screw configurations, extrusion time, extrusion speed, extrusion temperature and other extrusion conditions may be suitably selected depending on the particular purposes.

[0073] The Linker polymer used for the composition in the following examples is the polymer of Formula 4 with x is from 50 to 500, y is from 5 to 50, m is from 5 to 50, and n is from 5 to 50.

[0074] Table 1. Composition of PP(PCR) and PP(PCR) / GF composites (each component is provided as mass percentage in each example)

[0075] Characterisation

[0076] The mechanical performance of composites was conducted on an Instron 5569 test machine for tensile and flexible properties. Tensile tests were performed with load cell 50 kN at a crosshead speed of 1 mm / min according to ASTM D638. Flexural tests were performed at a crosshead speed of 1.2 mm / min according to ASTM standard D790. The length of the support span was 48 mm. The interfacial morphology between GF and PP(PCR) was observed by Field Emission Scanning Electron Microscope (FESEM) JEOL-6700F. The injection moulded samples were cryo-fractured in liquid nitrogen.

[0077] The shear viscosity of PP(PCR) and the extending samples were measured using a capillary rheometer (Rosand RH2000) to monitor the viscosity change after introducing linker, which indicates the molecule structure change. Thetest was carried out in the shear rate range of 5 - 1000 s-1at 200°C at a fixed strain of 10% for all samples.

[0078] Mechanical Properties of PP(PCR) and PPfPCRVGF Composites

[0079] Mechanical tests on PP(PCR) and GF reinforced PP(PCR) composites with different chain extenders were performed to evaluate its effects on mechanical performance. The results are showed in FIG. 5A, FIG. 5B, FIG. 6A and FIG. 6B. It is worth to note that the introduction of chain extender into PP(PCR) induced increase in the tensile (FIG. 5B and FIG. 6B) and flexural strength (FIG. 5A and FIG. 6A) significantly. The strength performance can be improved to the similar level of virgin PP. Moreover, the improvement of linker is bigger than those of other typical chain extenders. The same trend was obtained in both PP(PCR) and PP(PCR) / GF composites as shown in FIG. 5A, FIG. 5B, FIG. 6A and FIG. 6B.

[0080] FIG. 7 shows the morphology of PP(PCR) / GF without (FIG. 7A) and with linker (FIG. 7B). It is clear from FIG. 7 that the linker enhances the bonding interaction between PP(PCR) and GF. The morphology observation is in agreement with the mechanical performance reported above and provided further evidence that the linker induces strong interaction between GF and PP matrix, therefore enhanced the mechanical properties. The matrix is homogeneous and shows no presence of separation of linker phase or agglomeration of epoxy particles. This suggests that the improvement of the mechanical property of recycled PP and PP / GF is not due to the rigid epoxy particle reinforced PP but due to the strong interface adhesion between PP and GF for PP(PCR) / GF compound and increase of molecular size (refer to below data in Table 2).

[0081] Rheology Properties of PP(PCR) / Linker

[0082] The shear viscosity of the samples with different chain extenders at different shear rates was measured against that of the unmodified control and is shown in Table 2.

[0083] Table 2. The shear viscosity comparison of PP(Virgin), PP(PCR) and PP(PCR) / Linker

[0084] The PP (virgin) shows the highest shear viscosity, indicating the material's original molecular weight. The results in PP(PCR) show a significant drop in shear viscosity after UV treatment, which indicates a decrease in the molecular weight of virgin PP. The viscosity increased significantly after the chain extender was introduced. The viscosity increase indicates that the reaction occurrence of chain extender with the end reactive group of PCRs and leads to the increase of molecular weight.

[0085] Overall performance of typical chain extenders

[0086] The comparison of performance of typical commercially chain extenders and linker in PP(PCR) / GF composites are described in Table 3. The Linker is the most effective in terms of mechanical performance and processibility and has the lowest cost per kilogram. Nature colour may also be termed plain colour and means there is no significant change compared to the original colour.

[0087] Table 3. Performance comparison for typical chain extenders'0088] Comparative example 1

[0089] The chain extenders with different loadings were tried in PP(PCR), the composition and the effects on chain extenders on mechanical properties are shown in Table 4 and 5. The addition of a chain extender has significant effects on the mechanical properties of PP(PCR). However, the loading with 2.5wt% or 5wt% of the different chain extenders only has slight effects.

[0090] Table 4. Composition of PP(PCR) with different chain extenders

[0091] Table 5. Mechanical properties of PP(PCR) with different chain extenders

[0092] Comparative example 2

[0093] The present invention linker was applied in recycled polypropylene and recycled polyethylene (rPP / rPE) and rPP / rPE / GF composites. The rPP and rPE used are from post-consumer recycled resins without further characterisation. The composition and the mechanical properties are shown in Table 6 and Table 7. The introduction of linker into rPP / rPE or rPP / rPE / GF enhanced the strength obviously compared to the control without linker.

