Heat-conducting electromagnetic shielding carbon fiber-silicone rubber phase change composite material as well as preparation method and application thereof
By combining polyethylene glycol-polydopamine modified carbon fiber with a silicone rubber matrix and utilizing direct ink writing and printing technology to construct thermally and electrically conductive pathways, the problem that existing materials cannot simultaneously possess both thermal conductivity and electromagnetic shielding properties is solved, enabling the application of high-performance electromagnetic shielding materials.
Patent Information
- Application Number
- CN202511633924.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-10
- Publication Date
- 2026-02-27
AI Technical Summary
Existing electromagnetic shielding materials are difficult to combine excellent thermal conductivity and electromagnetic shielding performance, and cannot meet the problems of heat accumulation and electromagnetic interference brought about by the miniaturization and high frequency of electronic components.
Polyethylene glycol-polydopamine modified carbon fiber is composited with a silicone rubber matrix. Direct ink writing and printing technology is used to achieve a highly oriented arrangement of carbon fibers, constructing a continuous thermal and electrical conductive path. Combined with thermally conductive powder, the thermal conductivity and electromagnetic shielding performance of the material are improved.
A composite material with a thermal conductivity of 35.2 W·m⁻¹·K⁻¹ and an electromagnetic shielding effectiveness of 92.7 dB has been developed, which is suitable for 5G/6G communications, high-end chips, new energy vehicles, low-altitude aircraft and artificial intelligence.
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Figure CN121574557A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electromagnetic shielding technology, specifically to a thermally conductive electromagnetic shielding carbon fiber-silicone rubber phase change composite material, its preparation method, and its application. Background Technology
[0002] In recent years, with the rapid development of 5G / 6G communications, new energy vehicles, and artificial intelligence, electronic components have become increasingly miniaturized and higher frequency-controlled. However, due to space constraints and the complex electromagnetic environment, the miniaturization and high-frequency operation of electronic components exacerbate heat accumulation, leading to a rapid rise in component temperature and highlighting electromagnetic interference problems, severely affecting the stable operation and lifespan of electronic equipment. Electromagnetic shielding materials can mitigate electromagnetic interference and have a very broad application prospect in the field of electromagnetic shielding. However, most existing electromagnetic shielding materials cannot simultaneously possess excellent thermal conductivity and excellent electromagnetic shielding performance, making it difficult to fully meet the ever-increasing practical application requirements.
[0003] Therefore, developing an electromagnetic shielding material that combines excellent thermal conductivity and excellent electromagnetic shielding performance is of great significance. Summary of the Invention
[0004] The purpose of this invention is to provide a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material, its preparation method, and its application.
[0005] The technical solution adopted in this invention is: A thermally conductive and electromagnetically shielding carbon fiber-silicone rubber phase change composite material comprises a silicone rubber matrix, polyethylene glycol-polydopamine modified carbon fibers dispersed in the silicone rubber matrix, and thermally conductive powder dispersed in the silicone rubber matrix. The polyethylene glycol-polydopamine modified carbon fibers are oriented along the thickness direction in the silicone rubber matrix. The polyethylene glycol-polydopamine modified carbon fibers consist of carbon fibers, a polydopamine layer coating the carbon fibers, and polyethylene glycol grafted onto the surface of the polydopamine layer.
[0006] Preferably, the thermally conductive powder is at least one of spherical alumina, zinc oxide, hexagonal boron nitride, flake graphite, carbon nanotubes, and flake copper powder.
[0007] Preferably, the carbon fiber has a length of 100μm to 450μm and a diameter of 10μm to 15μm.
[0008] Preferably, the carbon fiber is pitch-based carbon fiber.
