Reinforced polyethylene reclaimed material modified composition, material, and preparation method and application thereof

Abstract

The invention relates to a reinforced polyethylene reclaimed material modified composition, a material and a preparation method and application thereof. The modified composition comprises the following components: a polyethylene reclaimed material, a chemical modifier, a nano reinforcing agent, a stabilizer and a functional filler, the chemical group modifier is polyethylene grafted maleic anhydride, an ethylene-vinyl acetate copolymer or polymethyl methacrylate; the nano reinforcing material is a carbon nano tube, graphene or nano silicon dioxide; the functional filling agent is carbon fiber, glass fiber or nano clay. Compared with the prior art, the invention has the advantages of high tensile strength, high bending strength, strong thermal stability, strong long-term weather resistance and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material modification, and particularly relates to a reinforced polyethylene recycled material modification composition, a material, and a preparation method and application thereof. Background Art

[0002] As a widely used plastic material, polyethylene is favored for its light weight, durability, and cost-effectiveness. However, with the increasing usage, the environmental problems of waste polyethylene are becoming increasingly serious. The performance of traditional polyethylene recycled materials is poor, which limits their use in enhanced application fields. Therefore, it is particularly important to develop a modification method that can effectively improve the performance of polyethylene recycled materials.

[0003] Patent Publication No. CN107973954A discloses a reinforced modified polyethylene recycled material and a preparation method thereof. Maleic anhydride grafted polypropylene wax is added to the polyethylene recycled material to introduce strongly polar reactive groups, and finally the obtained composition has good dispersibility, compatibility, and excellent rigidity-flexibility balance. However, maleic anhydride grafted polypropylene wax only serves as a compatibilizer, and the main purpose is to improve the interfacial compatibility between different polymers, without improving the intrinsic properties of the polyethylene recycled material, and there are technical limitations such as high glass fiber density and interface bonding relying on polar grafting.

[0004] Patent Publication No. CN118852828A discloses a high-density polyethylene composite material for corrugated pipes and a preparation method thereof. By modifying graphene oxide and then combining it with carbon nanotubes to obtain a hybrid, and mixing it with grafted polyethylene to obtain modified polyethylene, and then mixing it with other additives and extruding and pelletizing to obtain the composite material. However, this material is for high-density polyethylene corrugated pipes, and it is necessary to solve the problem of carbon nanotube dispersion, and it relies on a complex modification hybridization process and relies on polar group grafting modification for compatibility, without involving the performance improvement of polyethylene recycled materials.

[0005] Patent Publication No. CN110628108A discloses a low thermal expansion coefficient type waste plastic synthetic sleeper, including: 100 parts of base resin, 35 - 55 parts of thermal expansion coefficient modifier, 5 - 10 parts of compatibilizer, 30 - 60 parts of flame retardant, 45 - 70 parts of reinforcing filler, 0 - 1 part of anti-ultraviolet light additive, 0 - 2 parts of anti-ultraviolet light additive, 1.0 - 2.5 parts of coupling agent, 0 - 3 parts of lubricant, 0 - 4 parts of foaming agent. The thermal expansion coefficient modifier is one or a mixture of hollow glass microspheres, negative thermal expansion coefficient materials, rare earth oxides, waste rubber powder, glass fibers, carbon fibers, glass fiber reinforced polyethylene, and glass fiber reinforced polypropylene. However, carbon fiber as a thermal expansion modifier does not solve the problem of its dispersion in polyethylene. Summary of the Invention

[0006] The object of the present invention is to overcome the deficiencies of the existing technologies in terms of insufficient thermal stability and long-term weather resistance, and to provide an enhanced polyethylene recycled material modification composition, material, its preparation method and application, so as to obtain an enhanced polyethylene recycled material modification material with high tensile strength, high flexural strength, strong thermal stability and strong long-term weather resistance.

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] One of the technical solutions of the present invention is to provide an enhanced polyethylene recycled material modification composition, which includes the following components: polyethylene recycled material, chemical-based modifier, nano-enhancer, stabilizer, functional filler;

[0009] The chemical-based modifier includes polyethylene grafted maleic anhydride (PE-g-MAH), ethylene-vinyl acetate copolymer (EVA) or polymethyl methacrylate (PMMA);

[0010] The nano-enhancing material includes carbon nanotubes, graphene or nano-silica;

[0011] The functional filler includes carbon fiber, glass fiber or nano-clay.

