Modified graphene-resin composite material and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, and discloses a modified graphene-resin composite material and a preparation method thereof.The preparation method comprises the steps that polystyrene resin, polyethylene glycol terephthalate, a styrene copolymer, benzoate modified graphene and an antioxidant are subjected to melt blending in a torque rheometer; the modified graphene-resin composite material is obtained. The styrene copolymer improves the compatibility between PS and PET, and is beneficial to improving the mechanical properties of the composite material. The modified graphene contains benzoate groups, so that the interface performance between the graphene and polystyrene and polyethylene glycol terephthalate is improved, the graphene is uniformly dispersed in the resin composite material, the mechanical strength of the composite material is further improved, and the composite material has higher impact strength, tensile strength and bending strength.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to a modified graphene-resin composite material and a preparation method thereof. Background Art

[0002] Polystyrene is a common polymer resin material with excellent thermal and electrical insulation properties and high transparency, making it widely used in fibers, plastic sheets, and other applications. To improve the mechanical strength of polystyrene and expand its practical applications, it is necessary to compound polystyrene with high-performance engineering plastics such as polyethylene terephthalate, polycarbonate, polyphenylene ether, and nylon. This can produce composite plastics, fibers, and other materials with even better performance.

[0003] Polyethylene terephthalate (PET) has excellent high-temperature resistance, impact resistance, and mechanical strength, making it widely used in plastics, fibers, and other applications. However, PET and polystyrene have poor compatibility, and the resulting composite materials have poor mechanical properties. Patent No. CN109721868B discloses a method for manufacturing thermoplastic resin extrusion foaming sheets. The method involves extruding and foaming PET and polystyrene resins to produce foamed sheets with excellent thermal insulation properties. However, the foamed sheet material in this patent lacks good mechanical properties, such as flexural strength.

[0004] The surface of graphene oxide contains abundant oxygen-containing functional groups such as hydroxyl groups, which makes it easy to undergo surface organic modification. The modified graphene has excellent dispersibility and better interfacial properties with polymer materials such as polystyrene and polyethylene terephthalate, which can significantly improve the mechanical properties of the material. Summary of the Invention

[0005] (1) Technical problem to be solved: The present invention solves the problem of poor compatibility among graphene, polystyrene and polyethylene terephthalate.

[0006] (II) Technical Solution: A method for preparing a modified graphene-resin composite material: (1) Styrene, bis(ethyl 4-vinylbenzoate) and azobisisobutyronitrile were added to N,N-dimethylformamide and reacted in a nitrogen atmosphere. After cooling, the product was filtered, washed with ethanol and dried to obtain a styrene copolymer.

[0007] (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.

[0008] Furthermore, the ratio of styrene, bis(ethyl 4-vinylbenzoate), and azobisisobutyronitrile in (1) is (80-90) g: (10-20) g: (3.8-5) g.

[0009] Furthermore, the reaction temperature in (1) is 65-80°C, and the reaction time is 7-10 hours.

[0010] Furthermore, the mixing temperature in (2) is 60-80°C, and the mixing time is 20-40 minutes.

[0011] Furthermore, the melt blending temperature in (2) is 260-275°C, and the blending time is 6-8 minutes.

[0012] Furthermore, 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, stirred for 20-30 minutes, and 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 hours, and the filtrate is rotary evaporated after filtering and separated by column chromatography to obtain bis(4-vinylbenzoic acid ethyl ester).

[0013] 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°C for 18-36h, filtered, and the product is washed with water and ethanol in sequence, and dried to obtain benzoate-modified graphene.

[0014] Furthermore, graphene-resin composite materials can also be made into plastics, plates, fibers and other materials through injection molding, molding, spinning and other processes.

[0015] (III) Beneficial technical effects: The present invention polymerizes styrene and bis(4-vinylethylbenzoate) containing two alkenyl groups to obtain a styrene copolymer having an ethylbenzoate group in the main chain; benzoyl chloride is used to carry out an esterification reaction with the hydroxyl groups on the surface of graphene oxide to obtain benzoate-modified graphene, which is then melt-blended with a styrene copolymer, a polystyrene resin, and polyethylene terephthalate to obtain a modified graphene-resin composite material.