[0009] Preferably, the polyethylene glycol-polydopamine modified carbon fiber is prepared by a method comprising the following steps: a) Carbon fiber is dispersed in water to prepare a carbon fiber dispersion, then dopamine (DA) is added, and then tris(hydroxymethyl)aminomethane is added to adjust the pH of the system to 8-10 before polymerization reaction. Then the product is separated and dried to obtain polydopamine modified carbon fiber. b) Polydopamine-modified carbon fibers were dispersed in an aqueous dispersion of methoxy polyethylene glycol thiol (mPEG-SH), and sodium hydroxide was added to adjust the pH of the system to 8-10 before reacting at room temperature in the dark (reaction principle: catechol in polydopamine molecules is oxidized to o-benzoquinone under oxygen and alkaline conditions, and then methoxy polyethylene glycol thiol is grafted onto the surface of the polydopamine layer through Michael addition reaction). The products were then separated and dried to obtain polyethylene glycol-polydopamine-modified carbon fibers.
[0010] Preferably, the mass ratio of the carbon fiber in step a), the dopamine in step a), and the methoxy polyethylene glycol thiol in step b) is 1:0.3 to 1:2 to 5.
[0011] Preferably, the mass ratio of carbon fiber to water in step a) is 2 to 5:100.
[0012] Preferably, the concentration of the carbon fiber dispersion in step a) is 20 g / L to 40 g / L.
[0013] Preferably, the tris(hydroxymethyl)aminomethane in step a) is added in the form of an aqueous solution of tris(hydroxymethyl)aminomethane, and the concentration of the aqueous solution of tris(hydroxymethyl)aminomethane is 1.0 g / L to 1.5 g / L.
[0014] Preferably, the drying in step a) is carried out at a temperature of 60℃ to 100℃ for a drying time of 12h to 24h.
[0015] Preferably, the number-average molecular weight of the methoxy polyethylene glycol thiol in step b) is 3000 g / mol to 10000 g / mol.
[0016] Preferably, the sodium hydroxide in step b) is added in the form of an aqueous sodium hydroxide solution with a concentration of 1 mol / L to 3 mol / L.
[0017] Preferably, the drying in step b) is carried out at a temperature of 60℃ to 100℃ for a drying time of 12h to 24h.
[0018] Preferably, the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material comprises the following raw materials in parts by weight: Vinyl silicone oil: 100 parts; Hydrogen-containing silicone oil: 8 parts to 20 parts; Polyethylene glycol-polydopamine modified carbon fiber: 10 parts to 70 parts; Thermally conductive powder: 10 parts to 200 parts; Platinum catalyst: 1 to 2 parts; Inhibitor: 0.1 to 0.2 parts.
[0019] Preferably, the viscosity of the vinyl silicone oil is 100 mPa·s to 1000 mPa·s.
[0020] Preferably, the hydrogen content of the hydrogen-containing silicone oil is 0.10wt% to 0.25wt%.
[0021] Preferably, the platinum concentration of the platinum catalyst is 2000ppm to 3000ppm.
[0022] Preferably, the inhibitor is at least one selected from 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, and 3-methyl-1-pentyn-3-ol.
[0023] A method for preparing the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material as described above includes the following steps: 1) Mix vinyl silicone oil, hydrogen-containing silicone oil and inhibitor evenly and degas, then add polyethylene glycol-polydopamine modified carbon fiber, thermally conductive powder and platinum catalyst, mix evenly and degas again to obtain a mixed slurry; 2) The mixed slurry is injected into the direct ink writing and printing device, and then printed layer by layer along the set direction to obtain a carbon fiber-silicone rubber preform; 3) The carbon fiber-silicone rubber preform is vulcanized to obtain a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material.
[0024] Preferably, the degassing time in step 1) is 5 min to 30 min.
[0025] Preferably, the printing process parameters in step 2) include: the inner diameter of the printing needle is 0.8mm to 3.0mm, the printing air pump pressure is 10psi to 100psi, and the printing speed is 1mm / s to 40mm / s.
[0026] Preferably, the vulcanization in step 3) is carried out at a temperature of 80℃ to 120℃ for a vulcanization time of 0.5h to 6h.
