Graphite-carbon nanotube heat-conducting electromagnetic shielding composite material and preparation method thereof

Abstract

The invention provides a graphite-carbon nanotube heat-conducting electromagnetic shielding composite material and a preparation method thereof, belongs to the technical field of composite materials, and solves the problem that an existing nylon material cannot meet the requirements of efficient heat dissipation performance and electromagnetic interference shielding performance at the same time. The graphite-carbon nanotube heat-conducting electromagnetic shielding composite material is prepared from the following components in parts by weight: 39 to 80 parts of nylon, 20 to 40 parts of crystalline flake graphite, 1 to 4 parts of aminated multi-arm carbon nanotubes, 0.1 to 0.3 part of a lubricating agent and 0.3 to 0.5 part of an antioxidant. The heat conduction and heat dissipation performance, the electromagnetic shielding performance and the mechanical performance of the nylon composite material are improved through a synergistic enhancement system of the crystalline flake graphite and the aminated multi-arm carbon nanotubes.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, specifically to a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material and its preparation method. Background Technology

[0002] Nylon (such as nylon 6), as an important material in the field of engineering plastics, is widely used in components such as engine covers, motor housings, and electronic control unit housings due to its excellent mechanical strength, chemical corrosion resistance, ease of processing, and low cost. However, nylon's inherent low thermal conductivity (for example, the thermal conductivity of nylon 6 is approximately 0.25 W / (m·K)) and poor electromagnetic shielding effectiveness severely limit its application in high-end scenarios. For example, in key components such as power battery module brackets, sensor brackets, electronic control system housings, and automotive 5G communication modules, materials must simultaneously meet requirements for efficient heat dissipation and electromagnetic interference shielding, characteristics that pure nylon cannot simultaneously possess. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material and its preparation method. The thermal conductivity, electromagnetic shielding performance and mechanical properties of nylon composite material are improved by the synergistic reinforcement system of flake graphite and aminated multi-arm carbon nanotubes.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material, comprising the following components: 39-80 parts by weight of nylon, 20-40 parts by weight of flake graphite, 1-4 parts by weight of ammoniated multi-arm carbon nanotubes, 0.1-0.3 parts by weight of lubricant and 0.3-0.5 parts by weight of antioxidant.

[0005] Optionally, the graphite-carbon nanotube thermal and electromagnetic shielding composite material includes the following components: 65.4 parts by weight of nylon, 30 parts by weight of flake graphite, 4 parts by weight of ammoniated multi-arm carbon nanotubes, 0.2 parts by weight of lubricant and 0.4 parts by weight of antioxidant.

[0006] Optionally, the particle size distribution of the flake graphite is: D90 greater than 10 micrometers.

[0007] Optionally, the nylon is PA6.

[0008] Optionally, the graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material further includes a toughening agent, wherein the toughening agent is a maleic anhydride-grafted polyolefin elastomer.

[0009] Optionally, the toughening agent is present in a content of 3-5 parts by weight.

[0010] Optionally, the graphite-carbon nanotube thermally and electromagnetically shielding composite material includes: 60.4 parts by weight of nylon, 30 parts by weight of flake graphite, 4 parts by weight of ammoniated multi-arm carbon nanotubes, 5 parts by weight of toughening agent, 0.2 parts by weight of lubricant and 0.4 parts by weight of antioxidant.

[0011] Secondly, the present invention also provides a method for preparing a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material, used to prepare the above-mentioned graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material, the preparation method comprising: Step (A-1): Mix nylon, flake graphite, aminated multi-arm carbon nanotubes, lubricant, and antioxidant evenly to obtain a mixture; Step (A-2): The mixture is extruded and granulated in a twin-screw extruder to obtain composite material particles; Step (A-3): The composite material particles are dried in a blower oven and then injection molded in an injection molding machine.

[0012] Optionally, a toughening agent may also be added in step (A-1).

