A high thermal conductivity composite film and its preparation method and application

Abstract

The present invention relates to the field of Joule heating technology, and in particular to a high thermal conductivity composite film, a preparation method thereof, and an application thereof. The preparation method provided by the present invention comprises the following steps: blending hydroxyl-modified poly(p-phenylene benzobisoxazole) fiber and polyetheretherketone fiber to obtain PBO-OH / PEEK fiber cloth; mixing a soluble polyetheretherketone solution, NH2-MWCNTs, and GnPs, and ultrasonicating to obtain a spraying liquid; using an electrostatic spraying method, spraying the spraying liquid on the upper and lower surfaces of the PBO-OH / PEEK fiber cloth, and hot pressing to obtain the high thermal conductivity composite film. The high thermal conductivity composite film prepared by the preparation method has excellent mechanical properties as well as excellent in-plane thermal conductivity, electrical conductivity, and electromagnetic shielding effect.

Description

Technical Field

[0001] The present invention relates to the technical field of Joule heating, and in particular to a high thermal conductivity composite film and a preparation method and application thereof. Background Art

[0002] In recent years, Joule heating technology has been widely studied and applied to meet a wider range of thermal comfort needs. Joule heaters based on polymer-based composite membrane materials are typically fabricated by adding a conductive material (both thermally and electrically conductive) to a polymer matrix, forming a percolating network capable of resistive heating. However, Joule heating typically responds quickly and can easily lead to overheating. Therefore, the design of conductive materials requires consideration of both the thermal conductivity of the material to achieve effective heat dissipation and the control of electrical resistance to optimize Joule heating generation and management. Carbon materials, with their high thermal conductivity, can effectively dissipate Joule-generated heat, thereby preventing overheating of materials or devices, sparking significant research interest. Their thermal conductivity primarily relies on the transport of phonons and electrons within the material. The high mobility of electrons makes the electron collision-based heat transfer mechanism more efficient, resulting in excellent thermal and electrical conductivity. However, to achieve Joule heating performance, carbon materials typically require very high filler loadings, significantly increasing manufacturing costs. Therefore, reducing manufacturing costs without compromising electrical and thermal conductivity is a widespread concern.

[0003] Research has shown that the synergistic effect of multi-scale fillers and the "bridging" nanostructure can significantly enhance the electrical and thermal conductivity of materials. Polyetheretherketone (PEEK) is widely used in aerospace, military, and machinery due to its excellent thermal stability, lightweight, high mechanical properties, and good chemical resistance. However, due to the disordered vibration of PEEK's molecular weight and the low-speed phonon diffusion, its thermal conductivity is low, which greatly limits its performance improvement in certain applications. Summary of the Invention

[0004] The object of the present invention is to provide a high thermal conductivity composite film and its preparation method and application. The high thermal conductivity composite film prepared by the preparation method has excellent electromagnetic shielding performance while also having excellent in-plane thermal conductivity, electrical conductivity and Joule heating effect.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a high thermal conductivity composite film, comprising the following steps:

[0007] The hydroxyl-modified poly (p-phenylene benzobisoxazole) fiber and poly (ether ether ketone) fiber are blended to obtain PBO-OH / PEEK fiber cloth;

[0008] After mixing the soluble polyetheretherketone solution, NH2-MWCNTs and GnPs, ultrasonication was performed to obtain a spraying solution;

[0009] The high thermal conductivity composite film is obtained by spraying the spraying liquid on the upper and lower surfaces of the PBO-OH / PEEK fiber cloth in an electrostatic spraying manner and then hot pressing.

[0010] Preferably, the preparation method of the hydroxyl-modified poly(p-phenylene benzobisoxazole) fiber comprises: subjecting the poly(p-phenylene benzobisoxazole) fiber to plasma treatment to obtain the hydroxyl-modified poly(p-phenylene benzobisoxazole) fiber;

[0011] The plasma used in the plasma treatment is a mixed plasma of oxygen and argon with a pressure ratio of (2-4): (1-3); the input power of the plasma treatment is 100-200W, and the time is 10-20 minutes.

[0012] Preferably, the concentration of the soluble polyetheretherketone in the soluble polyetheretherketone solution is 3 to 10 mg / mL, and the polyetheretherketone is a fluorinated polyetheretherketone;

[0013] The solvents in the soluble polyetheretherketone solution are N-methylpyrrolidone and dichloromethane; the volume ratio of the N-methylpyrrolidone to dichloromethane is (1-3): (9-7).