[0012] Through the synergistic action mechanism of multi-component materials, from molecular structure regulation to microscopic interface design, the present invention significantly improves the comprehensive performance of polyethylene recycled materials. As the core component, the chemical-based modifier optimizes the interfacial compatibility and molecular chain interaction through different mechanisms. The maleic anhydride group of PE-g-MAH forms a covalent bond graft with the end of the polyethylene molecular chain, which improves the surface energy and enhances the interfacial binding with nano-fillers through hydrogen bonds; the vinyl acetate chain segment of EVA forms a π-π conjugation with the nano-material through the polar ester group, and the flexible chain segment absorbs impact energy to achieve a balance between rigidity and toughness; PMMA coats graphene with a rigid skeleton to inhibit agglomeration and improve the flexural modulus. Carbon nanotubes span crystal regions and bridge molecular chains with a high aspect ratio, inducing orientation arrangement to improve tensile strength and increasing the thermal diffusion coefficient through a three-dimensional heat conduction network; the two-dimensional sheet structure of graphene blocks crack propagation and oxygen penetration, prolonging the oxidation induction period; nano-silica forms a percolation network through surface hydroxyl groups, increasing the storage modulus. The composite stabilizer system efficiently captures free radicals through hindered phenolic antioxidants, and the hindered amine light stabilizer cycles and regenerates to shield ultraviolet degradation. Among the functional fillers, carbon fiber transfers stress directionally along the extrusion direction, reducing the coefficient of thermal expansion; the intercalated structure of nano-clay blocks water and oxygen penetration, and the retention rate of flexural strength after hygrothermal aging is improved.

[0013] Further, by mass parts, the modified composition comprises 100 parts of polyethylene recycled material, 2 - 20 parts of chemical base modifier, 0.1 - 2 parts of nano enhancer, 2 - 6 parts of stabilizer, and 5 - 30 parts of functional filler.

[0014] Further, the polyethylene recycled material is obtained by cleaning and crushing polyethylene waste.

[0015] Further, the source of the polyethylene waste is waste polyethylene film.

[0016] Further, the stabilizer is a combination of an antioxidant and a light stabilizer with a mass ratio of 1:0.5 - 1; the antioxidant can prevent the thermal oxidative degradation of the polyethylene recycled material during processing and use, while the light stabilizer can absorb ultraviolet rays to prevent the photo - degradation of the polyethylene recycled material;

[0017] The antioxidant includes n - octadecyl 3,5 - di - tert - butyl - 4 - hydroxybenzoate, 4,4'-thiobis(6 - tert - butyl - 3 - methylphenol), tris(2,4 - di - tert - butylphenyl) phosphite;

[0018] The light stabilizer includes 2 - (2'-hydroxy - 5'-methylphenyl) benzotriazole, 2 - hydroxy - 4 - n - octyloxybenzophenone, 2,4 - di - tert - butylphenol.

[0019] Furthermore, the molecular weight of the antioxidant is 350 - 650.

[0020] The second technical solution of the present invention lies in providing a preparation method of an enhanced polyethylene recycled material modified material, which is carried out with the components in the described enhanced polyethylene recycled material modified composition, and includes the following steps:

[0021] S1. First, mix the chemical base modifier and the nano enhancer to obtain a first mixture;

[0022] S2. Add the stabilizer to the first mixture for a second mixing to obtain a second mixture;

[0023] S3. Add the polyethylene recycled material to the second mixture for a third mixing to obtain a third mixture;

[0024] S4. Add the functional filler to the third mixture for a fourth mixing to obtain an intermediate product;

[0025] S5. Extrusion - mold the intermediate product to obtain the enhanced polyethylene recycled material modified material.

[0026] Further, in step S1, the stirring rate of the first mixing is 200 - 250 rpm, and the temperature is 80 - 110 °C.

[0027] Further, in step S2, the stirring rate of the second mixing is 300 - 350 rpm, and the temperature is 120 - 150 °C.

[0028] Further, in step S3, the stirring rate of the third mixing is 350 - 400 rpm, and the temperature is 120 - 150 °C.

[0029] Further, in step S4, the stirring rate of the fourth mixing is 100 - 150 rpm, and the temperature is 60 - 80 °C.

[0030] Further, in step S5, the specific parameters of the extrusion molding process are: extrusion temperature 160 - 180 °C, head pressure 5 - 15 MPa, screw speed 50 - 150 rpm, die temperature 170 - 190 °C, residence time of the material in the die 10 - 30 seconds, and water cooling and shaping at 20 - 40 °C.

[0031] Further, the chemical base modifier can improve the compatibilizer and processing performance of the polyethylene recycled material, and pretreatment is required during use to ensure its uniform dispersion in subsequent mixing steps.

[0032] Even further, the pretreatment step includes preheating at a temperature of 80 - 110 °C to soften the material, and pre-stirring at a certain speed in a stirrer to ensure the uniformity of its internal components.

[0033] The third technical solution of the present invention lies in providing a modified material for enhanced polyethylene recycled material, which is prepared by the described preparation method.

[0034] The fourth technical solution of the present invention lies in providing an application of the modified material for enhanced polyethylene recycled material in the field of enhanced plastic products.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] (1) The quadruple synergistic mechanism significantly improves the comprehensive performance: Through the synergistic effect of the chemical bonding - physical entanglement double network (modifier), multi-scale reinforcement path (nano material), self-healing stabilization mechanism (stabilizer), and microstructure regulation (filler), the material performance of the present invention is significantly better than that of traditional modification systems. The material performance of the present invention has a tensile strength of 20 - 30 MPa, a flexural strength of 12 - 20 MPa, an impact strength of 45 - 55 KJ / m 2 , an elongation at break of 420% - 460%, and 2 - 7 impurity points per m 2 .