[0094] Table 6. Composition of rPP / rPE and rPP / rPE / GF with Linker

[0095] Table 7. Mechanical properties of rPP / rPE and rPP / rPE / GF with Linker

Claims

CLAIMS

1. A polymer selected from the group consisting of Formula 1 , Formula2, and Formula 3,ormu a , x is from 50 to 5000, yi is from 5 to 500, y2 is from 0 to 100, yi + y2 is from 5 to 500, R1is CH3or H,R2is a trivalent hydrocarbon having 2 to 20 carbon atoms which is optionally substituted with one or more heteroatoms or functional groups,R3is a divalent hydrocarbon having 2 to 20 carbon atoms which is optionally substituted with one or more heteroatoms or functional groups, R4is a monovalent hydrocarbon having 1 to 20 carbon atoms which is optionally substituted with one or more heteroatoms or functional groups,Z1and Z2if present is each independently selected from the group consisting ofare each independently a divalent hydrocarbon having 2 to 20 carbon atoms which is optionally substituted, ai is from 5 to 500.

2. The polymer according to claim 1 , wherein the polymer is of Formula 1 ,Formula 1 , wherein in Z1, R5, R6, R7, and R8are each independently having 2 to 6 carbon atoms and each independently selected fromthe group consisting of a divalent substituted alkyl moiety or a divalent unsubstituted alkyl moiety, wherein in Z2, R5, R6, R7, and R8are each independently having 6 to 20 carbon atoms and each independently selected from the group consisting of a divalent substituted aralkyl moiety, a divalent unsubstituted aralkyl moiety, a divalent substituted aryl moiety, and a divalent unsubstituted aryl moiety.

3. The polymer according to claim 2, wherein Z1is, preferably R6and R7are each a divalent unsubstituted alkyl moiety with 2 to 6 carbon atoms or a divalent substituted alkyl moiety with 2 to 6 carbon atoms, more preferably R6is -CH2CH(OH)CH2- and R7is the divalent unsubstituted alkyl moiety with 2 to 6 carbon atoms.

4. The polymer according to claim 2 or claim 3, wherein Z2is, the divalent substituted or unsubstituted aralkyl moiety of R8is selected from the group consisting of a divalent bisphenol moiety, a divalent phenol novolak moiety, and a divalent cresol novolak moiety.

5. The polymer according to claim 4, wherein the divalent bisphenol moiety is selected from the group consisting of bisphenol A, bisphenol S, and bisphenol F.

6. The polymer according to claim 1 , wherein the polymer is of FormulaFormula 2, wherein in Z1, R5, R6, R7, and R8are each independently selected from the group consisting of a divalent substituted alkyl moiety having 2 to 6 carbon atoms, a divalent unsubstituted alkyl moiety having 2 to 6 carbon atoms, a divalent substituted aralkyl moiety having 6 to 20 carbon atoms, a divalent unsubstituted aralkyl moiety having 6 to 20 carbon atoms, a divalent substituted aryl moiety having 6 to 20 carbon atoms, and a divalent unsubstituted aryl moiety having 6 to 20 carbon atoms.

7. The polymer according to any one of claims 1 to 6, wherein R2and R3where applicable is a divalent alkyl moiety having 2 to 10 carbon atoms optionally substituted with one or more heteroatoms or functional groups, preferably the divalent alkyl moiety having 2 to 6 carbon atoms optionally substituted with one or more heteroatoms or functional groups.

8. The polymer according to claim 1 , wherein the polymer is of FormulaZ1, R5, R6, R7, and R8are each independently selected from the group consisting of a divalent substituted alkyl moiety having 2 to 6 carbon atoms, a divalent unsubstituted alkyl moiety having 2 to 6 carbon atoms, a divalent substituted aralkyl moiety having 6 to 20 carbon atoms, a divalent unsubstituted aralkyl moiety having 6 to 20 carbon atoms, a divalent substituted aryl moiety having 6 to 20 carbon atoms, and a divalent unsubstituted aryl moiety having 6 to 20 carbon atoms.

9. The polymer according to any one of claims 1 to 8, wherein R1is CHs.

10. The polymer according to any one of claims 1 to 9, wherein y2 is 0.

11. The polymer according to any one of claims 1 to 10, wherein y1and ai is each independently selected from 5 to 200, preferably y1and ai is each independently selected from 5 to 100, more preferably y1and ai is each independently selected from 5 to 50.

12. The polymer according to any one of claims 1 to 5, wherein the polymer is of Formula 4,Formula 4, x is from 50 to 5000, y, m, and n is each independently selected from 5 to 500.

13. The polymer according to claim 12, wherein y, m and n is each independently selected from 5 to 200, preferably y, m and n is each independentlyselected from 5 to 100, more preferably y, m and n is each independently selected from 5 to 50.

14. The polymer according to any one of claims 1 to 13, wherein x is from 50 to 4000, preferably x is from 50 to 3000, more preferably x is from 50 to 1000, even more preferably x is from 50 to 500.

15. A polymer blend comprising the polymer according to any one of claims 1 to 14 and a second polymer.

16. The polymer blend according to claim 15, wherein the polymer is present in 0.1 to 50 wt.% of the polymer blend.

17. The polymer blend according to claim 16, wherein the polymer is present in 1 to 10 wt.% of the polymer blend.

18. The polymer blend according to any one of claims 15 to 17, wherein the second polymer is a used polymer and the polymer reacts with the used polymer.

19. The polymer blend according to any one of claims 15 to 18 further comprises maleic anhydride grafted polyolefin and / or glass fibres.

20. The polymer blend according to any one of claims 15 to 19 further comprises a third polymer which is different from the second polymer.

21. A method of producing a polymer blend, the method comprises mixing the polymer according to any one of claims 1 to 14 and a second polymer to produce the polymer blend, wherein the mixing step is a molten stage mixing process and is by extrusion or batch mixing.

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