[0016] The styrene copolymer of the present invention contains a polystyrene molecular chain and contains an ethyl benzoate group similar to polyethylene terephthalate in the main chain, so that the styrene copolymer can compatibilize polystyrene (PS) and polyethylene terephthalate (PET), thereby improving the compatibility between PS and PET and facilitating the improvement of the mechanical properties of the composite material.

[0017] The modified graphene of the present invention contains benzoate groups, which improves the interface performance between graphene and polystyrene and polyethylene terephthalate, makes the graphene uniformly dispersed in the resin composite material, further improves the mechanical strength of the composite material, and has higher impact strength, tensile strength and bending strength.

[0018] The resin composite material of the present invention can also be made into plastics, plates, fibers and other materials with excellent performance through injection molding, molding, spinning and other processes. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example 1

[0020] (1) Add 2 g of graphene oxide and 0.96 g of triethylamine to 150 mL of N,N-dimethylformamide, disperse by ultrasonication, add 1.2 g of benzoyl chloride dropwise in an ice-water bath, react at 20 °C for 18 h, filter, wash the product with water and ethanol in turn, and dry to obtain benzoate-modified graphene.

[0021] (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 and react for 36 h. After filtering, the filtrate is rotary evaporated and separated by column chromatography using a mixed solution of ethyl acetate and petroleum ether as the eluent to obtain bis(4-vinylbenzoic acid ethyl ester). The preparation reaction is as follows; .

[0022] (3) Add 8.5 g of styrene, 1.5 g of bis(ethyl 4-vinylbenzoate), and 0.45 g of azobisisobutyronitrile to 80 mL of N,N-dimethylformamide, heat to 70 °C in a nitrogen atmosphere, react for 10 h, cool, filter, wash the product with ethanol, and dry to obtain a styrene copolymer.

[0023] (4) 900 g of polystyrene resin, 100 g of polyethylene terephthalate, 10 g of styrene copolymer, 3 g of benzoate-modified graphene, and 4 g of antioxidant 1076 were mixed in a mixer at 80 °C for 20 min, and then melt-blended in a torque rheometer at 260 °C for 6 min to obtain a modified graphene-resin composite material. Example 2

[0024] (1) Add 2 g of graphene oxide and 2.2 g of triethylamine to 200 mL of N,N-dimethylformamide, disperse by ultrasonication, add 3 g of benzoyl chloride dropwise in an ice-water bath, react at 15 °C for 36 h, filter, wash the product with water and ethanol in turn, and dry to obtain benzoate-modified graphene.

[0025] (2) Add 9.2 g of 4-vinylbenzoic acid, 18 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 16 g of 4-dimethylaminopyridine to 300 mL of dichloromethane and stir for 30 min. Then add 2 g of ethylene glycol and react for 24 h. After filtering, the filtrate is rotary evaporated and separated by column chromatography using a mixed solution of ethyl acetate and petroleum ether as the eluent to obtain bis(ethyl 4-vinylbenzoate).

[0026] (3) Add 9 g of styrene, 1 g of ethyl bis(4-vinylbenzoate), and 0.5 g of azobisisobutyronitrile to 60 mL of N,N-dimethylformamide, heat to 65 °C in a nitrogen atmosphere, react for 10 h, cool, filter, wash the product with ethanol, and dry to obtain a styrene copolymer.

[0027] (4) 850 g of polystyrene resin, 150 g of polyethylene terephthalate, 22 g of styrene copolymer, 8 g of benzoate-modified graphene, and 4 g of antioxidant 1076 were mixed in a mixer at 60 °C for 40 min, and then melt-blended in a torque rheometer at 265 °C for 8 min to obtain a modified graphene-resin composite material. Example 3

[0028] (1) Add 2 g of graphene oxide and 1.56 g of triethylamine to 200 mL of N,N-dimethylformamide, disperse by ultrasonication, add 2.3 g of benzoyl chloride dropwise in an ice-water bath, react at 25 °C for 36 h, filter, wash the product with water and ethanol in sequence, and dry to obtain benzoate-modified graphene.

