A modified graphene-resin composite material and its preparation method

Abstract

This invention relates to the field of polymer materials technology and discloses a modified graphene-resin composite material and its preparation method. The invention involves melt-blending polystyrene resin, polyethylene terephthalate (PET), styrene copolymer, benzoate-modified graphene, and an antioxidant in a torque rheometer to obtain the modified graphene-resin composite material. The styrene copolymer improves the compatibility between PS and PET, which is beneficial for improving the mechanical properties of the composite material. The modified graphene contains benzoate groups, which improves the interfacial properties between graphene and polystyrene and PET, allowing graphene to be uniformly dispersed in the resin composite material, further improving the mechanical strength of the composite material, resulting in higher impact strength, tensile strength, and flexural strength.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a modified graphene-resin composite material and its preparation method. Background Technology

[0002] Polystyrene is a common polymer resin material with good thermal insulation, strong electrical insulation, and high transparency, and is widely used in fibers, plastic sheets, and other applications. To improve the mechanical strength of polystyrene and expand its practical applications, it needs to be compounded with high-performance engineering plastics, such as polyethylene terephthalate, polycarbonate, polyphenylene ether, and nylon, to create composite plastics and fibers with even better performance.

[0003] Polyethylene terephthalate (PET) possesses excellent high-temperature resistance, impact resistance, and mechanical strength, making it widely used in plastics and fibers. However, PET has poor compatibility with polystyrene, resulting in composite materials with unsatisfactory mechanical properties. Patent CN109721868B discloses a method for manufacturing thermoplastic resin extruded foamed boards, involving the extrusion foaming of PET-based resins and polystyrene-based resins, yielding foamed boards with good thermal insulation properties. However, the foamed board material of this patent lacks good flexural strength and other mechanical properties.

[0004] The surface of graphene oxide contains abundant oxygen-containing functional groups such as hydroxyl groups, making it easy to modify with organic materials. Modified graphene exhibits excellent dispersibility and better interfacial properties with polymers such as polystyrene and polyethylene terephthalate, which can significantly improve the mechanical and other properties of the materials. Summary of the Invention

[0005] (a) Technical problem solved: The present invention solves the problem of poor compatibility between graphene, polystyrene and polyethylene terephthalate.

[0006] (II) Technical Solution: A method for preparing a modified graphene-resin composite material:

[0007] (1) Add styrene, bis(4-vinylbenzoate) and azobisisobutyronitrile to N,N-dimethylformamide, react in a nitrogen atmosphere, cool and filter, wash the product with ethanol, dry and obtain styrene copolymer.

[0008] (2) The polystyrene resin, polyethylene terephthalate, styrene copolymer, benzoate-modified graphene and antioxidant in the proportion of (75-90)g:(10-25)g:(1-4)g:(0.3-1.2)g:(0.2-0.4)g are mixed in a mixer and then melt-blended in a torque rheometer to obtain the modified graphene-resin composite material.

[0009] Furthermore, in (1), the ratio of styrene, bis(4-vinylbenzoic acid ethyl ester), and azobisisobutyronitrile is (80-90) g: (10-20) g: (3.8-5) g.

[0010] Furthermore, in (1), the reaction temperature is 65-80℃ and the reaction time is 7-10h.

[0011] Furthermore, in (2), the mixing temperature is 60-80℃ and the mixing time is 20-40min.

[0012] Furthermore, in (2), the melt blending temperature is 260-275℃ and the blending time is 6-8min.

[0013] Further, the preparation method of bis(4-vinylbenzoic acid ethyl ester) is as follows: 4-vinylbenzoic acid, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 4-dimethylaminopyridine are added to dichloromethane and stirred for 20-30 min. Then ethylene glycol is added, wherein the ratio of 4-vinylbenzoic acid, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 4-dimethylaminopyridine, and ethylene glycol is (3.8-4.6) g:(8-9) g:(8-10) g:1 g. The reaction is carried out for 24-36 h. After filtration, the filtrate is evaporated by rotary evaporation and separated by column chromatography to obtain bis(4-vinylbenzoic acid ethyl ester).

[0014] Furthermore, the preparation method of benzoate-modified graphene is as follows: graphene oxide and triethylamine are added to N,N-dimethylformamide, ultrasonically dispersed, and benzoyl chloride is added dropwise in an ice-water bath, wherein the ratio of graphene oxide, triethylamine and benzoyl chloride is 100g:(48-110)g:(60-150)g; the reaction is carried out at 15-25℃ for 18-36h, filtered, the product is washed with water and ethanol in sequence, and dried to obtain benzoate-modified graphene.