[0027] Applications of a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material as described above in the fields of 5G / 6G communications, high-end chips, new energy vehicles, low-altitude aircraft, or artificial intelligence.
[0028] The beneficial effects of this invention are: the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of this invention has both excellent thermal conductivity and excellent electromagnetic shielding performance, and can be used in fields such as 5G / 6G communication, high-end chips, new energy vehicles, low-altitude aircraft and artificial intelligence. Moreover, its preparation method is simple and suitable for large-scale industrial production and application.
[0029] Specifically: 1) The thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of the present invention contains polyethylene glycol-polydopamine modified carbon fiber. The polyethylene glycol can play the role of phase change temperature control. Since the polyethylene glycol is grafted onto the polydopamine layer on the surface of the carbon fiber, the polyethylene glycol will be constrained by the carbon fiber during the melting process, thereby effectively avoiding the problem of leakage of phase change thermal conductive material from the silicone rubber matrix. 2) This invention employs Direct Ink Writing (DIW) printing technology to achieve highly oriented alignment of polyethylene glycol-polydopamine modified carbon fibers through confined extrusion (the mixed slurry has good printing fluidity, and the polyethylene glycol-polydopamine modified carbon fibers are oriented along the printing direction due to shear force). This constructs continuous and complete thermal and electrical conduction pathways within the composite material, significantly improving its thermal conductivity and electromagnetic shielding performance (the thermal conductivity can reach up to 35.2 W·m). -1 ·K -1 The electromagnetic shielding effectiveness can reach up to 92.7 dB. 3) The thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of the present invention has both excellent thermal conductivity and excellent electromagnetic shielding performance, and can be used in fields such as 5G / 6G communication, high-end chips, new energy vehicles, low-altitude aircraft and artificial intelligence, and has a very broad application prospect. Attached Figure Description
[0030] Figure 1 This is a flowchart illustrating the preparation process of polyethylene glycol-polydopamine modified carbon fiber in this invention.
[0031] Figure 2 This is a flowchart illustrating the preparation process of the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of the present invention.
[0032] Figure 3 This is a physical image of the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of Example 1.
[0033] Figure 4 This is a SEM image of the cross section of the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of Example 1.
[0034] Figure 5 The image shows a cross-section of the carbon fiber-silicone rubber composite material in Comparative Example 1 using SEM.
[0035] Figure 6 The images show the XRD patterns of the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite materials of Examples 1, 3, and 4, and the carbon fiber-silicone rubber composite material of Comparative Example 1.
[0036] Figure 7 The electromagnetic shielding effectiveness of the thermally conductive and electromagnetically shielding carbon fiber-silicone rubber phase change composite materials in the X-band varies with frequency, as shown in Examples 2, 3, and 5. Detailed Implementation
[0037] The present invention will be further explained and described below with reference to specific embodiments.
[0038] Example 1: A thermally conductive and electromagnetically shielding carbon fiber-silicone rubber phase change composite material, the raw materials for which it is prepared are shown in the table below: Table 1. Raw material list for the preparation of a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material.
[0039] Note: The preparation method of polyethylene glycol-polydopamine modified carbon fiber is as follows (preparation process as follows). Figure 1 (as shown) a) Pitch-based carbon fibers (150 μm in length and 10 μm in diameter) were ultrasonically dispersed in deionized water to prepare a carbon fiber dispersion with a concentration of 30 g / L. Dopamine was then added, with a mass ratio of pitch-based carbon fibers to dopamine of 1:0.5. The pH of the system was adjusted to 8.5 by adding a 1.2 g / L aqueous solution of tris(hydroxymethyl)aminomethane. The mixture was stirred for 12 h at a stirring rate of 400 rpm, filtered, and the solid was dried at 80 °C for 24 h to obtain polydopamine-modified carbon fibers (denoted as PDA@CF). b) Polydopamine-modified carbon fiber was ultrasonically dispersed in an aqueous dispersion of methoxy polyethylene glycol thiol (number average molecular weight 5000 g / mol) with a concentration of 90 g / L. The mass ratio of pitch-based carbon fiber to methoxy polyethylene glycol thiol was 1:3. A 1 mol / L sodium hydroxide aqueous solution was added to adjust the pH of the system to 8.0. The reaction was then stirred at room temperature in the dark for 12 h at a stirring rate of 400 rpm. After filtration, the solid was dried at 80 °C for 24 h to obtain polyethylene glycol-polydopamine-modified carbon fiber (denoted as PEG-PDA@CF).