[0029] (2) To 80 mL of N,N-dimethylformamide were added 8 g of styrene, 2 g of bis(ethyl 4-vinylbenzoate) (prepared according to the method of Example 1), and 0.38 g of azobisisobutyronitrile. The mixture was heated to 80°C in a nitrogen atmosphere and reacted for 7 h. After cooling, the mixture was filtered, washed with ethanol, and dried to obtain a styrene copolymer.

[0030] (3) 750 g of polystyrene resin, 250 g of polyethylene terephthalate, 40 g of styrene copolymer, 12 g of benzoate-modified graphene, and 2 g of antioxidant 1076 were mixed in a mixer at 80 °C for 30 min, and then melt-blended in a torque rheometer at 275 °C for 8 min to obtain a modified graphene-resin composite material.

[0031] Comparative Example 1 (1) 900 g of polystyrene resin, 100 g of polyethylene terephthalate, 10 g of styrene copolymer (prepared according to the method of Example 1), 3 g of graphene oxide, and 4 g of antioxidant 1076 were mixed in a mixer at 80 °C for 20 min, and then melt-blended in a torque rheometer at 260 °C for 6 min to obtain a graphene-resin composite material.

[0032] Comparative Example 2 (1) Add 2 g of graphene oxide and 0.96 g of triethylamine to 150 mL of N,N-dimethylformamide, disperse by ultrasonication, add 1.2 g of propionyl chloride dropwise in an ice-water bath, react at 20 °C for 18 h, filter, wash the product with water and ethanol in turn, and dry to obtain propionate-modified graphene.

[0033] (2) 900 g of polystyrene resin, 100 g of polyethylene terephthalate, 10 g of styrene copolymer (prepared according to the method of Example 1), 3 g of propionate-modified graphene, and 4 g of antioxidant 1076 were mixed in a mixer at 80 °C for 20 min, and then melt-blended in a torque rheometer at 260 °C for 6 min to obtain a modified graphene-resin composite material.

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

[0035] Comparative Example 4 (1) Add 8.5 g of styrene, 1.5 g of ethylene glycol diacrylate, and 0.45 g of azobisisobutyronitrile to 80 mL of N,N-dimethylformamide, heat to 70 °C in a nitrogen atmosphere, react for 10 h, cool, filter, wash the product with ethanol, and dry to obtain a styrene copolymer.

[0036] (2) 900 g of polystyrene resin, 100 g of polyethylene terephthalate, 10 g of styrene copolymer, 3 g of benzoate-modified graphene (prepared according to the method of Example 1), and 4 g of antioxidant 1076 were mixed in a mixer at 80 °C for 20 min, and then melt-blended in a torque rheometer at 260 °C for 6 min to obtain a modified graphene-resin composite material.

[0037] Comparative Example 5 (1) Add 8.5 g of styrene, 1.5 g of ethyl 4-vinylbenzoate, and 0.45 g of azobisisobutyronitrile to 80 mL of N,N-dimethylformamide. Heat to 70 °C in a nitrogen atmosphere and react for 10 h. After cooling, filter and wash the product with ethanol and dry it to obtain a styrene copolymer.

[0038] (2) 900 g of polystyrene resin, 100 g of polyethylene terephthalate, 10 g of styrene copolymer, 3 g of benzoate-modified graphene (prepared according to the method of Example 1), and 4 g of antioxidant 1076 were mixed in a mixer at 80 °C for 20 min, and then melt-blended in a torque rheometer at 260 °C for 6 min to obtain a modified graphene-resin composite material.

[0039] The composite material was hot-pressed into a sheet using a flat vulcanizer at a temperature of 270°C and a pressure of 10 MPa.

[0040] Impact strength is tested according to the method specified in GB / T 1043.1-2008. Tensile properties are tested according to the method specified in GB / T 1040.1-2018. Flexural strength is tested according to the method specified in GB T 9341-2008.

