High-conductivity composite material for enhancing silicone rubber through graphene nanosheets

Abstract

The invention discloses a high-conductivity composite material with silicone rubber reinforced by graphene nanosheets. A preparation method of the composite material comprises the following steps: S1, hydroxyl-terminated polydimethylsiloxane is selected as a silicone rubber matrix, and modified graphene nanosheets are selected as a reinforcing material; s2, modifying the graphene nanosheets; s3, the modified graphene nanosheets are dispersed; s4, mixing the composite material; s5, adding a cross-linking agent and a catalyst; and S6, forming and vulcanizing: injecting the uniformly mixed composite material into a mold and vulcanizing. The composite material prepared by the invention has high conductivity, excellent mechanical properties and good thermal stability, and is suitable for the fields of electronic elements, conductive adhesives and the like.

Description

Technical Field

[0001] The invention relates to the field of preparation of a highly conductive composite material, and more particularly to a highly conductive composite material of silicone rubber reinforced by graphene nanosheets. Background Art

[0002] With the development of miniaturization, high performance and intelligence of electronic equipment, higher and higher requirements are placed on the conductivity, mechanical properties and environmental adaptability of materials. Silicone rubber is widely used in the insulation, sealing and protection of electronic components due to its excellent heat resistance, weather resistance and elasticity. However, traditional silicone rubber has poor conductivity and cannot meet the demand for conductive materials in some high-performance electronic devices.

[0003] Graphene, a two-dimensional material composed of carbon atoms, has become a research hotspot in the field of materials science in recent years due to its unique electrical, mechanical and thermal properties. Graphene has extremely high conductivity, excellent mechanical properties and a large specific surface area, making it an ideal choice for enhancing the conductivity of composite materials. By introducing graphene nanosheets into a silicone rubber matrix, it is expected to form a composite material with both high conductivity and good mechanical properties. This composite material can be used not only in electronic devices, but also in sensors, conductive adhesives and other fields, and has broad application prospects.

[0004] However, in the actual preparation process, the uniform dispersion of graphene nanosheets in the silicone rubber matrix and the interfacial bonding strength with the matrix directly affect the conductivity and mechanical properties of the composite material. In addition, how to achieve the effective combination of graphene nanosheets and silicone rubber while maintaining the original excellent properties of graphene is a key technical problem that needs to be solved urgently. Summary of the invention

[0005] In order to solve the shortcomings of the prior art, a highly conductive composite material of silicone rubber reinforced with graphene nanosheets is provided, which specifically includes the following solutions:

[0006] A highly conductive composite material of silicone rubber reinforced with graphene nanosheets, wherein the preparation method of the composite material comprises the following steps:

[0007] S1: Hydroxyl-terminated polydimethylsiloxane was selected as the silicone rubber matrix and modified graphene nanosheets were used as the reinforcement material;

[0008] S2: Modification of graphene nanosheets;

[0009] S3: dispersing the modified graphene nanosheets;

[0010] S4: Mixing of composite materials: Mixing the dispersed graphene nanosheet solution with the silicone rubber matrix at a stirring speed of 300 rpm for 30 minutes; grinding using a three-roll mill;

[0011] S5: adding cross-linking agent and catalyst;

[0012] S6: Molding and vulcanization: The uniformly mixed composite material is injected into the mold and then vulcanized.

[0013] Furthermore, S2 also includes the following sub-steps:

[0014] S201: adding graphene nanosheets into an ethanol solution to prepare a dispersion with a concentration of 10 mg / mL;

[0015] S202: adding a 2 wt% (3-aminopropyl)triethoxysilane solution by volume to the dispersion; reacting for 2 hours under stirring, filtering, washing and drying to obtain modified graphene nanosheets.

[0016] Furthermore, S3 also includes the following steps: adding the modified graphene nanosheets at a ratio of 1 to 5 wt % to dimethyl silicone oil with a viscosity of 1000 cSt; dispersing by ultrasonic treatment, with an ultrasonic time of 30 minutes and an ultrasonic power of 200 to 400 W.

[0017] Furthermore, the number of grinding processes in S4 is 3 to 5 times, and the gap each time is set to 10 μm.

[0018] Furthermore, the cross-linking agent is methyltrimethoxysilane; and the catalyst is a platinum catalyst.

[0019] Furthermore, the molecular weight of the hydroxyl-terminated polydimethylsiloxane is 500,000 to 700,000 g / mol.

[0020] Furthermore, the graphene nanosheet has a thickness of 1 to 5 nm and a diameter of 1 to 10 μm.

[0021] Furthermore, the vulcanization parameters in S6 are vulcanization at 160° C. for 30 minutes and post-vulcanization at 180° C. for 4 hours.