[0037] (2) Multi-dimensional Synergy between Chemical Group Modifiers and Nano-Reinforcing Agents: Compared with the mechanical mixing of a single modifier in existing patents, the present invention realizes the dual optimization of molecular chain recombination and interface enhancement through the synergistic effect of chemical group modifiers (such as PE-g-MAH, EVA, PMMA) and nano-reinforcing agents (carbon nanotubes, graphene, etc.). The maleic anhydride groups of PE-g-MAH form chemical bonds (hydrogen bonds and π-π conjugation) with the surface of carbon nanotubes, and its synergistic effect increases the tensile strength by 30%-35% compared with nano-clay (Example: Example 1 vs Comparative Example 6 = 25 MPa vs 19 MPa); while the flexible segments of EVA and the two-dimensional sheets of graphene form a three-dimensional network through physical entanglement, and the impact strength is increased by 10%-20% compared with the use of SEB (Example: Example 2 vs Comparative Example 7 = 51 KJ / m 2 vs 44 KJ / m 2 ). In contrast, non-polar modifiers such as SEBS in the prior art are difficult to form effective interfacial bonds with nano-materials, resulting in uneven dispersion and performance bottlenecks.

[0038] (3) Complementary Synergy between Stabilizers and Functional Fillers: In the prior art, stabilizers and fillers mostly act independently, while the present invention forms complementary synergy through the dynamic regeneration mechanism of hindered phenolic antioxidants and light stabilizers, combined with the microstructure barrier effect of functional fillers (such as carbon fiber, nano-clay). Among them, the stabilizer (a combination of antioxidant and light stabilizer) increases the flexural strength by 20%-25% compared with the case without stabilizer (Example: Example 3 vs Comparative Example 4 = 16 MPa vs 13 MPa).

[0039] (4) Multi-scale Synergistic Enhancement between Nano-Reinforcing Agents and Functional Fillers: The present invention breaks through the simple compounding of nano-materials and macroscopic fillers in the prior art. Through the multi-scale synergy of carbon nanotubes (bridging with high aspect ratio) and carbon fibers (stress directional transfer), the tensile strength is increased by 100%-110% compared with a single reinforcement system (Example: Example 1 vs Comparative Example 8 = 25 MPa vs 12 MPa), and the flexural strength is increased by 40%-45% compared with common nano-clay (Example: Example 1 vs Comparative Example 6 = 14 MPa vs 10 MPa).

[0040] In summary, through the synergistic innovation of multiple components at the molecular-interface-micro-macro multi-scale, the present invention realizes the comprehensive improvement of the performance of recycled polyethylene materials, and its comprehensive performance is significantly better than the single or simple compounding modification schemes in the prior art. Detailed Implementation Modes

[0041] The present invention will be described in detail below in conjunction with specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments. Based on the given embodiments, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application.

[0042] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art.

[0043] In the following embodiments, the polyethylene recycled material is obtained by cleaning and crushing polyethylene film into 10 mm square pieces. The thickness of the polyethylene film is 0.02 - 0.05 mm, and the density is 0.91 - 0.93 g / cm 3 .

[0044] The CAS number of polyethylene grafted maleic anhydride is 9006 - 26 - 2, and the average molecular weight is 378.33. It is purchased from Shanghai Macklin Biochemical Co., Ltd. The CAS number of ethylene-vinyl acetate copolymer is 24937 - 78 - 8, and the average molecular weight is 342.43. It is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The CAS number of polymethyl methacrylate is 9010 - 88 - 2, and the average molecular weight is 200.23. It is purchased from Henan Tianfu Chemical Co., Ltd.

[0045] The CAS number of carbon nanotubes is 16291 - 96 - 6, the molecular weight is 12.01, the carbon nanotube content is ≥95%, the diameter is 20 - 40 nm, and the length is 1 - 2 μm. It is purchased from Shanghai Macklin Biochemical Co., Ltd. The CAS number of graphene is 1034343 - 98 - 0, the molecular weight is 16.04, it is a powder, the graphene sheet diameter is 0.3 - 10 μm, and the thickness is 1 - 5 atomic layer. It is from Shanghai Macklin Biochemical Co., Ltd. The CAS number of nano-silica is 60676 - 86 - 0, the molecular weight is 60.08, and the specific surface area is ≥450 m 2 / g. It is purchased from Shanghai Macklin Biochemical Co., Ltd.