[0040] The preparation method of the above-mentioned thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material is as follows (the preparation process is as follows). Figure 2 (as shown) 1) Mix vinyl silicone oil, hydrogen-containing silicone oil and 1-ethynyl-1-cyclohexanol, stir at high speed for 5 minutes at a stirring rate of 2000 rpm, then degas under vacuum for 5 minutes, then add polyethylene glycol-polydopamine modified carbon fiber, sheet graphite and cassiterite catalyst, continue stirring for 5 minutes, then degas under vacuum for 5 minutes to obtain a mixed slurry. 2) The mixed slurry is injected into the direct ink writing and printing device and printed layer by layer in the set direction. The printing process parameters are as follows: the inner diameter of the printing needle is 1.36 mm, the printing air pump pressure is 20 psi, and the printing speed is 26 mm / s, to obtain a carbon fiber-silicone rubber preform. 3) The carbon fiber-silicone rubber preform was vulcanized at 100℃ for 4 hours to obtain a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material (see physical image). Figure 3 (As shown).
[0041] The scanning electron microscope (SEM) image of the cross-section of the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material in this embodiment is shown below. Figure 4 As shown.
[0042] Depend on Figure 4 It can be seen that the polyethylene glycol-polydopamine modified carbon fibers are highly oriented along the thickness direction in the silicone rubber matrix, indicating that DIW printing can indeed prepare carbon fiber-silicone rubber phase change composite materials with the expected microstructure.
[0043] Example 2: A thermally conductive and electromagnetically shielding carbon fiber-silicone rubber phase change composite material, the raw materials for which it is prepared are shown in the table below: Table 2. Raw material list for the preparation of a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material.
[0044] The preparation method of the above-mentioned thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material is as follows (the preparation process is as follows). Figure 2 (as shown) 1) Mix vinyl silicone oil, hydrogen-containing silicone oil and 1-ethynyl-1-cyclohexanol, stir at high speed for 5 minutes at a stirring rate of 2000 rpm, then degas under vacuum for 5 minutes, then add polyethylene glycol-polydopamine modified carbon fiber, spherical alumina and cassiterite catalyst, continue stirring for 5 minutes, then degas under vacuum for 5 minutes to obtain a mixed slurry. 2) The mixed slurry is injected into the direct ink writing and printing device and printed layer by layer in the set direction. The printing process parameters are as follows: the inner diameter of the printing needle is 1.36 mm, the printing air pump pressure is 20 psi, and the printing speed is 26 mm / s, to obtain a carbon fiber-silicone rubber preform. 3) The carbon fiber-silicone rubber preform was vulcanized at 100℃ for 4 hours to obtain a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material.
[0045] Example 3: A thermally conductive and electromagnetically shielding carbon fiber-silicone rubber phase change composite material, the raw materials for which it is prepared are shown in the table below: Table 3. Raw material list for the preparation of a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material.