[0022] Beneficial effects:

[0023] The present invention provides a highly conductive composite material of silicone rubber reinforced by graphene nanosheets, which specifically includes the following advantages:

[0024] (1) The use of hydroxyl-terminated polydimethylsiloxane as the base material can ensure the stability of the composite material in high temperature environments and enhance the material's aging resistance. At the same time, the material maintains the inherent flexibility of silicone rubber, so that the composite material has high conductivity while still maintaining excellent flexibility, and is suitable for devices of various complex shapes. The hydroxyl-terminated molecular structure is conducive to the reaction with the cross-linking agent to form a three-dimensional network structure, thereby improving the mechanical strength and wear resistance of the composite material.

[0025] (2) The surface of graphene nanosheets was modified by using (3-aminopropyl)triethoxysilane (APTES), which significantly improved the dispersion of graphene in the silicone rubber matrix and avoided the occurrence of agglomeration. The modified graphene nanosheets have more active groups on the surface and can form a stronger interface with the silicone rubber matrix, thereby improving the overall performance of the composite material. The modified graphene nanosheets are evenly dispersed in the silicone rubber matrix to form a stable conductive network, which greatly improves the conductivity of the material and is suitable for the manufacture of high-performance electronic components.

[0026] (3) Three-roll milling is used for processing. The use of a three-roll mill further breaks up graphene aggregates, refines the size of the dispersed phase, and improves the uniformity of the composite material. The gap between each grinding is set to 10 μm. After 3 to 5 grinding processes, the microstructure of the composite material is ensured to be more compact, thereby improving the conductivity and mechanical strength of the material. DETAILED DESCRIPTION

[0027] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0028] Example 1

[0029] Matrix material: Hydroxyl-terminated polydimethylsiloxane with a molecular weight of 600,000 g / mol Reinforcement material: Graphene nanosheets with a thickness of 2 nm and a diameter of 5 μm

[0030] S2: Modification of graphene nanosheets

[0031] S201: Adding graphene nanosheets into an ethanol solution to prepare a dispersion with a concentration of 10 mg / mL.

[0032] S202: Add 2 wt% (3-aminopropyl)triethoxysilane (APTES) solution to the dispersion and react for 2 hours under stirring. Then, filter the reaction product, wash it with ethanol three times and dry it to obtain modified graphene nanosheets.

[0033] S3: Dispersion of modified graphene nanosheets

[0034] The modified graphene nanosheets were added into dimethyl silicone oil with a viscosity of 1000 cSt at a ratio of 3 wt %.

[0035] Ultrasonic treatment was used for dispersion, the ultrasonic time was 30 minutes, and the ultrasonic power was set to 300W.

[0036] S4: Mixing of composite materials

[0037] The dispersed graphene nanosheet solution was mixed with the hydroxyl-terminated polydimethylsiloxane matrix at a stirring speed of 300 rpm for 30 minutes.

[0038] The grinding process was performed three times using a triple roll mill, and the gap between each grinding was set to 10 μm.

[0039] S5: Addition of crosslinking agent and catalyst

[0040] 1.5 wt% of methyltrimethoxysilane (MTMS) was added as a crosslinking agent.

[0041] A platinum catalyst of 50 ppm by mass was added.

[0042] S6: Molding and vulcanization

[0043] The mixed composite material was injected into the mold and vulcanized at 160°C for 30 minutes. After that, post-vulcanization treatment was carried out at 180°C for 4 hours.

[0044] Example 2

[0045] Matrix material: Hydroxyl-terminated polydimethylsiloxane with a molecular weight of 550,000 g / mol

[0046] Reinforcement material: Graphene nanosheets with a thickness of 3nm and a diameter of 8μm are selected.

[0047] S2: Modification of graphene nanosheets

[0048] S201: Adding graphene nanosheets into an ethanol solution to prepare a dispersion with a concentration of 10 mg / mL.

[0049] S202: Add 2 wt% (3-aminopropyl)triethoxysilane (APTES) solution to the dispersion and react for 2 hours under stirring. Filter the reaction product, wash it with ethanol three times and dry it to obtain modified graphene nanosheets.

[0050] S3: Dispersion of modified graphene nanosheets

[0051] The modified graphene nanosheets were added into dimethyl silicone oil with a viscosity of 1000 cSt at a ratio of 2 wt %.

[0052] Ultrasonic treatment was used for dispersion, the ultrasonic time was 30 minutes, and the ultrasonic power was set to 250W.

[0053] S4: Mixing of composite materials

[0054] The dispersed graphene nanosheet solution was mixed with the hydroxyl-terminated polydimethylsiloxane matrix at a stirring speed of 300 rpm for 30 minutes, and then ground four times using a three-roll mill, with the gap of each grinding being set to 10 μm.

[0055] S5: Addition of crosslinking agent and catalyst

[0056] 1 wt% of methyltrimethoxysilane (MTMS) was added as a crosslinking agent, and 50 ppm of platinum catalyst was added.

[0057] S6: Molding and vulcanization

[0058] The uniformly mixed composite material was injected into the mold and vulcanized at 160°C for 30 minutes.

[0059] Afterwards, post-vulcanization treatment was carried out at 180°C for 4 hours.

[0060] Example 3

[0061] Matrix material: Hydroxyl-terminated polydimethylsiloxane (HO-PDMS) with a molecular weight of 650,000 g / mol was selected.