[0014] Preferably, the mass ratio of the NH2-MWCNTs to the GnPs is (1-9): (9-1);

[0015] The total concentration of NH2-MWCNTs and GnPs in the spraying liquid is 5 mg / mL.

[0016] Preferably, the frequency of the ultrasound is 20 to 30 kHz, and the duration is 20 to 40 minutes.

[0017] Preferably, the spraying voltage is 40-60 kV, and the distance between the nozzle and the PBO-OH / PEEK fiber cloth is 20-40 cm.

[0018] Preferably, the hot pressing temperature is 360-380° C., the pressure is 10-50 MPa, and the holding time is 10-20 min.

[0019] Preferably, the total mass percentage of NH2-MWCNTs and GnPs in the high thermal conductivity composite film is 5 to 35%.

[0020] The present invention also provides a high thermal conductivity composite film prepared by the preparation method described in the above technical solution.

[0021] The present invention also provides the application of the high thermal conductivity composite film described in the above technical solution in the field of smart wearable electronics or medical devices.

[0022] The present invention provides a method for preparing a high-thermal-conductivity composite film, comprising the following steps: blending hydroxyl-modified poly(p-phenylene benzobisoxazole) fiber and polyetheretherketone fiber to obtain a PBO-OH / PEEK fiber cloth; mixing a soluble polyetheretherketone solution, NH2-MWCNTs, and GnPs, and ultrasonically treating the mixture to obtain a spraying liquid; and electrostatically spraying the spraying liquid on the upper and lower surfaces of the PBO-OH / PEEK fiber cloth, followed by hot pressing to obtain the high-thermal-conductivity composite film. The poly(p-phenylene benzobisoxazole) fiber (PBO) in the preparation method of the present invention has excellent mechanical properties and a unique one-dimensional structure. By minimizing the interfacial thermal resistance and forming a well-arranged structure, it is possible to prepare a high thermal conductivity composite film with Joule heating performance, high thermal conductivity and good mechanical properties. Furthermore, the present invention modifies PBO with hydroxyl groups and uses electrostatic spraying technology to coat amino-modified carbon nanotubes and graphene nanosheets on the surface of PBO-OH / PEEK fiber cloth, successfully preparing a high thermal conductivity composite film for intelligent thermal management electronic sensing. The grid structure of the PBO-OH / PEEK fiber cloth in the high thermal conductivity composite film also provides multiple interfaces for the scattering and reflection of incident electromagnetic waves, thereby improving the shielding efficiency. The high thermal conductivity composite film prepared by the preparation method exhibits excellent in-plane thermal conductivity, electrical conductivity and electromagnetic shielding effectiveness, and exhibits good Joule heating and physiological signal monitoring functions. It not only provides a reference for the forward-looking application of traditional polymer-based materials, but also contributes to the development of future smart homes. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of the PBO-OH / PEEK fiber cloth of the present invention;

[0024] Figure 2 The in-plane thermal conductivity and out-of-plane thermal conductivity of the high thermal conductivity composite films of Examples 1 to 7(b) and Comparative Examples 1 to 7(a) and their corresponding thermal conductivity enhancement graphs;

[0025] Figure 3 The electrical conductivity of the high thermal conductivity composite film described in Examples 1 to 7;

[0026] Figure 4 The electromagnetic shielding performance of the high thermal conductivity composite film described in Examples 1 to 7;

[0027] Figure 5 This is a graph showing the change in the relative resistance value (ΔR / R0) of the high thermal conductive composite film described in Example 7 as the finger is stretched and then bent. DETAILED DESCRIPTION

[0028] The present invention provides a method for preparing a high thermal conductivity composite film, comprising the following steps:

[0029] The hydroxyl-modified poly (p-phenylene benzobisoxazole) fiber and poly (ether ether ketone) fiber are blended to obtain PBO-OH / PEEK fiber cloth;

[0030] After mixing the soluble polyetheretherketone solution, NH2-MWCNTs and GnPs, ultrasonication was performed to obtain a spraying solution;

[0031] The high thermal conductivity composite film is obtained by spraying the spraying liquid on the upper and lower surfaces of the PBO-OH / PEEK fiber cloth in an electrostatic spraying manner and then hot pressing.