[0013] Optionally, the preparation method of the aminated multi-arm carbon nanotubes includes the following steps: Step (B-1): Carboxylated multi-arm carbon nanotubes, sulfoxide and solvent are mixed and subjected to acyl chloride reaction to obtain acyl chloride multi-arm carbon nanotubes; Step (B-2): Acyl chloride multi-arm carbon nanotubes are mixed with an organic amine solution to carry out an amination reaction, thereby obtaining amination-treated multi-arm carbon nanotubes.

[0014] The above-described solution of the present invention has at least the following beneficial effects: The graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material of this invention comprises nylon, flake graphite, aminated multi-arm carbon nanotubes, a lubricant, and an antioxidant. It utilizes the high internal thermal conductivity of the flake graphite's ultra-high surface area to dominate heat transfer, while the aminated multi-arm carbon nanotubes act as "nano-thermal bridges" connecting the interlayer gaps of the flake graphite, forming a three-dimensional thermally conductive network. This significantly reduces interfacial thermal resistance and improves the composite material's heat dissipation performance. The aminated multi-arm carbon nanotubes construct a conductive main network to dissipate electromagnetic energy, and the flake graphite enhances wave attenuation through multiple reflections / scatterings, achieving a dual-effect electromagnetic shielding of "reflection-absorption-reflection." Simultaneously, the excellent dispersion and interfacial bonding of the aminated multi-arm carbon nanotubes within the nylon matrix also exhibit a nano-reinforcement effect, further enhancing the composite material's mechanical properties. Therefore, this composite material simultaneously possesses excellent thermal conductivity and heat dissipation performance, electromagnetic shielding performance, and mechanical properties. Attached Figure Description

[0015] Figure 1This is a flowchart illustrating the preparation process of the aminated multi-arm carbon nanotubes of the present invention. Detailed Implementation

[0016] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0017] On one hand, the present invention provides a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material, comprising the following components: 39-80 parts by weight of nylon, 20-40 parts by weight of flake graphite, 1-4 parts by weight of aminated multi-arm carbon nanotubes, 0.1-0.3 parts by weight of lubricant and 0.3-0.5 parts by weight of antioxidant.

[0018] For example, the nylon is in the following weight proportions: 39, 40, 50, 60, 70, 80, etc.; the flake graphite is in the following weight proportions: 20, 25, 30, 35, 40, etc.; the aminated multi-arm carbon nanotubes are in the following weight proportions: 1, 2, 3, 4, etc.; the lubricant is in the following weight proportions: 0.1, 0.2, 0.3, etc.; and the antioxidant is in the following weight proportions: 0.3, 0.4, 0.5, etc.

[0019] In a preferred embodiment, the graphite-carbon nanotube thermal and electromagnetic shielding composite material comprises the following components: 65.4 parts by weight of nylon, 30 parts by weight of flake graphite, 4 parts by weight of amination-modified multi-arm carbon nanotubes, 0.2 parts by weight of lubricant, and 0.4 parts by weight of antioxidant.

[0020] For example, the particle size of the flake graphite is less than 300 mesh, such as 200 mesh, 100 mesh, 80 mesh, 50 mesh, preferably 100 mesh flake graphite. The larger the flakes of graphite, the more advantageous it is for constructing a continuous thermally conductive network. With larger flakes, there are fewer interfaces for the same mass fraction, resulting in lower interfacial thermal resistance and higher thermal conductivity of the composite material.

[0021] For example, the nylon is one of PA6, PA66, PPA, and PA612. PA6 is preferred.

[0022] To improve the processing stability of the material, that is, when the composite material requires toughness, preferably, the graphite-carbon nanotube thermally conductive electromagnetic shielding composite material also includes a toughening agent. For example, the toughening agent is a maleic anhydride-grafted polyolefin elastomer. Especially for the PA6 system, when the material is subjected to impact, the maleic anhydride-grafted polyolefin elastomer induces multiple crazing and shear yielding of the matrix, thereby effectively absorbing and dissipating a large amount of energy, reducing the embrittlement effect of flake graphite on PA6, and enabling the PA6 composite material to have thermal conductivity, electromagnetic shielding properties, processing stability, and mechanical properties.