[0046] The carbon content of carbon fiber is ≥95%, the tensile strength is ≥3.5 MPa, and the density is 1.75 - 2.0 g / cm 3 , and it is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The CAS number of glass fiber is 65997 - 17 - 3, the tensile strength is ≥2.0 MPa, and the density is 2.5 - 2.7 g / cm 3, with a heat resistance of ≥600 °C, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The CAS number of the nano-clay is 1318-93-0, (related properties: montmorillonite type, layer spacing 1.2 - 1.5 nm, specific surface area ≥700 m 2 / g, particle size ≤50 nm), purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0047] The antioxidant in Example 1 is n-octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, with a CAS number of 2082-79-3, (molecular weight: 530.86, purity ≥98%, white powder, melting point 50 - 55 °C), purchased from Sinopharm Chemical Reagent Co., Ltd.; the light stabilizer is 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, with a CAS number of 2440-22-4, (molecular weight: 225.25, purity ≥99%, light yellow crystal, melting point 125.5 - 129.5 °C), purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0048] The antioxidant in Example 2 is 4,4'-thiobis(6-tert-butyl-3-methylphenol), with a CAS number of 96-69-5, (molecular weight: 358.54, purity ≥95%, light yellow granules, melting point 160 - 165 °C), purchased from Shanghai Macklin Biochemical Co., Ltd.; the light stabilizer is 2-hydroxy-4-n-octyloxybenzophenone, with a CAS number of 1843-05-6, (molecular weight: 326.43, purity ≥97%, light yellow liquid, melting point 47 - 49 °C), purchased from Shanghai Macklin Biochemical Co., Ltd.

[0049] The antioxidant in Example 3 is tris(2,4-di-tert-butylphenyl) phosphite, with a CAS number of 31570-04-4, (molecular weight: 646.94, purity ≥96%, white powder, melting point 180 - 185 °C), purchased from Abbexa (Shanghai) Biotechnology Co., Ltd.; the light stabilizer is 2,4-di-tert-butylphenol, with a CAS number of 96-76-4, (molecular weight: 206.32, purity ≥98%, light yellow crystal, melting point 53 - 56 °C), purchased from Shanghai Macklin Biochemical Co., Ltd.

[0050] The antioxidant in Example 4 is 4,4'-thiobis(6-tert-butyl-3-methylphenol), with a CAS number of 96-69-5, (molecular weight: 358.54, purity ≥95%, light yellow granules, melting point 160 - 165 °C), purchased from Shanghai Macklin Biochemical Co., Ltd.; the light stabilizer is 2-hydroxy-4-n-octyloxybenzophenone, with a CAS number of 1843-05-6, (molecular weight: 326.43, purity ≥97%, light yellow liquid, melting point 47 - 49 °C), purchased from Shanghai Macklin Biochemical Co., Ltd.

[0051] Example 1

[0052] An enhanced polyethylene recycled material modification composition, which includes 100 kg of polyethylene recycled material, 10 kg of chemical-based modifier, 1 kg of nano-enhancer, 3 kg of stabilizer, and 15 kg of functional filler.

[0053] In this example, the chemical-based modifier is PE-g-MAH, the nano-enhancer is carbon nanotubes, the stabilizer is a mixture of antioxidant β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid octadecyl ester and light stabilizer 2-(2'-hydroxy-5'-methylphenyl) benzotriazole mixed in a mass ratio of 2:1, and the functional filler is carbon fiber.

[0054] A preparation method of an enhanced polyethylene recycled material modification material, which uses the components in the above-mentioned enhanced polyethylene recycled material modification composition, and includes the following steps:

[0055] S1. Pretreat PE-g-MAH. Preheat 10 kg of PE-g-MAH at 110 °C to soften the material, and pre-stir it in a stirrer at 200 rpm to ensure the uniformity of its internal components, obtaining pretreated PE-g-MAH; mix the pretreated PE-g-MAH and 1 kg of carbon nanotubes at a stirring speed of 250 rpm and a temperature of 110 °C for 30 min to obtain a first mixture;

[0056] S2. Add the stabilizer composed of 2 kg of antioxidant and 1 kg of light stabilizer to the first mixture, and mix it at a stirring speed of 320 rpm and a temperature of 120 °C for 20 min to obtain a second mixture;

[0057] S3. Add 100 kg of polyethylene recycled material to the second mixture, and mix it at a stirring speed of 380 rpm and a temperature of 150 °C for 15 min to obtain a third mixture;

[0058] S4. Add 15 kg of carbon fiber to the third mixture, and mix it at a stirring speed of 120 rpm and a temperature of 70 °C for 10 min to obtain an intermediate product;

[0059] S5. Perform extrusion molding on the intermediate product. The extrusion temperature is 160 °C, the head pressure is 10 MPa, the screw speed is 100 rpm, the material stays in the mold for 30 seconds, and is shaped by water cooling at 20 °C. An enhanced polyethylene recycled material modification material is obtained.

[0060] Example 2

[0061] An enhanced polyethylene recycled material modification composition, the modification composition comprising 100 kg of polyethylene recycled material, 12 kg of chemical base modifier, 1.2 kg of nano-enhancer, 3.75 kg of stabilizer, and 13 kg of functional filler.

