Hybrid heat-conducting EPDM (ethylene-propylene-diene monomer) composite foam material

Abstract

The invention discloses a hybrid heat-conducting EPDM (Ethylene-Propylene-Diene Monomer) composite foam material and belongs to the field of polymer composite foam materials. The EPDM composite foam material is prepared from EPDM particles, a heat-conducting hybrid composite filler, zinc oxide, stearic acid, a foaming agent AC, a cross-linking agent DCP and talcum powder as raw materials, and the heat-conducting hybrid composite filler is prepared by mixing acidified carbon black, carbon fiber loaded magnesium hydroxide and graphene oxide loaded silicon dioxide. The hybrid heat-conducting EPDM composite foam material is scientific and reasonable in formula and simple and practical in technological process, the compatibility of the hybrid heat-conducting composite filler and a matrix is good, the hybrid heat-conducting composite filler has good dispersity in the matrix, and a good heat-conducting effect and excellent mechanical properties can be achieved.

Description

Technical Field

[0001] The invention belongs to the field of polymer composite foaming materials, and particularly relates to a hybrid heat-conducting EPDM composite foaming material. Background Art

[0002] Ethylene propylene diene monomer (EPDM) is a copolymer of ethylene, propylene, and a small amount of a third monomer, obtained through curing and granulation. It is a type of ethylene propylene rubber. Among the many types of synthetic rubber materials, EPDM exhibits the high elasticity of traditional rubber at room temperature and the plasticity of ordinary plastics at high temperatures, combining the properties of both plastics and rubber. EPDM also boasts high production efficiency and can be produced using common thermoplastic processing techniques, such as melt blending and extrusion. EPDM also exhibits excellent chemical stability, electrical insulation, aging resistance, and water resistance, as well as good ductility, high strength, and high filling and plasticizing capacity. This has led to its widespread application in industries such as automotive engineering, construction, air conditioning, and refrigeration.

[0003] The thermal conductivity of general polymer materials, k, is less than 0.3W / (m·K), while the thermal conductivity of general foam materials, k, is less than 0.1W / (m·K). EPDM's poor thermal conductivity leads to significant heat accumulation during actual use, limiting its application. Therefore, it is necessary to functionalize EPDM foam materials to improve their thermal conductivity. Summary of the Invention

[0004] The object of the present invention is to provide a hybrid heat-conducting EPDM composite foam material, which has good heat-conducting effect and processing performance.

[0005] To achieve the above object, the present invention adopts the following technical solutions: A hybrid thermally conductive EPDM composite foam material comprises the following raw materials in parts by weight: 100 parts of EPDM particles, 2-10 parts of a thermally conductive hybrid composite filler, 2 parts of zinc oxide, 2 parts of stearic acid, 7 parts of a foaming agent AC (azodicarbonamide), 0.5 parts of a cross-linking agent DCP (diisopropyl peroxide), and 2-4 parts of talc.

[0006] Furthermore, the thermally conductive hybrid composite filler is made by mixing acidified carbon black (OCB), carbon fiber-supported magnesium hydroxide (CF@Mg(OH)2), and graphene oxide-supported silica (GO@SiO2) in a mass ratio of 1:1:3. The addition of this filler creates a fast, three-dimensional thermally conductive network within the EPDM rubber matrix, allowing accumulated heat to be more quickly dissipated through the thermally conductive network, thereby improving heat accumulation and enhancing the thermal conductivity of the EPDM rubber foam.

[0007] Furthermore, the preparation of the acidified carbon black OCB is to slowly mix 30 mL of concentrated nitric acid and 20 mL of concentrated sulfuric acid, add 4 g of carbon black, fully acidify and react for 4 hours, then centrifuge, and then vacuum dry the obtained black product at 60°C for 12 hours, take it out and grind it.

[0008] Furthermore, the preparation of the carbon fiber loaded magnesium hydroxide CF@Mg(OH)2 is to add 0.2g of silane coupling agent KH550 to 100mL of 95% volume concentration ethanol aqueous solution, ultrasonicate it at 25℃ for 30min to fully hydrolyze it, then transfer it to a 60℃ water bath for magnetic stirring, and slowly add 4g of carbon fiber, continue stirring and reacting for 4h, slowly add 2g of magnesium hydroxide, continue stirring and reacting for 4h, stir at room temperature for 2h and let it stand overnight, finally centrifuge the reaction mixture, and place the obtained gray precipitate in a 60℃ vacuum drying oven to dry for 12h.