[0046] Note: The preparation method of polyethylene glycol-polydopamine modified carbon fiber is as follows (preparation process as follows). Figure 1 (as shown) a) Pitch-based carbon fibers (250 μm in length and 10 μm in diameter) were ultrasonically dispersed in deionized water to prepare a carbon fiber dispersion with a concentration of 30 g / L. Dopamine was then added, with a mass ratio of pitch-based carbon fibers to dopamine of 1:0.5. The pH of the system was adjusted to 8.5 by adding a 1.2 g / L aqueous solution of tris(hydroxymethyl)aminomethane. The mixture was stirred for 12 h at a stirring rate of 400 rpm, filtered, and the solid was dried at 80 °C for 24 h to obtain polydopamine-modified carbon fibers (denoted as PDA@CF). b) Polydopamine-modified carbon fiber was ultrasonically dispersed in an aqueous dispersion of methoxy polyethylene glycol thiol (number average molecular weight 5000 g / mol) with a concentration of 90 g / L. The mass ratio of pitch-based carbon fiber to methoxy polyethylene glycol thiol was 1:3. A 1 mol / L sodium hydroxide aqueous solution was added to adjust the pH of the system to 8.0. The reaction was then stirred at room temperature in the dark for 12 h at a stirring rate of 400 rpm. After filtration, the solid was dried at 80 °C for 24 h to obtain polyethylene glycol-polydopamine-modified carbon fiber (denoted as PEG-PDA@CF).
[0047] The preparation method of the above-mentioned thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material is as follows (the preparation process is as follows). Figure 2 (as shown) 1) Mix vinyl silicone oil, hydrogen-containing silicone oil and 1-ethynyl-1-cyclohexanol, stir at high speed for 5 minutes at a stirring rate of 2000 rpm, then degas under vacuum for 5 minutes, then add polyethylene glycol-polydopamine modified carbon fiber, sheet graphite and cassiterite catalyst, continue stirring for 5 minutes, then degas under vacuum for 5 minutes to obtain a mixed slurry. 2) The mixed slurry is injected into the direct ink writing and printing device and printed layer by layer in the set direction. The printing process parameters are as follows: the inner diameter of the printing needle is 2.00 mm, the printing air pump pressure is 30 psi, and the printing speed is 26 mm / s, to obtain a carbon fiber-silicone rubber preform. 3) The carbon fiber-silicone rubber preform was vulcanized at 100℃ for 4 hours to obtain a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material.
[0048] Example 4: A thermally conductive and electromagnetically shielding carbon fiber-silicone rubber phase change composite material, the raw materials for which it is prepared are shown in the table below: Table 4. Raw material list for the preparation of a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material.
[0049] The preparation method of the above-mentioned thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material is as follows (the preparation process is as follows). Figure 2 (as shown) 1) Mix vinyl silicone oil, hydrogen-containing silicone oil and 1-ethynyl-1-cyclohexanol, stir at high speed for 5 minutes at a stirring rate of 2000 rpm, then degas under vacuum for 5 minutes, then add polyethylene glycol-polydopamine modified carbon fiber, sheet graphite and cassiterite catalyst, continue stirring for 5 minutes, then degas under vacuum for 5 minutes to obtain a mixed slurry. 2) The mixed slurry is injected into the direct ink writing and printing device and printed layer by layer in the set direction. The printing process parameters are as follows: the inner diameter of the printing needle is 1.36 mm, the printing air pump pressure is 30 psi, and the printing speed is 26 mm / s, to obtain a carbon fiber-silicone rubber preform. 3) The carbon fiber-silicone rubber preform was vulcanized at 100℃ for 4 hours to obtain a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material.
[0050] Example 5: A thermally conductive and electromagnetically shielding carbon fiber-silicone rubber phase change composite material, the raw materials for which it is prepared are shown in the table below: Table 5. Raw material list for the preparation of a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material.