[0062] In this embodiment, the chemical base modifier is EVA, the nano-enhancer is graphene, the stabilizer is a mixture of antioxidant 4,4'-thiobis(6-tert-butyl-3-methylphenol) and light stabilizer 2-hydroxy-4-n-octyloxybenzophenone mixed in a mass ratio of 2:1, and the functional filler is glass fiber.

[0063] A preparation method of an enhanced polyethylene recycled material modification material, the preparation method being carried out using the components in the above-mentioned enhanced polyethylene recycled material modification composition, and comprising the following steps:

[0064] S1. Pretreat EVA. Preheat 12 kg of EVA at 85 °C to soften the material, and perform pre-stirring in a stirrer at 220 rpm to ensure the uniformity of its internal components, obtaining pretreated EVA;

[0065] Mix the pretreated EVA and 1.2 kg of graphene at a stirring speed of 230 rpm and a temperature of 110 °C for 35 min, obtaining a first mixture;

[0066] S2. Add 100 kg of polyethylene recycled material to the first mixture, and mix at a stirring speed of 300 rpm and a temperature of 130 °C for 25 min, obtaining a second mixture;

[0067] S3. Add the stabilizer composed of 2.5 kg of antioxidant and 1.25 kg of light stabilizer to the second mixture, and mix at a stirring speed of 350 rpm and a temperature of 150 °C for 20 min, obtaining a third mixture;

[0068] S4. Add 13 kg of glass fiber to the third mixture, and mix at a stirring speed of 100 rpm and a temperature of 65 °C for 8 min, obtaining an intermediate product;

[0069] S5. Perform extrusion molding on the intermediate product, with an extrusion temperature of 170 °C, a head pressure of 12 MPa, a screw speed of 150 rpm, the material staying in the mold for 30 seconds, and being shaped by water cooling at 20 °C. An enhanced polyethylene recycled material modification material is obtained.

[0070] Example 3

[0071] An enhanced polyethylene recycled material modification composition, which includes 100 kg of polyethylene recycled material, 8 kg of chemical-based modifier, 0.8 kg of nano-enhancer, 5.1 kg of stabilizer, and 10 kg of functional filler.

[0072] In this embodiment, the chemical-based modifier is PE-g-MAH, the nano-enhancer is graphene, the stabilizer is a mixture of antioxidant tris[2,4-di-tert-butylphenyl]phosphite and light stabilizer 2,4-di-tert-butylphenol mixed in a mass ratio of 3:2.1, and the functional filler is glass fiber.

[0073] A preparation method of an enhanced polyethylene recycled material modification material, which uses the components in the above-mentioned enhanced polyethylene recycled material modification composition, and includes the following steps:

[0074] S1. Pretreat PE-g-MAH. Preheat 8 kg of PE-g-MAH at 90 °C to soften the material, and pre-stir it at 240 rpm in a stirrer to ensure the uniformity of its internal components, obtaining the pretreated PE-g-MAH; mix the pretreated PE-g-MAH and 0.8 kg of graphene at a stirring speed of 220 rpm and a temperature of 100 °C for 30 min, obtaining the first mixture;

[0075] S2. Add 100 kg of polyethylene recycled material to the first mixture, and mix it at a stirring speed of 340 rpm and a temperature of 140 °C for 20 min, obtaining the second mixture;

[0076] S3. Add the stabilizer composed of 3 kg of antioxidant and 2.1 kg of light stabilizer to the second mixture, and mix it at a stirring speed of 390 rpm and a temperature of 150 °C for 10 min, obtaining the third mixture;

[0077] S4. Add 10 kg of glass fiber to the third mixture, and mix it at a stirring speed of 130 rpm and a temperature of 75 °C for 10 min, obtaining the intermediate product;

[0078] S5. Perform extrusion molding on the intermediate product, with an extrusion temperature of 180 °C, a head pressure of 10 MPa, a screw speed of 150 rpm, the material staying in the mold for 30 seconds, and shaping it by water cooling at 20 °C. Obtain the enhanced polyethylene recycled material modification material.

[0079] Example 4

[0080] An enhanced polyethylene recycled material modification composition, which includes 100 kg of polyethylene recycled material, 15 kg of chemical-based modifier, 1.5 kg of nano-enhancer, 3 kg of stabilizer, and 20 parts of functional filler.

[0081] In this embodiment, the chemical group modifier is EVA, the nano-enhancer is nano-silica, the stabilizer is antioxidant 4,4'-thiobis(6-tert-butyl-3-methylphenol), and the light stabilizer is a mixture of 2-hydroxy-4-n-octyloxybenzophenone and antioxidant 4,4'-thiobis(6-tert-butyl-3-methylphenol) in a mass ratio of 2:1, and the functional filler is glass fiber.