[0032] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0033] The invention blends hydroxyl-modified poly (p-phenylene benzobisoxazole) fiber (PBO-OH) and polyetheretherketone fiber to obtain PBO-OH / PEEK fiber cloth.

[0034] In the present invention, the preparation method of the hydroxy-modified poly(p-phenylene benzobisoxazole) fiber preferably comprises: subjecting the poly(p-phenylene benzobisoxazole) fiber to a plasma treatment to obtain the hydroxy-modified poly(p-phenylene benzobisoxazole) fiber; the plasma used for the plasma treatment is preferably a mixed plasma of oxygen and argon with a pressure ratio of (2 to 4): (1 to 3), more preferably a mixed plasma of oxygen and argon with a pressure ratio of 3:2; the input power of the plasma treatment is preferably 100 to 200 W, more preferably 150 W, and the time is preferably 10 to 20 min, more preferably 15 min. Before performing the plasma treatment, the present invention also preferably comprises soaking and drying the poly(p-phenylene benzobisoxazole) fiber in sequence; the soaking is preferably soaking in acetone and deionized water for 24 hours each. In the present invention, the drying is preferably vacuum drying; the temperature of the vacuum drying is preferably 80 to 105°C, more preferably 105°C, and the time of the vacuum drying is preferably 2 to 5 hours, more preferably 3 hours. In the present invention, the soaking and drying process can remove sizing agents and contaminants from the surface of the PBO fiber. In the present invention, the plasma treatment process preferably involves placing the dried PBO fiber in a vacuum plasma cleaning machine for treatment. After placing the PBO fiber in a vacuum chamber, the vacuum pump is turned on to reduce the pressure in the vacuum chamber to 2-3 Pa. Plasma gas is then introduced, and the pressure in the vacuum chamber is controlled by the flow rate of the gas flow valve. The vacuum chamber pressure is maintained at 40 Pa, and the plasma treatment is performed for 15 minutes at an input power of 150 W.

[0035] In the present invention, functional groups such as hydroxyl groups in the hydroxyl-modified poly(p-phenylene benzobisoxazole) fibers form hydrogen bonds with amino groups of NH2-MWCNTs. In addition, the introduction of polar groups such as carboxyl groups, hydroxyl groups and amide groups on the surface of PBO fibers is beneficial to improving the chemical bonding between PBO fibers and PEEK.

[0036] In the present invention, the mass ratio of the hydroxyl-modified poly(p-phenylene benzobisoxazole) fiber (PBO-OH) to the polyetheretherketone fiber is preferably (1-9):(9-1), more preferably (2-8):(8-2), and most preferably 8:2.

[0037] In the present invention, the blended fabric is preferably woven in a plain weave, with the PBO-OH fiber as the warp yarn and the PEEK fiber as the weft yarn, interwoven one above and one below (such as Figure 1 shown)

[0038] The preparation method of the present invention further comprises mixing a soluble polyetheretherketone solution, NH2-MWCNTs and GnPs, and then ultrasonicating to obtain a spraying liquid.

[0039] In the present invention, the concentration of the soluble polyetheretherketone in the soluble polyetheretherketone solution is preferably 3-10 mg / mL, more preferably 3-8 mg / mL, and most preferably 3 mg / mL. The polyetheretherketone is preferably fluorinated polyetheretherketone; the solvent in the soluble polyetheretherketone solution is preferably N-methylpyrrolidone and dichloromethane; the volume ratio of the N-methylpyrrolidone and dichloromethane is preferably (1-3): (9-7), more preferably 1:8.

[0040] In the present invention, the mass ratio of NH2-MWCNTs and GnPs is preferably (1-9): (9-1), more preferably 2:8; the total concentration of NH2-MWCNTs and GnPs in the spraying liquid is preferably 1-5 mg / mL, more preferably 5 mg / mL.

[0041] The present invention does not have any special limitation on the mixing process, and the mixing process may be carried out using a process well known to those skilled in the art.

[0042] In the present invention, the frequency of the ultrasound is preferably 20 to 30 KHz, more preferably 20 KHz; the time is preferably 20 to 40 min, more preferably 30 min.

[0043] After obtaining the spraying liquid and PBO-OH / PEEK fiber cloth, the present invention adopts electrostatic spraying to spray the spraying liquid on the upper and lower surfaces of the PBO-OH / PEEK fiber cloth, and then hot presses to obtain the high thermal conductivity composite film.