[0009] Furthermore, the preparation of the graphene oxide-supported silicon dioxide GO@SiO2 comprises the following steps: a) Preparation of graphene oxide using the Hummers method: 1 g of flake graphite was weighed and added to 60 mL of concentrated sulfuric acid. The mixture was stirred at room temperature for 30 min, then heated to 40°C, and 5 g of potassium permanganate was slowly added at a rate of 0.5 g every 10 min. The mixture was reacted for 6 h until the solution became viscous. 100 mL of deionized water was slowly added to dilute the reaction solution. The temperature was raised to 80°C, and 5 vol% hydrogen peroxide solution was then added dropwise until the system turned yellow and no bubbles emerged. 25 mL of 30 vol% hydrochloric acid solution was then added to the system. Finally, deionized water was added to the mixture until the volume reached 1 L. The mixture was allowed to stand for 12 h, washed, and centrifuged until the eluate was neutral. The eluate was freeze-dried for 48 h to obtain graphene oxide (GO). b) 0.2 g of silane coupling agent KH550 was added to 100 mL of 95% ethanol aqueous solution and ultrasonically hydrolyzed at 25 °C for 30 min. The mixture was then transferred to a 60 °C water bath for magnetic stirring. Subsequently, 2 g of the prepared graphene oxide was added and ultrasonically dispersed for 30 min. The mixture was stirred and reacted for 4 h. 0.5 g of nano-silica was then slowly added and stirred for 4 h. The mixture was stirred at room temperature for 2 h and allowed to stand overnight. The mixture was then centrifuged and freeze-dried for 48 h to obtain graphene oxide-loaded silica GO@SiO2.

[0010] Furthermore, the preparation of the hybrid thermally conductive EPDM composite foam material comprises the following steps: 1) EPDM particles, thermal conductive hybrid composite filler, zinc oxide, stearic acid, foaming agent AC, crosslinking agent DCP and talc are uniformly mixed in a two-roll mill preheated to 50-60°C for 10-20 minutes, and then thinly passed 4-6 times to obtain a rubber sheet with a thickness of 2-4 mm; 2) After the obtained rubber sheet is left to air at room temperature for 4-6 hours, it is compression-foamed at 175° C. and 10 MPa for 450 seconds, and after cooling, the hybrid thermally conductive EPDM composite foam material is obtained.

[0011] The beneficial effects of the present invention are: (1) The present invention prepares a thermally conductive hybrid composite filler by compounding acidified carbon black (OCB), carbon fiber-loaded magnesium hydroxide (CF@Mg(OH)2) and graphene oxide-loaded silicon dioxide (GO@SiO2), and applies it to EPDM foaming materials. The formula is scientific and reasonable, and the process flow is simple and practical.

[0012] (2) The hybrid thermally conductive composite filler prepared by the present invention has good compatibility with the matrix and can be well dispersed in the matrix, thereby being able to exert good thermal conductivity and excellent mechanical properties, significantly improving the thermal conductivity and processing performance of the EPDM foam material. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of the simulation of the hybrid thermally conductive composite filler prepared in the present invention in the EPDM matrix.

[0014] Figure 2 The SEM image (a) and FTIR image (b) of carbon fiber loaded magnesium hydroxide CF@Mg(OH)2 prepared in the example.

[0015] Figure 3 The SEM image (a) and FTIR image (b) of graphene oxide-supported silicon dioxide GO@SiO2 prepared in the example.