[0082] A preparation method of a modified material for recycled enhanced polyethylene uses the components in the above-mentioned modified composition of recycled enhanced polyethylene, and includes the following steps:

[0083] S1. Pretreat the EVA. Preheat 15 kg of EVA at 95 °C to soften the material, and pre-stir it in a stirrer at 240 rpm to ensure the uniformity of its internal components, obtaining the pretreated EVA; mix the pretreated EVA and 1.5 kg of nano-silica at a stirring speed of 240 rpm and a temperature of 100 °C for 40 min to obtain the first mixture;

[0084] S2. Add 100 kg of recycled polyethylene to the first mixture, and mix it at a stirring speed of 310 rpm and a temperature of 140 °C for 25 min to obtain the second mixture;

[0085] S3. Add the stabilizer composed of 2 kg of antioxidant and 1 kg of light stabilizer to the second mixture, and mix it at a stirring speed of 360 rpm and a temperature of 150 °C for 20 min to obtain the third mixture;

[0086] S4. Add 20 kg of glass fiber to the third mixture, and mix it at a stirring speed of 110 rpm and a temperature of 80 °C for 12 min to obtain an intermediate product;

[0087] S5. Perform extrusion molding on the intermediate product, with an extrusion temperature of 170 °C, a head pressure of 8 MPa, a screw speed of 120 rpm, the material staying in the mold for 30 seconds, and shaping it by water cooling at 20 °C. Obtain the modified material for recycled enhanced polyethylene.

[0088] Comparative Example 1

[0089] Compared with Example 1, most of them are the same, except that the nano-enhancer (carbon nanotubes) is not added. It is used to verify the influence of the nano-enhancer (carbon nanotubes) on the material properties.

[0090] Comparative Example 2

[0091] Compared with Example 2, most of them are the same, except that the chemical group modifier (EVA) is not added. It is used to verify the influence of the chemical group modifier (EVA) on the material properties.

[0092] Comparative Example 3

[0093] Compared with Example 3, most of them are the same, except that the addition amount of the nano-enhancer (graphene) is reduced to 0.1 kg. It is used to verify the influence of the addition amount of the nano-enhancer (graphene) on the material properties.

[0094] Comparative Example 4

[0095] Compared with Example 4, most of them are the same, except that no stabilizer is added. It is used to verify the influence of the stabilizer on the material properties.

[0096] Comparative Example 5

[0097] Compared with Example 1, most of them are the same, except that the functional filler (carbon fiber) is replaced with untreated ordinary filler (talc powder) to verify the influence of the functional filler (carbon fiber) on the material properties.

[0098] Comparative Example 6

[0099] Compared with Example 1, most of them are the same, except that the carbon nanotubes of the nano-enhancer are replaced with nano-clay (montmorillonite).

[0100] Comparative Example 7

[0101] Compared with Example 2, most of them are the same, except that the EVA of the chemical base modifier is replaced with styrene-ethylene-butene-styrene copolymer (SEBS).

[0102] Comparative Example 8

[0103] Compared with Example 1, most of them are the same, except that no functional filler (carbon fiber) is added to compare and verify the influence of the functional filler (carbon fiber) on the material properties.

[0104] Performance Test and Data Analysis:

[0105] In order to evaluate the properties of the enhanced polyethylene recycled material modified materials prepared in the examples and comparative examples of the present invention, the following performance tests were carried out:

[0106] Tensile Strength Test: According to the GB / T 1040 standard, it was tested using a universal material testing machine to obtain the tensile strength.

[0107] Flexural Strength Test: According to the GB / T 9341 standard, it was tested using a three-point bending testing machine to obtain the flexural strength.

[0108] Impact Strength Test: According to the GB / T 1843 standard, it was tested using a simply supported beam impact testing machine to obtain the impact strength.

[0109] Impurity point detection: By visually inspecting and counting the number of impurity points per unit area, and using a microscope for auxiliary observation, the number of impurity points is obtained.

[0110] Elongation at break: It refers to the percentage increase in the length of a material during the stretching process from the start of stretching to fracture. The calculation formula for elongation at break is:

[0111] Elongation at break (%) = [(L k - L0) / L0] × 100%

[0112] Where:

[0113] L k is the gauge length after fracture (mm).

[0114] L0 is the gauge length before fracture (mm).

[0115] During calculation, for those with elongation at break less than 5%, it is accurate to 0.1%; for those greater than or equal to 5%, it is accurate to 1%. The final result takes the arithmetic mean of the calculation data of no less than 3 specimens.

[0116] Table 1 shows the performance test data sheets of the modified materials of enhanced polyethylene recycled materials in Examples 1 - 4 and Comparative Examples 1 - 8.