[0044] In the present invention, the spraying voltage is preferably 40-60 kV, more preferably 60 kV; the distance between the nozzle and the PBO-OH / PEEK fiber cloth is preferably 20-40 cm, more preferably 20 cm. In an embodiment of the present invention, the spraying equipment is provided by Dongguan Taiben Automation Equipment Co., Ltd.; the specific spraying conditions are: under grounding conditions, the spraying voltage is set to 40-60 kV, the distance between the nozzle and the PBO-OH / PEEK fiber cloth fixed on a uniformly rotating roller is 20-40 cm, and the nozzle flow rate is controlled by adjusting the rear knob of the spray gun (High mode) to obtain a good electrostatic atomization effect.

[0045] In the present invention, the hot pressing temperature is preferably 360-380° C., more preferably 380° C.; the pressure is preferably 10-50 MPa, more preferably 30 MPa; and the holding time is preferably 10-20 min, more preferably 15 min.

[0046] After the hot pressing is completed, the present invention further preferably includes sequentially performing pressure removal and cooling. The present invention does not have any special limitation on the process of pressure removal, and the process well known to those skilled in the art can be used.

[0047] The present invention does not have any special limitation on the cooling process, and the cooling process may be carried out using a process well known to those skilled in the art.

[0048] In the present invention, the total mass percentage of NH2-MWCNTs and GnPs in the high thermal conductivity composite film is preferably 5-35%, more preferably 10-30%, and most preferably 15-25%. In embodiments of the present invention, the total mass percentage of NH2-MWCNTs and GnPs in the high thermal conductivity composite film can be 5%, 10%, 15%, 20%, 25%, 30%, or 35%.

[0049] The present invention also provides a high thermal conductivity composite film prepared by the preparation method described in the above technical solution.

[0050] The present invention also provides the use of the high thermal conductivity composite film described in the above technical solution in the field of smart wearable electronics or medical devices. The present invention does not have any special restrictions on the method of the application, and the method can be carried out using a process familiar to those skilled in the art.

[0051] The high thermal conductivity composite film provided by the present invention, its preparation method and application are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0052] Examples 1 to 7

[0053] The poly(p-phenylene benzobisoxazole) fiber was soaked in acetone and deionized water for 24 hours respectively, and then vacuum dried at 105°C for 3 hours. The dried PBO fiber was then placed in a vacuum plasma cleaning machine for treatment. After the PBO fiber was placed in a vacuum chamber, the vacuum pump was turned on to reduce the pressure of the vacuum chamber to 2-3 Pa. Then, plasma gas (a mixed plasma of oxygen and nitrogen with a pressure ratio of 3:2) was passed through the vacuum chamber. The pressure of the vacuum chamber was controlled by the flow rate of the gas flow valve, and the vacuum chamber pressure was maintained at 40 Pa. The input power was 150 W and the plasma treatment was carried out for 15 minutes to obtain PBO-OH fiber.

[0054] A plain weave was used, with the PBO-OH fiber as the warp yarn and the PEEK fiber as the weft yarn, interweaving alternately up and down to obtain a PBO-OH / PEEK fiber cloth (the mass ratio of PBO-OH to PEEK was 8:2);

[0055] The fluorinated polyetheretherketone was mixed with a solvent (N-methylpyrrolidone and dichloromethane in a volume ratio of 1:8) to obtain a soluble polyetheretherketone solution with a concentration of 3 mg / mL;

[0056] After adding NH2-MWCNTs and GnPs (the mass ratio of NH2-MWCNTs and GnPs is 2:8) to the soluble polyetheretherketone solution having a concentration of 3 mg / mL (the mass ratio of the total mass of NH2-MWCNTs and GnPs to the fluorinated polyetheretherketone is 20:7.2), ultrasonic vibration (ultrasonic frequency is 20 kHz) is performed for 30 minutes to obtain a spray liquid (the total mass concentration of NH2-MWCNTs and GnPs is 5 mg / mL);