[0016] Figure 4 SEM images of the EPDM foam materials prepared in Example 2 (a) and Comparative Example 1 (b). DETAILED DESCRIPTION

[0017] A hybrid thermally conductive EPDM composite foam material, the preparation steps of which are as follows: 1) Oxidized carbon black (OCB), carbon fiber-supported magnesium hydroxide (CF@Mg(OH)2), and graphene oxide-supported silicon dioxide (GO@SiO2) were mixed in a mass ratio of 1:1:3 to obtain a thermally conductive hybrid composite filler; 2) Weigh, by weight, 100 parts of EPDM particles, 2-10 parts of thermally conductive hybrid composite filler, 2 parts of zinc oxide, 2 parts of stearic acid, 7 parts of foaming agent AC (azodicarbonamide), 0.5 parts of cross-linking agent DCP (dicumyl peroxide), and 2-4 parts of talc; 3) Use a two-roll mill preheated to 50-60°C to mix EPDM particles, thermal conductive hybrid composite filler, zinc oxide, stearic acid, foaming agent AC, crosslinking agent DCP and talc for 10-20 minutes. After the rubber material is completely mixed, pass it through the mill 4-6 times to obtain a rubber sheet with a thickness of 2-4 mm. 4) After the obtained rubber sheet is left to air at room temperature for 4-6 hours, it is placed in the mold cavity of a preheated flat-plate molding machine and molded and foamed for 450 seconds at 175°C and 10 MPa. After cooling, a hybrid thermally conductive EPDM composite foam material is obtained.

[0018] like Figure 1 In the hybrid thermally conductive composite filler prepared by the present invention, the use of graphene oxide loaded with silica can expand the contact area with the EPDM matrix, and interconnect with the carbon fiber loaded with hydroxide to form a thermal conductive network, while the filling of acidified carbon black can further enhance the thermal conductivity.

[0019] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0020] All materials used in the examples can be purchased from the market; EPDM particles were purchased from DuPont, USA; the carbon fiber used was carbon fiber powder with a monofilament diameter of 5 μm and a mesh size of 300 mesh; and the silicon dioxide used was nanosilicon dioxide with a particle size of 20-50 nm.

[0021] The preparation steps of the thermally conductive hybrid composite filler used in the embodiment are as follows: 1) Preparation of OCB: Slowly mix 30 mL of concentrated nitric acid (68%) and 20 mL of concentrated sulfuric acid (98%), add 4 g of carbon black, and fully acidify for 4 hours before centrifugation. The resulting black product is then vacuum-dried at 60°C for 12 hours, removed, and ground to obtain OCB. 2) Preparation of carbon fiber supported magnesium hydroxide CF@Mg(OH)2: 0.2 g of silane coupling agent KH550 was added to 100 mL of 95 vol% ethanol aqueous solution, and ultrasonicated at 25 ° C for 30 min to fully hydrolyze it. Then, it was transferred to a 60 ° C water bath for magnetic stirring, and 4 g of carbon fiber was slowly added. After continuing to stir and react for 4 hours, 2 g of magnesium hydroxide was slowly added. After continuing to stir and react for 4 hours, it was stirred at room temperature for 2 hours and then allowed to stand overnight. Finally, the reaction mixture was centrifuged, and the resulting gray precipitate was placed in a 60 ° C vacuum drying oven and dried for 12 hours to obtain carbon fiber supported magnesium hydroxide CF@Mg(OH)2; 3) Preparation of graphene oxide loaded silicon dioxide GO@SiO2: a) Preparation of graphene oxide using the Hummers method: 1 g of flake graphite was added to 60 mL of concentrated sulfuric acid (98%), stirred at room temperature for 30 min, then heated to 40°C, and 5 g of potassium permanganate was slowly added at a rate of 0.5 g every 10 min. After reacting for 6 h until the solution became viscous, 100 mL of deionized water was slowly added to dilute the reaction solution. At the same time, the temperature was raised to 80°C, and 5 vol% hydrogen peroxide solution was then added dropwise until the system turned yellow and no bubbles emerged. 25 mL of 30 vol% hydrochloric acid solution was then added to the system. Finally, deionized water was added to the mixture until the volume reached 1 L. After standing for 12 h, the mixture was washed and centrifuged until the eluate was neutral, and then freeze-dried in a freeze dryer for 48 h to obtain graphene oxide (GO). b) 0.2 g of silane coupling agent KH550 was added to 100 mL of 95 vol% ethanol aqueous solution and ultrasonically hydrolyzed at 25 °C for 30 min. The mixture was then transferred to a 60 °C water bath for magnetic stirring. 2 g of the prepared graphene oxide was then added and ultrasonically dispersed for 30 min. The mixture was stirred and reacted for 4 h. 0.5 g of nano-silica was then slowly added and stirred for 4 h. The mixture was stirred at room temperature for 2 h and allowed to stand overnight. The mixture was then centrifuged and dried in a freeze dryer for 48 h to obtain graphene oxide-loaded silica (GO@SiO2). 4) The prepared acidified carbon black OCB, carbon fiber-loaded magnesium hydroxide CF@Mg(OH)2 and graphene oxide-loaded silicon dioxide GO@SiO2 were mixed in a mass ratio of 1:1:3 to obtain a thermally conductive hybrid composite filler.