[0015] Furthermore, graphene-resin composite materials can also be processed into plastics, sheets, fibers, and other materials through injection molding, compression molding, spinning, and other processes.

[0016] (III) Beneficial technical effects: The present invention polymerizes styrene and bis(4-vinylbenzoic acid ethyl ester) containing two alkenyl groups to obtain a styrene copolymer with ethyl benzoate groups in the main chain; benzoyl chloride is used to esterify the hydroxyl groups on the surface of graphene oxide to obtain benzoate-modified graphene, which is then melt-blended with styrene copolymer, polystyrene resin and polyethylene terephthalate to obtain a modified graphene-resin composite material.

[0017] The styrene copolymer of the present invention contains a polystyrene molecular chain, and the main chain contains ethyl benzoate groups similar to polyethylene terephthalate, which enables the styrene copolymer to compatibilize polystyrene (PS) and polyethylene terephthalate (PET), thereby improving the compatibility between PS and PET and improving the mechanical properties of the composite material.

[0018] The modified graphene of this invention contains benzoic acid ester groups, which improves the interfacial properties between graphene and polystyrene and polyethylene terephthalate, allowing graphene to be uniformly dispersed in the resin composite material, further improving the mechanical strength of the composite material, and giving it higher impact strength, tensile strength and flexural strength.

[0019] The resin composite material of the present invention can also be processed into high-performance plastics, sheets, fibers and other materials through injection molding, compression molding, spinning and other processes. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0021] (1) Add 2g of graphene oxide and 0.96g of triethylamine to 150mL of N,N-dimethylformamide, disperse by ultrasonication, add 1.2g of benzoyl chloride dropwise in an ice-water bath, react at 20℃ for 18h, filter, wash the product with water and ethanol in sequence, dry, and obtain benzoate-modified graphene.

[0022] (2) Add 7.6 g of 4-vinylbenzoic acid, 16 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 20 g of 4-dimethylaminopyridine to 200 mL of dichloromethane, stir for 20 min, then add 2 g of ethylene glycol, react for 36 h, filter, evaporate the filtrate by rotary evaporation, and separate by column chromatography using a mixture of ethyl acetate and petroleum ether as the eluent to obtain bis(4-vinylbenzoate ethyl ester). The preparation reaction is as follows;

[0023] .

[0024] (3) Add 8.5g styrene, 1.5g bis(4-vinylbenzoate) and 0.45g azobisisobutyronitrile to 80mL N,N-dimethylformamide, heat to 70℃ in a nitrogen atmosphere, react for 10h, cool and filter, wash the product with ethanol, dry and obtain styrene copolymer.

[0025] (4) 900g of polystyrene resin, 100g of polyethylene terephthalate, 10g of styrene copolymer, 3g of benzoate-modified graphene and 4g of antioxidant 1076 were mixed in a mixer at 80°C for 20min, and then melt-blended in a torque rheometer at 260°C for 6min to obtain the modified graphene-resin composite material. Example 2

[0026] (1) Add 2g of graphene oxide and 2.2g of triethylamine to 200mL of N,N-dimethylformamide, disperse by ultrasonication, add 3g of benzoyl chloride dropwise in an ice-water bath, react at 15℃ for 36h, filter, wash the product with water and ethanol in sequence, dry, and obtain benzoate modified graphene.

[0027] (2) Add 9.2g of 4-vinylbenzoic acid, 18g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 16g of 4-dimethylaminopyridine to 300mL of dichloromethane, stir for 30min, then add 2g of ethylene glycol, react for 24h, filter, evaporate the filtrate by rotary evaporation, separate by column chromatography, and use a mixed solution of ethyl acetate and petroleum ether as the eluent to obtain bis(4-vinylbenzoic acid ethyl ester).

[0028] (3) Add 9g styrene, 1g bis(4-vinylbenzoate) and 0.5g azobisisobutyronitrile to 60mL N,N-dimethylformamide, heat to 65℃ in a nitrogen atmosphere, react for 10h, cool and filter, wash the product with ethanol, dry and obtain styrene copolymer.

[0029] (4) 850g of polystyrene resin, 150g of polyethylene terephthalate, 22g of styrene copolymer, 8g of benzoate-modified graphene, and 4g of antioxidant 1076 were mixed in a mixer at 60°C for 40min, and then melt-blended in a torque rheometer at 265°C for 8min to obtain the modified graphene-resin composite material. Example 3

[0030] (1) Add 2g of graphene oxide and 1.56g of triethylamine to 200mL of N,N-dimethylformamide, disperse by ultrasonication, add 2.3g of benzoyl chloride dropwise in an ice-water bath, react at 25℃ for 36h, filter, wash the product with water and ethanol in sequence, dry, and obtain benzoate modified graphene.