[0117] Table 1 Performance Test Data Sheets of the Modified Materials of Enhanced Polyethylene Recycled Materials in Examples 1 - 4 and Comparative Examples 1 - 8

[0118]

[0119] As can be seen from Table 1, the modified materials of enhanced polyethylene recycled materials prepared in Examples 1 - 4 are significantly superior to the comparative examples in terms of tensile strength, flexural strength, impact strength, and elongation at break. This proves that the modified composition and materials of the enhanced polyethylene recycled materials of the present invention effectively improve the mechanical properties of polyethylene recycled materials. Moreover, the impurity points of the modified materials of enhanced polyethylene recycled materials in Examples 1 - 4 are significantly fewer than those of the comparative examples, indicating that the present invention can more effectively reduce impurities and improve the material quality.

[0120] Functions of chemical base modifiers and nano - reinforcing materials:

[0121] The comparison between Comparative Example 1 (without nano - reinforcing agent), Comparative Example 6, and Example 1 shows that the addition of nano - reinforcing agent significantly improves the tensile strength and flexural strength of the material. The material properties of Example 1 of the present invention have a tensile strength of 25 MPa, a flexural strength of 14 MPa, an impact strength of 50 KJ / m 2 , an elongation at break of 451%, and only 4 impurity points per m 2, the comparison ratios of 1 (without nano-enhancer) are increased by 47%, 55% and 39% respectively. The tensile strength of Example 1 using carbon nanotubes as nano-enhancer is 25 MPa, which is significantly higher than that of Comparative Example 6 (19 MPa) using nano-clay. Among them, the effect of carbon nanotubes is better than that of nano-clay (montmorillonite). The reason is that the microstructure of carbon nanotubes endows the advantage of high aspect ratio, which can construct an effective reinforcement network and disperse stress; its excellent mechanical properties can efficiently transfer external force; and it has good interfacial compatibility with the matrix, and the stress transfer is smooth. Specifically explained as: This is mainly attributed to the unique structural and performance advantages of carbon nanotubes. Carbon nanotubes have an extremely high aspect ratio and excellent mechanical properties. Their tubular structure can form a three-dimensional network reinforcement system in the polyethylene matrix, effectively transfer stress and improve the rigidity and deformation resistance of the material. In addition, the surface chemical activity of carbon nanotubes is relatively high. After chemical modification or physical dispersion treatment, it can better form an interfacial bond with the polyethylene matrix and chemical base modifier, reduce the agglomeration phenomenon, and thus significantly improve the uniformity of the composite material. In contrast, nano-clay has a layered silicate structure, with poor dispersion of its lamellae, easy to cause stress concentration due to stacking or agglomeration, and its reinforcement efficiency is limited by the low aspect ratio and insufficient interfacial compatibility, ultimately resulting in a limited increase in mechanical properties.

[0122] The comparison between Comparative Example 2 (without chemical base modifier), Comparative Example 7 and Example 2 shows that the chemical base modifier plays a key role in improving the overall performance of the material and promoting the dispersion of nano-enhancer. Among them, the effect of EVA is better than that of SEBS, because the polar structure of EVA improves the compatibility with the matrix and the dispersion of nano-enhancer, can achieve the balance of toughening and strengthening, and also optimizes the processing performance, while SEBS has weak polarity, poor strengthening effect and poor processing performance. Specifically explained as: As shown by the comparison between Example 2 and Comparative Example 7, the impact strength of Example 2 using EVA as chemical base modifier reaches 51 KJ / m 2 , which is significantly higher than that of Comparative Example 7 (44 KJ / m 2)。EVA (ethylene-vinyl acetate copolymer) contains polar vinyl acetate groups in its molecular chain, which can form hydrogen bonds or dipole interactions with recycled polyethylene materials, enhancing interfacial compatibility and promoting the uniform dispersion of nano-reinforcements (such as graphene). In addition, the introduction of EVA can effectively improve the flexibility of polyethylene molecular chains and enhance the impact resistance of the material. Although SEBS (styrene-ethylene-butene-styrene copolymer) is an elastomer, its non-polar styrene-butene segments have poor compatibility with polyethylene, resulting in weak interfacial bonding force. Moreover, the microphase separation structure of SEBS may hinder the uniform dispersion of nano-reinforcements, leading to an increase in internal defects of the material and ultimately limiting the improvement of mechanical properties. Experimental data show that EVA has significant advantages in optimizing interfacial bonding and dispersibility, making it more suitable for the efficient modification of recycled polyethylene materials. Comparing Comparative Example 2 (without chemical-based modifier) with Example 2, the absence of the chemical-based modifier led to a 50% decrease in tensile strength (12 MPa vs 24 MPa) and a 10-fold increase in impurity points (30 per m 2 vs 3 per m 2 ), indicating that the synergistic effect of the chemical-based modifier and nano-reinforcement significantly optimized interfacial compatibility and dispersibility.

[0123] Effect of nano-reinforcement addition amount:

[0124] The comparison between Comparative Example 3 and Example 3 shows that reducing the addition amount of nano-reinforcement will lead to a decline in material properties. However, even when the addition amount is relatively low (such as 0.1 kg), it can still improve material properties to a certain extent.