[0051] The preparation method of the above-mentioned thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material is as follows (the preparation process is as follows). Figure 2 (as shown) 1) Mix vinyl silicone oil, hydrogen-containing silicone oil and 1-ethynyl-1-cyclohexanol, stir at high speed for 5 minutes at a stirring rate of 2000 rpm, then degas under vacuum for 5 minutes, then add polyethylene glycol-polydopamine modified carbon fiber, sheet graphite and cassiterite catalyst, continue stirring for 5 minutes, then degas under vacuum for 5 minutes to obtain a mixed slurry. 2) The mixed slurry is injected into the direct ink writing and printing device and printed layer by layer in the set direction. The printing process parameters are as follows: the inner diameter of the printing needle is 1.36 mm, the printing air pump pressure is 60 psi, and the printing speed is 26 mm / s, to obtain a carbon fiber-silicone rubber preform. 3) The carbon fiber-silicone rubber preform was vulcanized at 120℃ for 6 hours to obtain a thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material.
[0052] Comparative Example 1: A carbon fiber-silicone rubber composite material, the raw materials for which it is prepared are shown in the table below: Table 6. Raw material list for the preparation of a carbon fiber-silicone rubber composite material
[0053] The preparation method of the above carbon fiber-silicone rubber composite material is as follows: 1) Mix vinyl silicone oil, hydrogen-containing silicone oil and 1-ethynyl-1-cyclohexanol, stir at high speed for 5 minutes at a stirring rate of 2000 rpm, then degas under vacuum for 5 minutes, then add pitch-based carbon fiber and cassiterite catalyst, continue stirring for 5 minutes, then degas under vacuum for 5 minutes to obtain a mixed slurry. 2) Inject the mixed slurry into a silicone mold, and then place it in a vacuum drying oven for 20 minutes to degas, thereby obtaining a carbon fiber-silicone rubber preform; 3) The carbon fiber-silicone rubber preform was vulcanized at 100℃ for 3 hours to obtain the carbon fiber-silicone rubber composite material.
[0054] The SEM image of the cross-section of the carbon fiber-silicone rubber composite material in this comparative example is shown below. Figure 5 As shown.
[0055] Depend on Figure 5 It can be seen that the carbon fibers in the carbon fiber-silicone rubber composite material are not oriented.
[0056] Comparative Example 2: A carbon fiber-silicone rubber composite material, the raw materials for which it is prepared are shown in the table below: Table 7. Raw material list for the preparation of a carbon fiber-silicone rubber composite material
[0057] The preparation method of the above carbon fiber-silicone rubber composite material is as follows: 1) Mix vinyl silicone oil, hydrogen-containing silicone oil and 1-ethynyl-1-cyclohexanol, stir at high speed for 5 minutes at a stirring rate of 2000 rpm, then degas under vacuum for 5 minutes, then add pitch-based carbon fiber and cassiterite catalyst, continue stirring for 5 minutes, then degas under vacuum for 5 minutes to obtain a mixed slurry. 2) The mixed slurry is injected into the direct ink writing and printing device and printed layer by layer in the set direction. The printing process parameters are as follows: the inner diameter of the printing needle is 1.36 mm, the printing air pump pressure is 20 psi, and the printing speed is 26 mm / s, to obtain a carbon fiber-silicone rubber preform. 3) The carbon fiber-silicone rubber preform was vulcanized at 100℃ for 4 hours to obtain the carbon fiber-silicone rubber composite material.
[0058] Performance testing: 1) X-ray diffraction (XRD) patterns of the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite materials of Examples 1, 3, and 4, and the carbon fiber-silicone rubber composite material of Comparative Example 1 are shown below. Figure 6 (a is the XRD pattern, b is the I) （100） / I （100+002） (As shown in the numerical graph).
[0059] Depend on Figure 6 It can be seen that the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite materials of Examples 1, 3, and 4 correspond to I. （100） / I （100+002） The values are all higher than those corresponding to the carbon fiber-silicone rubber composite material in Comparative Example 1, indicating that the carbon fiber orientation degree of the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite materials in Examples 1, 3, and 4 is higher (I （100） / I （100+002） The numerical value indicates the degree of orientation of the carbon fibers; the larger the value, the higher the degree of orientation of the carbon fibers.