[0023] For example, the toughening agent content is 3-5 parts by weight, such as 3 parts by weight, 4 parts by weight, or 5 parts by weight.

[0024] In a preferred embodiment, the graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material comprises: 60.4 parts by weight of nylon, 30 parts by weight of flake graphite, 4 parts by weight of amination-modified multi-arm carbon nanotubes, 5 parts by weight of toughening agent, 0.2 parts by weight of lubricant, and 0.4 parts by weight of antioxidant. Through the multiphase compounding of 30 parts by weight of flake graphite, 4 parts by weight of amination-modified multi-arm carbon nanotubes, and 5 parts by weight of toughening agent, a better balance can be achieved between rigidity, strength, and toughness, resulting in the composite material with optimal comprehensive mechanical properties.

[0025] For example, the lubricant is at least one of ethylene bis-stearamide, polyethylene wax, calcium stearate, zinc stearate, and silicone oil.

[0026] For example, the antioxidant includes hindered phenols and phosphites.

[0027] This invention introduces flake graphite (FG) and aminated multi-arm carbon nanotubes as hybrid fillers into nylon-based composite materials. This dual-system hybrid filler achieves a comprehensive improvement in the composite material's performance through three-dimensional network construction, interface optimization, and synergistic effects. The core mechanism lies in the following: two-dimensional FG sheets and one-dimensional aminated multi-arm carbon nanotubes form an interconnected three-dimensional network structure. The aminated multi-arm carbon nanotubes act as "nanobridges" connecting the dispersed FG sheets, significantly reducing interfacial thermal resistance and contact resistance. The -NH2 functional groups on their surface interact strongly with the amide bonds of the nylon matrix through strong hydrogen bonds, significantly enhancing interfacial bonding. The aminated multi-arm carbon nanotubes are used to construct a conductive main network to dissipate electromagnetic energy, while the flake graphite enhances wave attenuation through multiple reflections / scatterings, achieving a dual-effect electromagnetic shielding of "reflection-absorption-reflection." Simultaneously, combined with the toughening effect of the toughening agent maleic anhydride-grafted polyolefin elastomer, an optimized balance of rigidity, strength, and toughness is ultimately achieved, while also possessing heat dissipation and electromagnetic shielding properties.

[0028] Secondly, the present invention provides a method for preparing a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material, used to prepare the above-mentioned graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material, the preparation method comprising: Step (A-1): Mix nylon, flake graphite, aminated multi-arm carbon nanotubes, lubricant, and antioxidant evenly to obtain a mixture; Step (A-2): The mixture is extruded and granulated in a twin-screw extruder to obtain composite material particles; Step (A-3): The composite material particles are dried in a blower oven and then injection molded in an injection molding machine.

[0029] For example, a toughening agent is also added in step (A-1).

[0030] For example, in step (A-2), the length-to-diameter ratio of the twin-screw extruder is 40-50:1.

[0031] For example, in step (A-2), the twin-screw extruder rotates at a speed of 600-800 r / min.

[0032] For example, in step (A-2), the heating temperatures of the nine sections of the twin-screw extruder are as follows: 170-190℃, 240-260℃, 240-260℃, 230-250℃, 230-250℃, 220-240℃, 220-240℃, 220-240℃, 240-260℃.

[0033] For example, in step (A-3), the temperatures from the material feeding section to the nozzle of the injection molding machine are set sequentially as follows: 190-210℃, 230-250℃, 240-260℃, 250-270℃, and 250-270℃, and the injection pressure is 60-90MPa.

[0034] For example, such as Figure 1 As shown, the preparation method of the aminated multi-arm carbon nanotubes includes the following steps: Step (B-1): Carboxylated multi-arm carbon nanotubes, sulfoxide and solvent are mixed and subjected to acyl chloride reaction to obtain acyl chloride multi-arm carbon nanotubes; Step (B-2): Acyl chloride multi-arm carbon nanotubes are mixed with an organic amine solution to carry out an amination reaction, thereby obtaining amination-treated multi-arm carbon nanotubes.