[0062] Reinforcement material: Graphene nanosheets with a thickness of 4nm and a diameter of 7μm are selected.

[0063] S2: Modification of graphene nanosheets

[0064] S201: Adding graphene nanosheets into an ethanol solution to prepare a dispersion with a concentration of 10 mg / mL.

[0065] S202: Add 2 wt% (3-aminopropyl)triethoxysilane (APTES) solution to the dispersion and react for 2 hours under stirring. Filter the reaction product, wash it with ethanol three times and dry it to obtain modified graphene nanosheets.

[0066] S3: Dispersion of modified graphene nanosheets

[0067] The modified graphene nanosheets were added into dimethyl silicone oil with a viscosity of 1000 cSt at a ratio of 5 wt %.

[0068] Ultrasonic treatment was used for dispersion, the ultrasonic time was 30 minutes, and the ultrasonic power was set to 350W.

[0069] S4: Mixing of composite materials

[0070] The dispersed graphene nanosheet solution was mixed with the hydroxyl-terminated polydimethylsiloxane matrix at a stirring speed of 300 rpm for 30 minutes.

[0071] The grinding process was performed five times using a three-roll mill, and the gap between each grinding was set to 10 μm.

[0072] S5: Addition of crosslinking agent and catalyst

[0073] 2 wt% of methyltrimethoxysilane (MTMS) was added as a crosslinking agent.

[0074] A platinum catalyst of 50 ppm by mass was added.

[0075] S6: Molding and vulcanization

[0076] The uniformly mixed composite material was injected into the mold and vulcanized at 160°C for 30 minutes.

[0077] Afterwards, post-vulcanization treatment was carried out at 180°C for 4 hours.

[0078] Comparative Example:

[0079] The preparation process is similar to that of Examples 1 to 3, except that the graphene nanosheets are not modified.

[0080] The conductive properties of the silicone rubber high conductive composite materials obtained in Examples 1 to 3 and the comparative example were tested, and the test data are shown in the following table:

[0081]

[0082]

[0083] The comparative data in the above table show that the conductivity of the comparative sample without modifying the graphene nanosheets is significantly lower than that of Examples 1 to 3. In the examples, as the graphene content increases, the conductivity of the composite material increases, proving that the surface modification of the graphene nanosheets and the reasonable dispersion process significantly improve the conductive properties of the composite material.

[0084] As a further improvement, the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A highly conductive composite material of silicone rubber reinforced with graphene nanosheets, characterized in that: The method for preparing the composite material comprises the following steps: S1: Hydroxyl-terminated polydimethylsiloxane was selected as the silicone rubber matrix and modified graphene nanosheets were used as the reinforcement material; S2: Modification of graphene nanosheets; S3: dispersing the modified graphene nanosheets; S4: Mixing of composite materials: Mixing the dispersed graphene nanosheet solution with the silicone rubber matrix at a stirring speed of 300 rpm for 30 minutes; grinding using a three-roll mill; S5: adding cross-linking agent and catalyst; S6: Molding and vulcanization: The uniformly mixed composite material is injected into the mold and then vulcanized.

2. The highly conductive composite material of silicone rubber reinforced with graphene nanosheets according to claim 1, characterized in that: S2 also includes the following sub-steps: S201: adding graphene nanosheets into an ethanol solution to prepare a dispersion with a concentration of 10 mg / mL; S202: adding a 2 wt% (3-aminopropyl)triethoxysilane solution by volume to the dispersion; reacting for 2 hours under stirring, filtering, washing and drying to obtain modified graphene nanosheets.

3. The highly conductive composite material of silicone rubber reinforced with graphene nanosheets according to claim 1, characterized in that: S3 also includes the following steps: adding the modified graphene nanosheets at a ratio of 1 to 5 wt % into dimethyl silicone oil with a viscosity of 1000 cSt; dispersing by ultrasonic treatment, with an ultrasonic time of 30 minutes and an ultrasonic power of 200 to 400 W.

4. The highly conductive composite material of silicone rubber reinforced with graphene nanosheets according to claim 1, characterized in that: The number of grinding processes in S4 is 3 to 5 times, and the gap each time is set to 10 μm.

5. The highly conductive composite material of silicone rubber reinforced with graphene nanosheets according to claim 1, characterized in that: The crosslinking agent is methyltrimethoxysilane; the catalyst is a platinum catalyst.

6. The highly conductive composite material of silicone rubber reinforced with graphene nanosheets according to claim 1, characterized in that: The molecular weight of the hydroxyl-terminated polydimethylsiloxane is 500,000 to 700,000 g / mol.

7. The highly conductive composite material of silicone rubber reinforced with graphene nanosheets according to claim 1, characterized in that: The thickness of graphene nanosheets is 1 to 5 nm and the diameter is 1 to 10 μm.

8. The highly conductive composite material of silicone rubber reinforced with graphene nanosheets according to claim 1, characterized in that: The curing parameters in S6 are curing at 160°C for 30 minutes and post-curing at 180°C for 4 hours.

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