[0057] The PBO-OH / PEEK fiber cloth (size 20×20×0.05 cm, mass 0.25 g) was electrostatically sprayed using a handheld electrostatic spray gun: after spraying the spray liquid on one side of the PBO-OH / PEEK fiber cloth, the PBO-OH / PEEK fiber cloth was removed and dried in a blast drying oven at 40°C for 2 h, and then the above steps were repeated for double-sided spraying (during the spraying process, under grounding conditions, the spraying voltage was set to 60 kV, the distance between the nozzle and the PBO-OH / PEEK fiber cloth fixed on the uniformly rotating roller was 20 cm, and the rear knob of the spray gun was adjusted to control the nozzle flow rate (High mode)) to obtain a high thermal conductive composite film. The amounts of the raw materials used in Examples 1 to 7 are shown in Table 1:

[0058] Table 1 Amount of each raw material in Examples 1 to 7

[0059] Type of raw materials (g) Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 GnPs 0.0078 0.0163 0.0259 0.0367 0.049 0.063 0.0791 <![CDATA[NH2-MWCNTs]]> 0.0019 0.0041 0.0065 0.0092 0.012 0.015 0.0198 FPEEK 0.0035 0.0074 0.0117 0.0166 0.022 0.0283 0.0357

[0060] The mass percentages of NH2-MWCNTs and GnPs in the high thermal conductivity composite films obtained in Examples 1 to 7 are shown in Table 2:

[0061] Table 2 Mass percentage of NH2-MWCNTs and GnPs in the high thermal conductivity composite films obtained in Examples 1 to 7

[0062] Example Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 wt% 5 10 15 20 25 30 35

[0063] Comparative Example 1

[0064] Refer to Example 1, except that the PBO fiber is not subjected to hydroxylation modification, that is, the PBO-OH fiber is replaced by the PBO fiber.

[0065] Comparative Example 2

[0066] Refer to Example 2, except that the PBO fiber is not subjected to hydroxylation modification, that is, the PBO-OH fiber is replaced by the PBO fiber.

[0067] Comparative Example 3

[0068] Refer to Example 3, except that the PBO fiber is not subjected to hydroxylation modification, that is, the PBO-OH fiber is replaced by the PBO fiber.

[0069] Comparative Example 4

[0070] Refer to Example 4, except that the PBO fiber is not subjected to hydroxylation modification, that is, the PBO-OH fiber is replaced by the PBO fiber.

[0071] Comparative Example 5

[0072] Refer to Example 5, except that the PBO fiber is not subjected to hydroxylation modification, that is, the PBO-OH fiber is replaced by the PBO fiber.

[0073] Comparative Example 6

[0074] Refer to Example 6, except that the PBO fiber is not subjected to hydroxylation modification, that is, the PBO-OH fiber is replaced by the PBO fiber.

[0075] Comparative Example 7

[0076] Refer to Example 7, except that the PBO fiber is not subjected to hydroxylation modification, that is, the PBO-OH fiber is replaced by the PBO fiber.

[0077] Test Case

[0078] According to the standard of GB / T 10294-2008, the in-plane thermal conductivity and out-of-plane thermal conductivity of the high thermal conductive composite films described in Examples 1 to 7 and the high thermal conductive composite films described in Comparative Examples 1 to 7 were measured. The test results are shown in Table 3:

[0079] Table 3 In-plane thermal conductivity and out-of-plane thermal conductivity of the high thermal conductivity composite films of Examples 1 to 7 and Comparative Examples 1 to 7

[0080]

[0081]

[0082] Figure 2 The in-plane thermal conductivity and out-of-plane thermal conductivity of the high thermal conductivity composite films of Examples 1 to 7 (b) and Comparative Examples 1 to 7 (a) and their corresponding thermal conductivity enhancement diagrams are shown. Figure 2 As can be seen from Table 1, with the continuous increase of the filler (NH2-MWCNTs and GnPs) content, the two high thermal conductive composite films show a monotonically increasing thermal conductivity, and the change trend is basically the same. The thermal conductivity of the high thermal conductive composite films described in Examples 1 to 7 is significantly higher than that of the high thermal conductive composite films described in Comparative Examples 1 to 7. The main reason is that when the filler (NH2-MWCNTs and GnPs) is small, even if a high thermal conductive path is constructed on the surface of the PBO fiber, it still cannot help form a continuous thermal conductive path between the carbon fillers. Therefore, the formation of an effective thermal conductive path still depends on the close stacking between the carbon paper fillers. When the filler content is increased to 35%, the in-plane thermal conductivity of the high thermal conductive composite films described in Examples 1 to 7 and Comparative Examples 1 to 7 is 24.44 W·m -1 ·K -1 and 25.82W·m -1 ·K -1 , compared with pure PEEK, the thermal conductivity growth rates are 10526% and 11129% times, respectively, which indicates that PBO-OH fibers promote the enhancement of thermal conductivity;