[0060] 2) The electromagnetic shielding effectiveness of the thermally conductive and electromagnetically shielding carbon fiber-silicone rubber phase change composite materials in the X-band of Examples 2, 3, and 5 varies with frequency as shown in the curves. Figure 7 As shown.
[0061] Depend on Figure 7 It can be seen that the electromagnetic shielding efficiency of the thermally conductive and electromagnetically shielding carbon fiber-silicone rubber phase change composite material in Example 5 is as high as 92.7dB, which has excellent electromagnetic shielding effect.
[0062] 3) The test results of thermal conductivity and electromagnetic shielding properties of the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite materials of Examples 1-5 and the carbon fiber-silicone rubber composite materials of Comparative Examples 1-2 are shown in the table below: Table 8 Test results of thermal conductivity and electromagnetic shielding performance
[0063] Note: Thermal conductivity: The test was conducted using a thermal constant analyzer, referring to "ISO 22007-2:2008 Determination of thermal conductivity and thermal diffusivity of plastics - Part 2: Transient planar heat source (heating plate) method" and "GB / T 32064-2015 Thermal conductivity and thermal diffusivity of building materials - Transient planar heat source test method". The sample size was 25mm×25mm×20mm (block) to ensure that the sample was in close contact with the probe.
[0064] Electromagnetic shielding effectiveness: The electromagnetic parameters of the sample in the X-band (8.2 GHz to 12.4 GHz) were tested using a vector network analyzer. The test method was waveguide method. The sample size was 22.86 mm × 10.16 mm × 2.00 mm.
[0065] Phase transition enthalpy: The phase transition enthalpy of the sample was calculated using DSC analysis.
[0066] As shown in Table 8: 1) The thermal conductivity of the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite materials in Examples 1 to 5 is significantly improved compared with that of the carbon fiber-silicone rubber composite materials in Comparative Examples 1 and 2. The reasons are: a) The shearing and orientation effect of DIW printing on carbon fibers makes the carbon fibers oriented along the thickness direction, which helps to build thermal conductivity pathways; b) Thermally conductive powder can effectively improve the thermal conductivity of composite materials. 2) Compared with the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of Example 1, the phase change enthalpy of the composite material is increased due to the increased carbon fiber filling amount in Example 2. 3) Compared with the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of Example 1, the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of Example 3 has a longer thermal conductivity due to the use of longer CF to construct a longer thermal conductivity path, fewer CF overlap sites, and lower total thermal resistance. Under the same CF dosage, the composite material has a higher thermal conductivity. At the same time, due to the more complete conductive path, the electromagnetic shielding performance of the composite material is also higher. 4) Compared with the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of Example 3, the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of Example 4 has a better orientation effect on CF due to the use of a printing needle with a smaller inner diameter, and the composite material has a higher thermal conductivity. 5) Compared with the thermally conductive and electromagnetically shielded carbon fiber-silicone rubber phase change composite material of Example 4, the thermal conductivity and electromagnetic shielding performance of the composite material of Example 5 are improved due to the increased carbon fiber filling amount.
[0067] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A thermally conductive electromagnetic shielding carbon fiber-silicone rubber phase change composite material, characterized in that, The composition comprises a silicone rubber matrix, polyethylene glycol-polydopamine modified carbon fibers dispersed in the silicone rubber matrix, and thermally conductive powder dispersed in the silicone rubber matrix; the polyethylene glycol-polydopamine modified carbon fibers are arranged in the silicone rubber matrix in the thickness direction; the polyethylene glycol-polydopamine modified carbon fibers comprise carbon fibers, a polydopamine layer covering the carbon fibers, and polyethylene glycol grafted on the surface of the polydopamine layer.
2. The thermally-conductive, electromagnetically-shielded carbon fiber-silicone rubber phase change composite of claim 1, wherein: The thermally conductive powder is at least one of spherical aluminum oxide, zinc oxide, hexagonal boron nitride, flaky graphite, carbon nanotubes, and flaky copper powder.