[0035] For example, in step (B-1), the temperature of the acyl chloride reaction is 60-70°C and the time is 22-26 hours.

[0036] For example, in step (B-1), the ratio of carboxylated multi-arm carbon nanotubes, sulfoxide, and solvent is 100g:500mL:15mL.

[0037] For example, in step (B-1), the solvent is dimethylformamide (DMF).

[0038] For example, step (B-1) further includes: cooling the product of the acyl chloride reaction to room temperature, washing and filtering it with anhydrous tetrahydrofuran (THF) under N2 protection until the filtrate is clear; drying the product with N2 and then drying it in an oven at 80-90°C, and then grinding it to obtain acyl chloride multi-arm carbon nanotubes.

[0039] For example, in step (B-2), the organic amine solution is ethylenediamine.

[0040] For example, in step (B-2), the amination reaction is carried out at a temperature of 100-120°C for 70-74 hours.

[0041] For example, in step (B-2), the ratio of acyl chloride multi-arm carbon nanotubes to organic amine solution is 100g:500mL.

[0042] For example, step (B-2) further includes: cooling the product of the amination reaction to room temperature, washing and filtering it with anhydrous tetrahydrofuran (THF) under N2 protection until the filtrate is clear; then drying the product with N2 and placing it in an oven at 80-90°C to dry it, and then grinding it to obtain amination-modified multi-arm carbon nanotubes.

[0043] The following specific embodiments further illustrate the graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material and its preparation method of the present invention.

[0044] The sources of raw materials used in the following examples and comparative examples are shown in Table 1.

[0045] Table 1. Sources of raw materials in the examples and comparative examples.

[0046] Example 1 This embodiment provides a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material and its preparation method. The composition of the graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material is shown in Table 2. The preparation method of this graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material includes: Step (1): Weigh 100g of carboxylated multi-arm carbon nanotubes (MWCNTs), add them to a mixed solution of 500ml sulfoxide (SOCl2) and 15ml N,N-dimethylformamide (DMF), stir and react at 70℃ for 24h, cool the reaction product to room temperature, wash and filter with anhydrous tetrahydrofuran (THF) under N2 protection until the filtrate is clear, dry the product with N2 and place it in an oven at 80℃ to dry, and grind to obtain acyl chloride multi-arm carbon nanotubes; Step (2): Take 100g of the prepared acyl chloride multi-arm carbon nanotubes and add them to 500ml of ethylenediamine solution. Stir continuously for 72h at 110℃. After cooling the reaction product to room temperature, wash and filter with anhydrous THF under N2 protection until the filtrate is clear. Dry the product with N2 and place it in an oven at 80℃. After grinding, aminated multi-arm carbon nanotubes (MWCNTs-NH2) are obtained. Step (3): Nylon 6 (PA6), flake graphite (FG), aminated multi-arm carbon nanotubes (MWCNTs-NH2), lubricant (P130), antioxidants (RIANOX 168 and RIANOX 1010) are mixed evenly to obtain a mixture; Step (4): The mixture is extruded and granulated in a twin-screw extruder with a length-to-diameter ratio of 40:1. The speed of the twin-screw extruder is 600 r / min and the output is 25 kg / h. The heating temperatures of the nine sections of the twin-screw extruder are 180℃, 250℃, 250℃, 240℃, 240℃, 230℃, 230℃, 230℃, and 250℃, respectively, to obtain composite material particles. Step (5): After the composite material particles are dried in a blower oven, they are prepared into samples using an injection molding machine. The temperatures from the material feeding section to the nozzle of the injection molding machine are set sequentially as follows: 200℃, 240℃, 250℃, 260℃, and 260℃. The injection pressure is 80MPa.