[0031] (2) Add 8g of styrene, 2g of bis(4-vinylbenzoate) (prepared according to the method of Example 1) and 0.38g of azobisisobutyronitrile to 80mL of N,N-dimethylformamide. Heat to 80℃ in a nitrogen atmosphere and react for 7h. After cooling, filter, wash the product with ethanol, and dry to obtain styrene copolymer.

[0032] (3) 750g of polystyrene resin, 250g of polyethylene terephthalate, 40g of styrene copolymer, 12g of benzoate-modified graphene, and 2g of antioxidant 1076 were mixed in a mixer at 80°C for 30min, and then melt-blended in a torque rheometer at 275°C for 8min to obtain the modified graphene-resin composite material.

[0033] Comparative Example 1

[0034] (1) 900g of polystyrene resin, 100g of polyethylene terephthalate, 10g of styrene copolymer (prepared according to the method of Example 1), 3g of graphene oxide and 4g of antioxidant 1076 were mixed in a mixer at 80°C for 20min, and then melt-blended in a torque rheometer at 260°C for 6min to obtain a graphene-resin composite material.

[0035] Comparative Example 2

[0036] (1) Add 2g of graphene oxide and 0.96g of triethylamine to 150mL of N,N-dimethylformamide, disperse by ultrasonication, add 1.2g of propionyl chloride dropwise in an ice-water bath, react at 20℃ for 18h, filter, wash the product with water and ethanol in sequence, dry, and obtain propionate-modified graphene.

[0037] (2) 900g of polystyrene resin, 100g of polyethylene terephthalate, 10g of styrene copolymer (prepared according to the method of Example 1), 3g of propionate-modified graphene, and 4g of antioxidant 1076 were mixed in a mixer at 80°C for 20min, and then melt-blended in a torque rheometer at 260°C for 6min to obtain a modified graphene-resin composite material.

[0038] Comparative Example 3

[0039] (1) 900g of polystyrene resin, 100g of polyethylene terephthalate, 3g of benzoate-modified graphene and 4g of antioxidant 1076 were mixed in a mixer at 80°C for 20min, and then melt-blended in a torque rheometer at 260°C for 6min to obtain the modified graphene-resin composite material.

[0040] Comparative Example 4

[0041] (1) Add 8.5g styrene, 1.5g ethylene glycol diacrylate and 0.45g azobisisobutyronitrile to 80mL N,N-dimethylformamide, heat to 70℃ in a nitrogen atmosphere, react for 10h, cool and filter, wash the product with ethanol, dry and obtain styrene copolymer.

[0042] (2) 900g of polystyrene resin, 100g of polyethylene terephthalate, 10g of styrene copolymer, 3g of benzoate-modified graphene (prepared according to the method of Example 1) and 4g of antioxidant 1076 were mixed in a mixer at 80°C for 20min, and then melt-blended in a torque rheometer at 260°C for 6min to obtain a modified graphene-resin composite material.

[0043] Comparative Example 5

[0044] (1) Add 8.5g styrene, 1.5g ethyl 4-vinylbenzoate and 0.45g azobisisobutyronitrile to 80mL N,N-dimethylformamide, heat to 70℃ in a nitrogen atmosphere, react for 10h, cool and filter, wash the product with ethanol, dry and obtain styrene copolymer.

[0045] (2) 900g of polystyrene resin, 100g of polyethylene terephthalate, 10g of styrene copolymer, 3g of benzoate-modified graphene (prepared according to the method of Example 1) and 4g of antioxidant 1076 were mixed in a mixer at 80°C for 20min, and then melt-blended in a torque rheometer at 260°C for 6min to obtain a modified graphene-resin composite material.

[0046] The composite material is hot-pressed into sheets using a flat vulcanizing machine at a temperature of 270°C and a pressure of 10 MPa.

[0047] Impact strength was tested according to the method specified in GB / T 1043.1-2008. Tensile properties were tested according to the method specified in GB / T 1040.1-2018. Flexural strength was tested according to the method specified in GB / T 9341-2008.

[0048] Table 1 Performance testing of composite materials

[0049]

[0050] In the polystyrene resin and polyethylene terephthalate resin composites prepared in each embodiment, styrene copolymer and benzoate-modified graphene were added. The styrene copolymer contains polystyrene molecular chains, and the main chain contains ethyl benzoate groups similar to polyethylene terephthalate. This allows the styrene copolymer to compatibilize polystyrene (PS) and polyethylene terephthalate (PET), improving the compatibility between PS and PET and thus enhancing the mechanical properties of the composite material. Furthermore, the modified graphene contains benzoate groups, which improves the interfacial properties between graphene and polystyrene and polyethylene terephthalate, allowing graphene to be uniformly dispersed in the resin composite material. This further enhances the mechanical strength of the composite material, resulting in higher impact strength, tensile strength, and flexural strength.