[0022] Figure 2 The SEM and FTIR images of the prepared carbon fiber loaded magnesium hydroxide CF@Mg(OH)2 are shown. As can be seen from the figure, the prepared carbon fiber loaded magnesium hydroxide CF@Mg(OH)2 presents a good separation state. On the surface of the carbon fiber, it can be clearly seen that the magnesium hydroxide particles loaded thereon are in a clustered and fluffy state, with a high loading amount and uniform distribution (a). At the same time, its-1 The characteristic peak corresponding to the silane coupling agent is 1601cm -1 Corresponding to the characteristic peak of carbon fiber, 3412-3508cm -1 Corresponding to the characteristic peak of magnesium hydroxide or adsorbed water, 3698cm -1 The characteristic peak corresponding to magnesium hydroxide proves that magnesium hydroxide has successfully adhered to the surface of the acidified carbon fiber CF (b).

[0023] Figure 3 The SEM and FTIR images of the prepared graphene oxide supported silica GO@SiO2 are shown in Figure 1. As can be seen from the figure, the prepared graphene oxide supported silica GO@SiO2 is in the form of wrinkled nanosheets, and silica particles (a) are present on the surface of graphene oxide. At the same time, its -1 and 790cm -1 Corresponding to the characteristic peak of surface silica, 1116 cm -1 The characteristic peak corresponding to the fusion of silica and silane coupling agent, 1633 cm -1 and 1726cm -1 Corresponding to the characteristic peak of graphene oxide, 3200-3400cm -1 The characteristic peaks of hydroxyl groups corresponding to graphene oxide or adsorbed water prove that silicon dioxide is successfully attached to the surface of graphene oxide GO (b).

[0024] Example 1 The preparation steps of a hybrid thermal conductive EPDM composite foam material are as follows: 1) By weight, 100 parts of EPDM particles, 2 parts of thermally conductive hybrid composite filler, 2 parts of zinc oxide, 2 parts of stearic acid, 7 parts of foaming agent AC, 0.5 parts of crosslinking agent DCP, and 4 parts of talc were added to a two-roll mill and mixed at 50°C for 20 minutes to uniformly mix all the ingredients. The mixture was then pressed into 4 mm thin sheets using the two-roll mill and allowed to dry at room temperature for 3 hours. 2) placing the sheet prepared in step 1) in a film cavity of a preheated flat-plate molding machine, performing compression molding and foaming for 450 seconds at 10 MPa and 175° C., and then taking it out to obtain a hybrid thermally conductive EPDM composite foam material.

[0025] Example 2 The preparation steps of a hybrid thermal conductive EPDM composite foam material are as follows: 1) By weight, 100 parts of EPDM particles, 6 parts of thermally conductive hybrid composite filler, 2 parts of zinc oxide, 2 parts of stearic acid, 7 parts of foaming agent AC, 0.5 parts of crosslinking agent DCP, and 4 parts of talc were added to a two-roll mill and mixed at 50°C for 20 minutes to uniformly mix all the ingredients. The mixture was then pressed into 4 mm thin sheets using the two-roll mill and allowed to dry at room temperature for 3 hours. 2) placing the sheet prepared in step 1) in a film cavity of a preheated flat-plate molding machine, performing compression molding and foaming for 450 seconds at 10 MPa and 175° C., and then taking it out to obtain a hybrid thermally conductive EPDM composite foam material.