[0041] Table 1 Performance test of composite materials

[0042] Styrene copolymer and benzoate-modified graphene are added to the resin composite materials of polystyrene resin and polyethylene terephthalate prepared in each embodiment. The styrene copolymer contains a polystyrene molecular chain, and the main chain contains an ethyl benzoate group similar to polyethylene terephthalate, so that the styrene copolymer can compatibilize polystyrene PS and polyethylene terephthalate PET, improve the compatibility between PS and PET, and help improve the mechanical properties of the composite material. In addition, the modified graphene contains benzoate groups, which improves the interface performance between graphene and polystyrene and polyethylene terephthalate, so that the graphene is uniformly dispersed in the resin composite material, further improving the mechanical strength of the composite material, and having higher impact strength, tensile strength and flexural strength.

[0043] Compared with Example 1, the graphene oxide in Comparative Example 1 does not contain benzoate groups, and the interface performance between it and polystyrene and polyethylene terephthalate is very poor, resulting in poor dispersion of graphene oxide and lower mechanical properties of the resin composite material than Example 1.

[0044] In Comparative Example 2, graphene oxide was esterified with propionyl chloride without introducing a benzene ring structure. As a result, the interfacial properties between graphene oxide and polystyrene and polyethylene terephthalate were low, resulting in poor dispersion of graphene oxide and lower mechanical properties of the resin composite material than those in Example 1.

[0045] In Comparative Example 3, no styrene copolymer was added, the compatibility between the polystyrene resin and the polyethylene terephthalate was poor, and the mechanical properties of the composite material were lower than those in Example 1.

[0046] In Comparative Example 4, conventional ethylene glycol diacrylate was copolymerized with styrene. The prepared styrene copolymer did not contain ethyl benzoate groups, resulting in poor compatibilization effect of the styrene copolymer on PS and PET, and the mechanical properties of the composite material were lower than those in Example 1.

[0047] In Comparative Example 5, conventional 4-vinyl-ethyl benzoate (containing only one alkenyl group) is copolymerized with styrene. The prepared styrene copolymer contains ethyl benzoate groups only in the side chains. Its compatibilization effect is lower than that of the styrene copolymer containing ethyl benzoate groups in the main chain in Example 1, resulting in the mechanical properties of the composite material being lower than those in Example 1.

[0048] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall 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(ethyl 4-vinylbenzoate) and azobisisobutyronitrile to N,N-dimethylformamide, react in a nitrogen atmosphere, cool and filter, wash the product, and dry to obtain a 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.

2. The method for preparing a modified graphene-resin composite material according to claim 1, wherein The ratio of styrene, bis(ethyl 4-vinylbenzoate) and azobisisobutyronitrile in (1) 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, wherein The reaction temperature in (1) is 65-80°C, and the reaction time is 7-10 hours.

4. The method for preparing the modified graphene-resin composite material according to claim 1, wherein The mixing temperature in (2) is 60-80°C, and the mixing time is 20-40 minutes.

5. The method for preparing the modified graphene-resin composite material according to claim 1, wherein The temperature of the melt blending in (2) is 260-275°C, and the blending time is 6-8 minutes.

6. The method for preparing the modified graphene-resin composite material according to claim 1, wherein The preparation method of bis(ethyl 4-vinylbenzoate) comprises: adding 4-vinylbenzoic acid, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and 4-dimethylaminopyridine to dichloromethane, stirring for 20-30 minutes, then adding ethylene glycol, reacting for 24-36 hours, filtering, rotary evaporating the filtrate, and separating by column chromatography to obtain bis(ethyl 4-vinylbenzoate).

7. The method for preparing the modified graphene-resin composite material according to claim 6, wherein: The ratio of the 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, wherein The preparation method of the benzoate-modified graphene comprises: adding graphene oxide and triethylamine to N,N-dimethylformamide, ultrasonically dispersing, dropwise adding benzoyl chloride in an ice-water bath, reacting at 15-25° C. for 18-36 hours, filtering, washing the product, and drying to obtain the benzoate-modified graphene.

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

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

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