[0047] Example 2 This embodiment provides a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material and its preparation method. The composition of the graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material is shown in Table 2. The preparation method of this graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material includes: Step (1): Weigh 100g of carboxylated multi-arm carbon nanotubes (MWCNTs), add them to a mixed solution of 500ml sulfoxide (SOCl2) and 15ml N,N-dimethylformamide (DMF), stir and react at 70℃ for 24h, cool the reaction product to room temperature, wash and filter with anhydrous tetrahydrofuran (THF) under N2 protection until the filtrate is clear, dry the product with N2 and place it in an oven at 80℃ to dry, and grind to obtain acyl chloride multi-arm carbon nanotubes; Step (2): Take 100g of the prepared acyl chloride multi-arm carbon nanotubes and add them to 500ml of ethylenediamine solution. Stir continuously for 72h at 110℃. After cooling the reaction product to room temperature, wash and filter with anhydrous THF under N2 protection until the filtrate is clear. Dry the product with N2 and place it in an oven at 80℃. After grinding, aminated multi-arm carbon nanotubes (MWCNTs-NH2) are obtained. Step (3): Nylon 6 (PA6), flake graphite (FG), aminated multi-arm carbon nanotubes (MWCNTs-NH2), maleic anhydride grafted POE (MD715), lubricant (P130), antioxidants (RIANOX 168 and RIANOX 1010) are mixed evenly to obtain a mixture; Step (4): The mixture is extruded and granulated in a twin-screw extruder with a length-to-diameter ratio of 40:1. The speed of the twin-screw extruder is 600 r / min and the output is 25 kg / h. The heating temperatures of the nine sections of the twin-screw extruder are 180℃, 250℃, 250℃, 240℃, 240℃, 230℃, 230℃, 230℃, and 250℃, respectively, to obtain composite material particles. Step (5): After the composite material particles are dried in a blower oven, they are prepared into samples using an injection molding machine. The temperatures from the material feeding section to the nozzle of the injection molding machine are set sequentially as follows: 200℃, 240℃, 250℃, 260℃, and 260℃. The injection pressure is 80MPa.

[0048] Comparative Example 1 This comparative example provides a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material and its preparation method similar to Example 1, except that PA6 is used in place of MWCNTs-NH2 in the same weight proportion, i.e., MWCNTs-NH2 is not added. As shown in Table 2.

[0049] Comparative Examples 2-4 This comparative example provides a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material and its preparation method similar to Example 1, except that the weight parts of MWCNTs-NH2 are 1, 2, and 6, respectively. As shown in Table 2.

[0050] Comparative Examples 5-6 This comparative example provides a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material and its preparation method similar to Example 2, except that the weight parts of maleic anhydride grafted with POE (MD715) are 3 and 7, respectively. As shown in Table 2.

[0051] Table 2. Parts by weight of each component in the composite materials of the Examples and Comparative Examples 1-6

[0052] Test case The mechanical properties, thermal conductivity, electrical conductivity, electromagnetic shielding properties, and heat dissipation properties of the composite materials prepared in the examples and comparative examples were tested.

[0053] The mechanical properties were tested using a Shimadzu AGS-X-10KN universal electronic tensile tester (ThermoFisher Scientific) to determine the tensile and bending mechanical properties of the composite material, according to ISO 527. The results are shown in Table 3. The thermal conductivity was tested using a Swedish Hot Disk TPS2500S tester. The sample size was 100×100×4 mm. The test method was the transient flat plate heat source method, and the test standard was ISO22007-2. The results are shown in Table 4. The conductivity test method is as follows: the surface resistance of the composite material is measured at room temperature using a B2985A high resistance meter. Each group of samples is tested 5 times and the average value is taken; the results are shown in Table 5. The electromagnetic shielding performance was tested using an Agilent PNA-5244A vector network analyzer in the 8.2-12.4 GHz (X-band) range. Electromagnetic shielding parameters, including the total shielding effectiveness (SE), were calculated using S-parameters. T Absorption and shielding effectiveness SE A , reflection shielding effectiveness SE R The sample size was 22.9×10.2×4mm; the results are shown in Table 6.