[0026] Example 3 The preparation steps of a hybrid thermal conductive EPDM composite foam material are as follows: 1) By weight, 100 parts of EPDM particles, 10 parts of thermally conductive hybrid composite filler, 2 parts of zinc oxide, 2 parts of stearic acid, 7 parts of foaming agent AC, 0.5 parts of crosslinking agent DCP, and 4 parts of talc were added to a two-roll mill and mixed at 50°C for 20 minutes to uniformly mix all the ingredients. The mixture was then pressed into 4 mm thin sheets using the two-roll mill and allowed to dry at room temperature for 3 hours. 2) placing the sheet prepared in step 1) in a film cavity of a preheated flat-plate molding machine, performing compression molding and foaming for 450 seconds at 10 MPa and 175° C., and then taking it out to obtain a hybrid thermally conductive EPDM composite foam material.

[0027] Comparative Example 1 The preparation steps of an EPDM composite foam material are as follows: 1) Add 100 parts by weight of EPDM particles, 2 parts of zinc oxide, 2 parts of stearic acid, 7 parts of foaming agent AC, 0.5 parts of crosslinking agent DCP, and 4 parts of talc to a two-roll mill and mix at 50°C for 20 minutes to evenly mix all the ingredients. Then, press the mixture into 4 mm thin sheets on the two-roll mill and air-dry them at room temperature for 3 hours. 2) The sheet prepared in step 1) is placed in a film cavity of a preheated flat-plate molding machine, and is molded and foamed for 450 seconds under conditions of 10 MPa and 175° C., and then taken out to obtain an EPDM composite foam material.

[0028] Comparative Example 2 The preparation steps of an EPDM composite foam material are as follows: 1) By weight, 100 parts of EPDM particles, 6 parts of acidified carbon black, 2 parts of zinc oxide, 2 parts of stearic acid, 7 parts of foaming agent AC, 0.5 parts of crosslinking agent DCP, and 4 parts of talc were added to a two-roll mill and mixed at 50°C for 20 minutes to uniformly mix all the ingredients. The mixture was then pressed into 4 mm thin sheets using a two-roll mill and allowed to dry at room temperature for 3 hours. 2) The sheet prepared in step 1) is placed in a film cavity of a preheated flat-plate molding machine, and is molded and foamed for 450 seconds under conditions of 10 MPa and 175° C., and then taken out to obtain an EPDM composite foam material.

[0029] Comparative Example 3 The preparation steps of an EPDM composite foam material are as follows: 1) By weight, 100 parts of EPDM particles, 6 parts of carbon fiber-supported magnesium hydroxide, 2 parts of zinc oxide, 2 parts of stearic acid, 7 parts of foaming agent AC, 0.5 parts of crosslinking agent DCP, and 4 parts of talc were added to a two-roll mill and mixed at 50°C for 20 minutes to uniformly mix all the ingredients. The mixture was then pressed into 4 mm thin sheets using a two-roll mill and allowed to dry at room temperature for 3 hours. 2) The sheet prepared in step 1) is placed in a film cavity of a preheated flat-plate molding machine, and is molded and foamed for 450 seconds under conditions of 10 MPa and 175° C., and then taken out to obtain an EPDM composite foam material.

[0030] Comparative Example 4 The preparation steps of an EPDM composite foam material are as follows: 1) By weight, 100 parts of EPDM particles, 6 parts of graphene oxide-loaded silica, 2 parts of zinc oxide, 2 parts of stearic acid, 7 parts of foaming agent AC, 0.5 parts of crosslinking agent DCP, and 4 parts of talc were added to a two-roll mill and mixed at 50°C for 20 minutes to uniformly mix all the ingredients. The mixture was then pressed into 4 mm thin sheets using a two-roll mill and allowed to dry at room temperature for 3 hours. 2) The sheet prepared in step 1) is placed in a film cavity of a preheated flat-plate molding machine, and is molded and foamed for 450 seconds under conditions of 10 MPa and 175° C., and then taken out to obtain an EPDM composite foam material.