[0125] Role of stabilizer:

[0126] The comparison between Comparative Example 4 (without stabilizer) and Example 1 shows that although the impact strength (48 KJ / m 2 ) and elongation at break (400%) of Comparative Example 4 (without stabilizer) are close to those of Example 1, the retention rate of flexural strength after hygrothermal aging decreased by 30%, proving that the synergistic effect of the stabilizer and functional filler is crucial for long-term weather resistance. The addition of the stabilizer has a positive impact on the thermal stability and light stability of the material, although the improvement effect may not be as significant as that of chemical-based modifiers and nano-reinforcing materials.

[0127] Effect of functional filler:

[0128] The comparison between Comparative Example 5, Comparative Example 8 and Example 1 shows that there are 4 impurity points per m in Example 1 2 compared with 15 impurity points per m in Comparative Example 5 (replaced with ordinary filler talc powder) 2It was reduced by 73%. The elongation at break of Example 1 was 451%, which was 42% higher than 318% of Comparative Example 8 (without functional filler). The selection of functional filler has an important impact on the material properties. Ordinary untreated fillers (talc powder) cannot provide the same strengthening effect as functional fillers.

[0129] In summary, the present invention provides an enhanced polyethylene recycled material modified composition, material, its preparation method and application. By introducing chemical base modifiers and nano-enhancers, the mechanical properties and heat resistance of polyethylene recycled materials are significantly improved. The performance test results show that the modified materials prepared with the modified composition of the examples are superior to the comparative examples in terms of tensile strength, flexural strength, impact strength and elongation at break. In addition, the preparation method of the present invention can effectively reduce the number of impurity points and improve the material quality. Therefore, the present invention has broad application prospects and important practical value in the field of modification and utilization of polyethylene recycled materials.

[0130] Although the present invention has been described in detail above with general descriptions, specific embodiments and experiments, on the basis of the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. An enhanced polyethylene recycled material modified composition, characterized in that, The modified composition includes the following components: polyethylene recycled material, chemical-based modifier, nano-enhancer, stabilizer, functional filler; The chemical-based modifier includes polyethylene grafted maleic anhydride, ethylene-vinyl acetate copolymer or polymethyl methacrylate; The nano-enhancing material includes carbon nanotubes, graphene or nano-silica; The functional filler includes carbon fiber, glass fiber or nano-clay.

2. An enhanced polyethylene recycled material modified composition according to claim 1, characterized in that, By mass, the modified composition includes 100 parts of polyethylene recycled material, 2 - 20 parts of chemical-based modifier, 0.1 - 2 parts of nano-enhancer, 2 - 6 parts of stabilizer, and 5 - 30 parts of functional filler.

3. An enhanced polyethylene recycled material modified composition according to claim 1, characterized in that, The stabilizer is a combination of antioxidant and light stabilizer with a mass ratio of 1:0.5 - 1; The antioxidant includes octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 4,4'-thiobis(6-tert-butyl-3-methylphenol), tris(2,4-di-tert-butylphenyl) phosphite; The light stabilizer includes 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-hydroxy-4-n-octyloxybenzophenone, 2,4-di-tert-butylphenol.

4. A preparation method of a modified material for enhanced polyethylene recycled material, characterized in that, The preparation method is carried out with the components in an enhanced polyethylene recycled material modified composition as described in any one of claims 1 - 3, and includes the following steps: S1. First mix the chemical-based modifier and the nano-enhancer to obtain a first mixture; S2. Add the stabilizer to the first mixture for a second mixing to obtain a second mixture; S3. Add the polyethylene recycled material to the second mixture for a third mixing to obtain a third mixture; S4. Add the functional filler to the third mixture for a fourth mixing to obtain an intermediate product; S5. Subject the intermediate product to extrusion molding to obtain an enhanced polyethylene recycled material modified material.

5. The preparation method of an enhanced polyethylene recycled material modification material according to claim 4, characterized in that, In step S1, the stirring rate of the first mixing is 200 - 250 rpm and the temperature is 80 - 110 °C.

6. The preparation method of an enhanced polyethylene recycled material modified material according to claim 4, characterized in that, In step S2, the stirring rate of the second mixing is 300 - 350 rpm and the temperature is 120 - 150 °C.

7. The preparation method of an enhanced polyethylene recycled material modification material according to claim 4, characterized in that, In step S3, the stirring rate of the third mixing is 350 - 400 rpm and the temperature is 120 - 150 °C.

8. The preparation method of an enhanced polyethylene recycled material modified material according to claim 4, characterized in that, In step S4, the stirring rate of the fourth mixing is 100 - 150 rpm and the temperature is 60 - 80 °C.

9. An enhanced polyethylene recycled material modification material, characterized in that, It is prepared by the preparation method as described in any one of claims 4 - 8.

10. Application of an enhanced polyethylene recycled material modified material as described in claim 9 in the field of enhanced plastic products.

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