[0083] Figure 3 The electrical conductivity of the high thermal conductivity composite film of Examples 1 to 7, wherein (a) is the electrical conductivity, (b) is the Joule heating temperature change of the high thermal conductivity composite film of Examples 1 to 7 under gradient voltage; (c) is the temperature change curve of the high thermal conductivity composite film of Examples 1 to 7 under different input voltages; (d) is the infrared thermal imaging image corresponding to the high thermal conductivity composite film of Examples 1 to 7 under different input voltages; (e) is the cyclic stability of the Joule heating performance of the high thermal conductivity composite film of Examples 1 to 7 under 10V input voltage; Figure 3 As can be seen in (a), with the increase of carbon filler content (NH2-MWCNTs and GnPs) in the high thermal conductivity composite film, the conductivity first increases slowly, and then rises sharply from 490.7 to 4973.6 S / m, which is higher than that of pure PEEK (10 -14 S / m) is 17 orders of magnitude higher; Figure 3As can be seen in (b), the change of gradient voltage (0-12V and 12-0V) causes the temperature of the high thermal conductivity composite film to change in real time, indicating that it has good fast response characteristics; the temperature-time response of the high thermal conductivity composite film includes an initial heating stage, followed by isothermal behavior after reaching a steady state, and finally natural cooling when the voltage is removed; Figure 3 As can be seen in (c), the heating and cooling processes are both stable and rapid responses, and the change trends are basically similar, which confirms that the high thermal conductivity composite film has excellent Joule heating efficiency; Figure 3 As can be seen in (d), the steady-state surface temperature of the high thermal conductivity composite film increases with increasing voltage, and its maximum steady-state temperature is 105.9°C when the applied voltage is 12V. The reliability and durability of Joule heating performance are crucial. Long-term stability tests were conducted by cycling on and off at 10V. After 8 cycles, there was no significant change in the saturation temperature and temperature change trend (e.g., Figure 3 As shown in (e), it can be seen from the above that the high thermal conductivity composite films described in Examples 1 to 7 have good Joule heating stability and reliability;

[0084] The electromagnetic interference shielding performance of the high thermal conductivity composite films described in Examples 1 to 7 in the X-band (8.2 to 12.4 GHz) was measured using a vector network analyzer and a standard waveguide method. Figure 4 is the electromagnetic shielding performance of the high thermal conductive composite film of Examples 1 to 7, wherein (a) is the total shielding effectiveness (SE) of the high thermal conductive composite film of Examples 1 to 7 at 8.2 GHz. T ), absorption loss (SE A ) and reflection loss (SE R ), (b) is the absorption coefficient (A), reflection coefficient (R) and transmission coefficient (T) of the high thermal conductive composite film described in Examples 1 to 7; (c) is the total shielding effectiveness (SE) of the high thermal conductive composite film described in Examples 1 to 7 at different frequencies T );Depend on Figure 4 As shown in (a), when the filler content is 2.5%, the EMI shielding performance of the high thermal conductivity composite film is improved to more than 20dB, reaching the commercial application standard; Figure 4 As shown in (b), as the filler content increases from 2.5% to 20.12%, R shows a gradually increasing trend, and the reflection coefficient of the high thermal conductivity composite film increases from 0.66 to 0.98. In addition, the reflection coefficient of the high thermal conductivity composite film is always higher than the absorption coefficient and the transmission coefficient, which proves that the shielding mechanism of the high thermal conductivity composite film is mainly reflective shielding; Figure 4 From (c), we can see that when the filler content is 20.12%, the best SE of the high thermal conductivity composite film is TThe value is 120.8dB, and the shielding effect reaches 99.999999999992%, indicating that the high thermal conductivity composite film can shield most electromagnetic waves. This is because as the carbon filler content in the high thermal conductivity composite film increases, the carbon filler with high conductivity is oriented along the PBO-OH / PEEK fiber cloth, which has a positive effect on the electron migration between adjacent carbon fillers, thereby improving the conductivity of the high thermal conductivity composite film. In addition, the grid structure of the high thermal conductivity composite film also provides multiple interfaces for the scattering and reflection of incident electromagnetic waves, further improving the shielding efficiency.