[0031] Comparative Example 5 The preparation steps of an EPDM composite foam material are as follows: 1) A composite thermal conductive filler is obtained by mixing acidified carbon black, carbon fiber, magnesium hydroxide, and graphene oxide-loaded silica in a mass ratio of 3:2:1:9; 2) EPDM particles 100 parts, composite heat-conductive filler 6 parts, zinc oxide 2 parts, stearic acid 2 parts, foaming agent AC 7 parts, crosslinking agent DCP 0.5 parts, talc 4 parts were added into a double roller open mill, mixed at 50°C for 20 min, so that all raw materials were uniformly mixed, then pressed into 4mm sheet by using the double roller open mill, and the obtained sheet was dried at room temperature for 3h; 3) The sheet prepared in step 2) was placed in the film cavity of a preheated flat plate mold press, and after being molded and foamed at 10MPa, 175°C for 450s, it was taken out, to obtain the EPDM composite foaming material.

[0032] Comparative Example 6 The preparation steps of the EPDM composite foaming material were as follows: 1) Acidified carbon black, carbon fiber loaded magnesium hydroxide, graphene oxide and silicon dioxide were mixed in a mass ratio of 5:5:12:3 to obtain a composite heat-conductive filler; 2) EPDM particles 100 parts, composite heat-conductive filler 6 parts, zinc oxide 2 parts, stearic acid 2 parts, foaming agent AC 7 parts, crosslinking agent DCP 0.5 parts, talc 4 parts were added into a double roller open mill, mixed at 50°C for 20 min, so that all raw materials were uniformly mixed, then pressed into 4mm sheet by using the double roller open mill, and the obtained sheet was dried at room temperature for 3h; 3) The sheet prepared in step 2) was placed in the film cavity of a preheated flat plate mold press, and after being molded and foamed at 10MPa, 175°C for 450s, it was taken out, to obtain the EPDM composite foaming material.

[0033] Figure 4 SEM image of the hybrid heat-conductive EPDM composite foaming material prepared in Example 2. From the figure, it can be seen that the hybrid heat-conductive EPDM composite foaming material prepared by the present application has a relatively uniform cell distribution, and the prepared carbon fiber loaded magnesium hydroxide CF@Mg(OH)2 and other hybrid heat-conductive fillers have good dispersibility therein.

[0034] The samples obtained in the examples and comparative examples were tested for performance, and the results are shown in Table 1.

[0035] Table 1 Performance test results of samples

[0036] The data in Table 1 show that the thermal conductivity of the composite foam material containing the hybrid thermally conductive composite filler increases with increasing filler content: when the filler content is 6 parts, the thermal conductivity of the sample increases to 0.3095 W / (m·K); when the filler content reaches 10 parts, the thermal conductivity of the sample increases to 0.0.4345 W / (m·K). Furthermore, as the amount of hybrid thermally conductive composite filler increases, the tensile strength and elongation at break of the sample also increase. This demonstrates that the use of hybrid thermally conductive composite fillers can also effectively improve the mechanical properties of the sample. This is because the carbon fiber-loaded magnesium hydroxide and graphene-loaded silica can build a three-dimensional hybrid conductive network within the composite foam material, allowing it to tightly bond with the matrix material, thereby improving the mechanical properties of the EPDM foam material. Among them, Example 2 exhibits the best overall performance.

[0037] At the same time, compared with Comparative Example 1, which did not add filler, Comparative Examples 2-4, which added only a single filler component, and Comparative Examples 5 and 6, which simply mixed the filler components, the thermal conductivity of the hybrid thermally conductive EPDM composite foam material prepared in Example was significantly improved. This is due to the special effect of carbon fiber-loaded magnesium hydroxide penetrating the pores of the EPDM foam material, which reduces the gap spacing and the pore diameter, thereby shortening the thermal conductivity gap and improving thermal conductivity. In addition, the carbon fiber-loaded magnesium hydroxide and graphene oxide-loaded silica can form a three-dimensional thermal conductive network, improving thermal conductivity efficiency. The addition of acidified carbon black can effectively fill the gaps in the three-dimensional thermal conductive network, further improving the thermal conductivity of the EPDM foam material. This proves that the specific composition of the thermally conductive hybrid composite filler of the present invention can play a synergistic role in thermal conductivity.

[0038] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A hybrid thermally conductive EPDM composite foam material, characterized by: The raw materials used include, by weight: 100 parts of EPDM particles, 2-10 parts of thermal conductive hybrid composite filler, 2 parts of zinc oxide, 2 parts of stearic acid, 7 parts of foaming agent AC, 0.5 parts of cross-linking agent DCP, and 2-4 parts of talc.