[0051] Compared with Example 1, the graphene oxide in Comparative Example 1 does not contain benzoic acid ester groups, resulting in poor interfacial properties with polystyrene and polyethylene terephthalate, leading to poor dispersibility of graphene oxide and lower mechanical properties of the resin composite material compared to Example 1.

[0052] Comparative Example 2 involved esterifying graphene oxide with propionyl chloride without introducing a benzene ring structure. This resulted in lower interfacial properties with polystyrene and polyethylene terephthalate, leading to poor dispersibility of graphene oxide and lower mechanical properties of the resin composite material compared to Example 1.

[0053] Comparative Example 3 did not include styrene copolymer, resulting in poor compatibility between polystyrene resin and polyethylene terephthalate, and the mechanical properties of the composite material were lower than those in Example 1.

[0054] Comparative Example 4 copolymerized conventional ethylene glycol diacrylate with styrene. The resulting styrene copolymer did not contain ethyl benzoate groups, which led to poor compatibilization effect of the styrene copolymer on PS and PET. The mechanical properties of the composite material were lower than those in Example 1.

[0055] Comparative Example 5 copolymerized conventional ethyl 4-vinylbenzoate (containing only one alkenyl group) with styrene. The resulting styrene copolymer contained ethyl benzoate groups only in the side chain, and its compatibilizing effect was lower than that of the styrene copolymer in Example 1, which contained ethyl benzoate groups in the main chain. As a result, the mechanical properties of the composite material were lower than those in Example 1.

[0056] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a modified graphene-resin composite material, characterized in that, The preparation method is as follows: (1) Add styrene, bis(4-vinylbenzoic acid) ethylene glycol ester and azobisisobutyronitrile to N,N-dimethylformamide, react in a nitrogen atmosphere, cool and filter, wash the product, dry and obtain styrene copolymer; (2) Polystyrene resin, polyethylene terephthalate, styrene copolymer, benzoate-modified graphene, and antioxidant in a ratio of (75-90)g:(10-25)g:(1-4)g:(0.3-1.2)g:(0.2-0.4)g are mixed in a mixer and then melt-blended in a torque rheometer to obtain a modified graphene-resin composite material; The preparation method of the benzoate-modified graphene is as follows: graphene oxide and triethylamine are added to N,N-dimethylformamide, ultrasonically dispersed, benzoyl chloride is added dropwise in an ice-water bath, and then reacted at 15-25℃ for 18-36h. The product is filtered, washed, and dried to obtain benzoate-modified graphene.

2. The method for preparing the modified graphene-resin composite material according to claim 1, characterized in that, In step (1), the ratio of styrene, bis(4-vinylbenzoic acid) glycol ester, and azobisisobutyronitrile is (80-90) g: (10-20) g: (3.8-5) g.

3. The method for preparing the modified graphene-resin composite material according to claim 1, characterized in that, The reaction temperature in step (1) is 65-80℃, and the reaction time is 7-10h.

4. The method for preparing the modified graphene-resin composite material according to claim 1, characterized in that, The mixing temperature in step (2) is 60-80℃ and the mixing time is 20-40min.

5. The method for preparing the modified graphene-resin composite material according to claim 1, characterized in that, The melting and blending temperature in step (2) is 260-275℃, and the blending time is 6-8 min.

6. The method for preparing the modified graphene-resin composite material according to claim 1, characterized in that, The preparation method of the bis(4-vinylbenzoic acid) ethylene glycol ester is as follows: 4-vinylbenzoic acid, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine are added to dichloromethane and stirred for 20-30 min. Then ethylene glycol is added and the reaction is carried out for 24-36 h. After filtration, the filtrate is evaporated by rotary evaporation and separated by column chromatography to obtain bis(4-vinylbenzoic acid) ethylene glycol ester.

7. The method for preparing the modified graphene-resin composite material according to claim 6, characterized in that, The ratio of 4-vinylbenzoic acid, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 4-dimethylaminopyridine, and ethylene glycol is (3.8-4.6) g: (8-9) g: (8-10) g: 1 g.

8. The method for preparing the modified graphene-resin composite material according to claim 1, characterized in that, The ratio of graphene oxide, triethylamine, and benzoyl chloride is 100g:(48-110)g:(60-150)g.

9. A modified graphene-resin composite material obtained by the preparation method according to any one of claims 1-8.

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