[0054] Table 3 Mechanical property test results

[0055] As can be seen from Table 3, the composite material containing both FG and MWCNTs-NH2 within the preferred range has higher tensile strength, flexural strength, flexural modulus and notched impact strength. When a toughening agent is added to the composite material containing FG and MWCNTs-NH2, the toughness of the composite material can be improved, but too much toughening agent (7 parts by weight) will affect the strength of the material.

[0056] Table 4 Thermal conductivity test results

[0057] As can be seen from Table 4, the composite material containing both FG and MWCNTs-NH2 has a high thermal conductivity, indicating that it has good heat dissipation.

[0058] Table 5. Conductivity test results

[0059] As can be seen from Table 5, the composite material containing both FG and MWCNTs-NH2 has high electrical conductivity, proving that well-dispersed MWCNTs-NH2 can bridge the FG layers and also improve the electrical conductivity.

[0060] Table 6 Electromagnetic shielding performance test results

[0061] As can be seen from Table 6, the composite material containing both FG and MWCNTs-NH2 has high electromagnetic shielding performance.

[0062] In summary, the graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material of the present invention possesses excellent thermal conductivity, electromagnetic shielding performance, and mechanical properties.

[0063] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material, characterized in that, Includes the following ingredients: 39-80 parts by weight of nylon, 20-40 parts by weight of flake graphite, 1-4 parts by weight of ammoniated multi-arm carbon nanotubes, 0.1-0.3 parts by weight of lubricant and 0.3-0.5 parts by weight of antioxidant.

2. The graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material according to claim 1, characterized in that, It includes the following components: 65.4 parts by weight of nylon, 30 parts by weight of flake graphite, 4 parts by weight of ammoniated multi-arm carbon nanotubes, 0.2 parts by weight of lubricant and 0.4 parts by weight of antioxidant.

3. The graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material according to claim 1, characterized in that, The particle size distribution of the flake graphite is: D90 greater than 10 micrometers.

4. The graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material according to claim 1, characterized in that, The nylon is PA6.

5. The graphite-carbon nanotube thermally and electromagnetically shielding composite material according to claim 4, characterized in that, The graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material also includes a toughening agent, which is a maleic anhydride-grafted polyolefin elastomer.

6. The graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material according to claim 5, characterized in that, The toughening agent content is 3-5 parts by weight.

7. The graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material according to claim 6, characterized in that, The graphite-carbon nanotube thermal and electromagnetic shielding composite material comprises: 60.4 parts by weight of nylon, 30 parts by weight of flake graphite, 4 parts by weight of amination-modified multi-arm carbon nanotubes, 5 parts by weight of toughening agent, 0.2 parts by weight of lubricant and 0.4 parts by weight of antioxidant.

8. A method for preparing a graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material, characterized in that, The method for preparing the graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material according to any one of claims 1 to 7 includes: Step (A-1): Mix nylon, flake graphite, aminated multi-arm carbon nanotubes, lubricant, and antioxidant evenly to obtain a mixture; Step (A-2): The mixture is extruded and granulated in a twin-screw extruder to obtain composite material particles; Step (A-3): The composite material particles are dried in a blower oven and then injection molded in an injection molding machine.

9. The method for preparing the graphite-carbon nanotube thermally conductive and electromagnetically shielding composite material according to claim 8, characterized in that, A toughening agent is also added in step (A-1).

10. The method for preparing the graphite-carbon nanotube thermally and electromagnetically shielding composite material according to claim 8, characterized in that, The preparation method of the aminated multi-arm carbon nanotubes includes the following steps: Step (B-1): Carboxylated multi-arm carbon nanotubes, sulfoxide and solvent are mixed and subjected to acyl chloride reaction to obtain acyl chloride multi-arm carbon nanotubes; Step (B-2): Acyl chloride multi-arm carbon nanotubes are mixed with an organic amine solution to carry out an amination reaction, thereby obtaining amination-treated multi-arm carbon nanotubes.

Images