2. The hybrid thermally conductive EPDM composite foam material according to claim 1, characterized in that: The thermal conductive hybrid composite filler is prepared by mixing acidified carbon black (OCB), carbon fiber-loaded magnesium hydroxide (CF@Mg(OH)2) and graphene oxide-loaded silicon dioxide (GO@SiO2) in a mass ratio of 1:1:

3.

3. The hybrid thermally conductive EPDM composite foam material according to claim 2, characterized in that: The preparation of the acidified carbon black OCB is as follows: 30 mL of concentrated nitric acid and 20 mL of concentrated sulfuric acid are slowly mixed, 4 g of carbon black is added, and the mixture is fully acidified for 4 hours and then centrifuged. The obtained black product is then vacuum dried at 60° C. for 12 hours, taken out, and then ground to obtain the product.

4. The hybrid thermally conductive EPDM composite foam material according to claim 2, characterized in that: The preparation of the carbon fiber-loaded magnesium hydroxide CF@Mg(OH)2 is as follows: 0.2 g of silane coupling agent KH550 is added to 100 mL of 95% ethanol aqueous solution, ultrasonicated at 25°C for 30 minutes to fully hydrolyze it, then transferred to a 60°C water bath for magnetic stirring, and 4 g of carbon fiber is slowly added. After continuing to stir and react for 4 hours, 2 g of magnesium hydroxide is slowly added. After continuing to stir and react for 4 hours, the mixture is stirred at room temperature for 2 hours and then allowed to stand overnight. Finally, the reaction mixture is centrifuged, and the resulting gray precipitate is placed at 60°C and dried for 12 hours.

5. The hybrid thermally conductive EPDM composite foam material according to claim 2, characterized in that: The preparation of the graphene oxide-supported silicon dioxide GO@SiO2 comprises the following steps: a) Preparation of graphene oxide using the Hummers method: 1 g of flake graphite was weighed and added to 60 mL of concentrated sulfuric acid. The mixture was stirred at room temperature for 30 min, then heated to 40°C, and 5 g of potassium permanganate was slowly added at a rate of 0.5 g every 10 min. The mixture was reacted for 6 h until the solution became viscous. 100 mL of deionized water was slowly added to dilute the reaction solution. The temperature was raised to 80°C, and 5 vol% hydrogen peroxide solution was then added dropwise until the system turned yellow and no bubbles emerged. 25 mL of 30 vol% hydrochloric acid solution was then added to the system. Finally, deionized water was added to the mixture until the volume reached 1 L. After standing for 12 h, the mixture was washed and centrifuged until the eluate was neutral, and freeze-dried to obtain graphene oxide (GO). b) 0.2 g of silane coupling agent KH550 was added to 100 mL of 95% ethanol aqueous solution and ultrasonically hydrolyzed at 25 °C for 30 min. The mixture was then transferred to a 60 °C water bath for magnetic stirring. Subsequently, 2 g of the prepared graphene oxide was added and ultrasonically dispersed for 30 min. The mixture was stirred and reacted for 4 h. Then, 0.5 g of nano-silica was slowly added and the mixture was stirred and reacted for 4 h. The mixture was stirred at room temperature for 2 h and allowed to stand overnight. The mixture was then centrifuged and freeze-dried to obtain graphene oxide-loaded silica GO@SiO2.

6. The hybrid thermally conductive EPDM composite foam material according to claim 1, characterized in that: Its preparation comprises the following steps: 1) EPDM particles, thermal conductive hybrid composite filler, zinc oxide, stearic acid, foaming agent AC, crosslinking agent DCP and talc are uniformly mixed in a two-roll mill preheated to 50-60°C for 10-20 minutes, and then thinly passed 4-6 times to obtain a rubber sheet with a thickness of 2-4 mm; 2) After the obtained rubber sheet is left to air at room temperature for 4-6 hours, it is compression-foamed at 175° C. and 10 MPa for 450 seconds, and after cooling, the hybrid thermally conductive EPDM composite foam material is obtained.

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