[0085] Based on the above test performance, it can be seen that the high thermal conductivity composite films described in Examples 1 to 7 have excellent stress-strain properties and electrical conductivity, so they can be applied to the field of sensing to monitor various daily movements of the human body. Since the carbon filler has ultra-high electrical conductivity and forms a continuous three-dimensional conductive path in the high thermal conductivity composite film, it is reasonable to infer the sensing mechanism. Due to the interaction between non-covalent bonds and hydrogen bonds, the carbon fillers attached to the high thermal conductivity composite film network are like silk inside the high thermal conductivity composite film, rather than simply stacked together; when subjected to external force, the conductive distance between the evenly dispersed carbon fillers can be significantly shortened, thereby obtaining ultra-high pressure sensitivity; the high thermal conductivity composite film is tightly attached to the joints of the fingers and connected to the application in the smartphone to monitor the resistance changes in real time, wherein, Figure 5 The graph is a graph showing the change in the relative resistance value (ΔR / R0) of the high thermal conductive composite film described in Example 7 as the extended finger slowly changes to a bent finger. Figure 5 As can be seen, the ΔR / R0 signal increases with the finger's bending angle. When the finger is bent at a certain angle, the ΔR / R0 signal reaches a peak value. Due to the elasticity of the high thermal conductivity composite film, when the finger is flattened again, the ΔR / R0 signal returns to its initial value. By sensing changes in relative resistance, the high thermal conductivity composite film enables real-time monitoring of various body movements. This highly thermally conductive composite film also has great potential for model feedback in smart wearable electronic products and medical monitoring.

[0086] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a high thermal conductivity composite film, characterized in that: The following steps are involved: The hydroxyl-modified poly (p-phenylene benzobisoxazole) fiber and poly (ether ether ketone) fiber are blended to obtain PBO-OH / PEEK fiber cloth; After mixing the soluble polyetheretherketone solution, NH2-MWCNTs and GnPs, ultrasonication was performed to obtain a spraying solution; The high thermal conductivity composite film is obtained by spraying the spraying liquid on the upper and lower surfaces of the PBO-OH / PEEK fiber cloth in an electrostatic spraying manner and then hot pressing.

2. The preparation method according to claim 1, wherein The preparation method of the hydroxyl-modified poly(p-phenylene benzobisoxazole) fiber comprises: subjecting the poly(p-phenylene benzobisoxazole) fiber to plasma treatment to obtain the hydroxyl-modified poly(p-phenylene benzobisoxazole) fiber; The plasma used in the plasma treatment is a mixed plasma of oxygen and argon with a pressure ratio of (2-4): (1-3); the input power of the plasma treatment is 100-200W, and the time is 10-20 minutes.

3. The preparation method according to claim 1, wherein The concentration of soluble polyetheretherketone in the soluble polyetheretherketone solution is 3 to 10 mg / mL, and the polyetheretherketone is fluorinated polyetheretherketone; The solvents in the soluble polyetheretherketone solution are N-methylpyrrolidone and dichloromethane; the volume ratio of the N-methylpyrrolidone to dichloromethane is (1-3): (9-7).

4. The preparation method according to claim 1, wherein The mass ratio of the NH2-MWCNTs and GnPs is (1-9): (9-1); The total concentration of NH2-MWCNTs and GnPs in the spraying liquid is 1-5 mg / mL.

5. The preparation method according to claim 1, wherein The frequency of the ultrasound is 20 to 30 KHz, and the duration is 20 to 40 minutes.

6. The preparation method according to claim 1, wherein The spraying voltage is 40-60 kV, and the distance between the nozzle and the PBO-OH / PEEK fiber cloth is 20-40 cm.

7. The preparation method according to claim 1, wherein The temperature of the hot pressing is 360-380° C., the pressure is 10-50 MPa, and the holding time is 10-20 minutes.

8. The preparation method according to claim 1, wherein The total mass percentage of NH2-MWCNTs and GnPs in the high thermal conductivity composite film is 5-35%.

9. A high thermal conductivity composite film prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the high thermal conductivity composite film according to claim 9 in the field of smart wearable electronics or medical devices.

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