3. The thermally-conductive, electromagnetically-shielded carbon fiber-silicone rubber phase change composite of claim 1, wherein: The length of the carbon fibers is 100 μm to 450 μm, and the diameter is 10 μm to 15 μm.
4. The thermally-conductive, electromagnetically-shielded carbon fiber-silicone rubber phase change composite of claim 1, wherein: The polyethylene glycol-polydopamine modified carbon fibers are prepared by a preparation method comprising the following steps: a) dispersing carbon fibers in water to obtain a carbon fiber dispersion, then adding dopamine, adjusting the pH of the system to 8 to 10 by adding trimethylol aminomethane, and then performing polymerization, followed by product separation and drying to obtain polydopamine modified carbon fibers; b) dispersing the polydopamine modified carbon fibers in a water dispersion of methoxypolyethylene glycol thiol, then adding sodium hydroxide to adjust the pH of the system to 8 to 10, and then performing room temperature light-free reaction, followed by product separation and drying to obtain polyethylene glycol-polydopamine modified carbon fibers.
5. The thermally-conductive, electromagnetically-shielded carbon fiber-silicone rubber phase change composite of claim 4, wherein: The mass ratio of the carbon fibers in step a), the dopamine in step a), and the methoxypolyethylene glycol thiol in step b) is 1:0.3 to 1:2 to 5.
6. The thermally-conductive, electromagnetically-shielded carbon fiber-silicone rubber phase change composite of any one of claims 1-5, wherein: The thermally conductive electromagnetic shielding carbon fiber-silicone rubber phase change composite material comprises the following mass fractions of raw materials: vinyl silicone oil: 100 parts; hydrogen-containing silicone oil: 8 to 20 parts; polyethylene glycol-polydopamine modified carbon fibers: 10 to 70 parts; thermally conductive powder: 10 to 200 parts; platinum catalyst: 1 to 2 parts; inhibitor: 0.1 to 0.2 parts.
7. The thermally-conductive, electromagnetically-shielded carbon fiber-silicone rubber phase change composite of claim 6, wherein: The viscosity of the vinyl silicone oil is 100 mPa·s to 1000 mPa·s; the hydrogen content of the hydrogen-containing silicone oil is 0.10 wt% to 0.25 wt%; the platinum concentration of the platinum catalyst is 2000 ppm to 3000 ppm; and the inhibitor is at least one of 1-ethynyl-1-cyclohexanol, 2-methyl-3-butyn-2-ol, 3,5-dimethyl-1-hexyn-3-ol, and 3-methyl-1-pentyn-3-ol.
8. A method of producing the thermally conductive electromagnetic shielding carbon fiber-silicone rubber phase change composite material as claimed in claim 6 or 7, characterized by, The method comprises the following steps: 1) mixing the vinyl silicone oil, the hydrogen-containing silicone oil, and the inhibitor uniformly and degassing, then adding the polyethylene glycol-polydopamine modified carbon fibers, the thermally conductive powder, and the platinum catalyst, mixing uniformly and degassing to obtain a mixed slurry; 2) injecting the mixed slurry into a direct ink writing and printing device, then printing layer by layer along a set direction to obtain a carbon fiber-silicone rubber blank; 3) vulcanizing the carbon fiber-silicone rubber blank to obtain the thermally conductive electromagnetic shielding carbon fiber-silicone rubber phase change composite material.
9. The method of claim 8, wherein: Step 2) the printing process parameters include: the printing needle inner diameter is 0.8mm-3.0mm, the printing air pump pressure is 10psi-100psi, and the printing speed is 1mm / s-40mm / s; Step 3) the vulcanization is carried out at a temperature of 80℃-120℃, and the vulcanization time is 0.5h-6h.
10. Application of the heat-conducting electromagnetic shielding carbon fiber-silicone rubber phase change composite material in the 5G / 6G communication field, high-end chip field, new energy vehicle field, low-altitude aircraft field or artificial intelligence field according to any one of claims 1-7.