A modified graphene oxide nanomaterial enhanced heat dissipation film and its preparation method

Abstract

This invention discloses a modified graphene oxide nanomaterial-enhanced heat dissipation film and its preparation method, comprising the following steps: preparing a mixed solution of graphene oxide, nano-zinc oxide, titanium dioxide, nano-ceramic microspheres, and polyethylene glycol, and sintering it to obtain a hybrid nanomaterial with a "semi-coated" structure; preparing a precursor spinning solution using the hybrid nanomaterial, amide solvent, and polyvinylidene fluoride, and preparing a hybrid fiber membrane using electrospinning; and obtaining a flexible heat dissipation film material through cold pressing and hot pressing. The film prepared by this invention has a solar absorptivity of 0.03-0.06, a hemispherical emissivity of 0.88-0.91, a tensile strength of 101-112 MPa, a total mass loss (TML) of <1%, a condensable volatile matter (CVCM) of <0.1%, and stable optical performance after 100 high and low temperature thermal cycling tests at -100 to +100℃, exhibiting excellent adaptability to the space environment and basically meeting the high-power heat dissipation requirements of spacecraft.

Description

Technical Field

[0001] This invention relates to the field of thermal control materials technology, specifically to a modified graphene oxide nanomaterial-enhanced heat dissipation film and its preparation method. Background Technology

[0002] Spacecraft thermal control materials regulate the surface thermal equilibrium temperature of a spacecraft through their own thermophysical properties, namely solar absorptivity and hemispherical emissivity, thereby achieving the purpose of effective thermal control of the spacecraft.

[0003] As spacecraft functions and performance requirements continue to increase, their power output has risen dramatically, leading to a sharp increase in heat. If this heat is not dissipated in time, the spacecraft will remain in an overheated state for extended periods, making it highly susceptible to malfunctions or failures. On-orbit flight data shows that over half of the failures of electronic equipment are caused by inadequate thermal management. Therefore, efficient thermal management has become one of the most severe bottlenecks restricting spacecraft development.

[0004] Currently, the performance of conventional thermal control films and coatings is limited by their inherent physical properties, making further improvements difficult. Aerospace development demands efficient heat dissipation, flexibility, and lightweight design for thermal control systems. Spacecraft heat dissipation currently relies on fixed heat dissipation surfaces such as optical solar reflectors, which are inefficient, heavy, and difficult to adapt to complex surface mounting, thus failing to meet high-power heat dissipation requirements. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a modified graphene oxide nanomaterial-enhanced heat dissipation film and its preparation method. This flexible heat dissipation film has the characteristics of flexibility and lightweight, low absorption and high emission, as well as good mechanical properties, thus solving the shortcomings of existing similar products, such as large weight, poor mechanical properties, and difficulty in adapting to the complex surfaces of spacecraft.

[0006] The objective of this invention can be achieved through the following methods:

[0007] This invention provides a modified graphene oxide nanomaterial-enhanced heat dissipation film. The modified graphene oxide nanomaterial-enhanced heat dissipation film is prepared by configuring hybrid nanomaterials, an amide solvent, and polyvinylidene fluoride into a precursor spinning solution, followed by electrospinning to obtain a hybrid fiber membrane; then, a flexible film composite material is obtained through cold pressing and hot pressing processes. The hybrid nanomaterial is prepared by freezing and sintering a mixed solution of graphene oxide and nano-oxides. Specifically, using polyethylene glycol as a solvent, graphene oxide is added, the pH is adjusted to alkaline, nano-oxides are added, and the mixture is frozen and sintered to obtain a "semi-encapsulated" hybrid nanomaterial.

[0008] This invention provides a method for preparing a modified graphene oxide nanomaterial enhanced heat dissipation film, the preparation method comprising the following steps:

[0009] S1. Prepare a graphene oxide solution, adjust the pH value, disperse it ultrasonically, add nano-oxide, and degas to obtain a mixed slurry;

[0010] S2. Freeze the mixed slurry to form a solidified shape, freeze-dry it after solidification, and then sinter it to obtain a hybrid nanomaterial with a "semi-encapsulated" structure.

[0011] S3. Disperse the obtained hybrid nanomaterials in an amide solvent to form a suspension, add polyvinylidene fluoride and stir to dissolve, forming a precursor spinning solution;

[0012] S4. Electrospinning the precursor spinning solution to obtain a hybrid fiber membrane, followed by cold pressing and hot pressing to obtain the modified graphene oxide nanomaterial-enhanced heat dissipation film.

[0013] In one embodiment of the present invention, in step S1, the graphene oxide content in the graphene oxide solution is 0.1-5 wt%, and the solvent is polyethylene glycol.

[0014] In one embodiment of the present invention, in step S1, the pH value is 8-10, which is adjusted by adding ammonia.

[0015] In one embodiment of the present invention, the ultrasonic dispersion time in step S1 is 2-4 h.

[0016] In one embodiment of the present invention, in step S1, the nano-oxide is a mixture of nano-zinc oxide, nano-titanium dioxide, and nano-ceramic microspheres, with a mixture density of 0.2-1 g / cm³. 3 The mass ratio is 0.5-3.5:4.5-7.5:5-9. The dosage ratio of nano-oxide to graphene oxide solution is 10-20g:100ml. Mixing the three nano-oxides can improve the solar absorptivity, hemispherical emissivity, and resistance to space environment radiation in the final product. Within this density range, product performance can be further enhanced.

[0017] As one embodiment of the present invention, in step S1, the degassing process specifically involves: adding an antifoaming agent, including n-butanol, to defoam; then transferring the product to a vacuum oven for degassing until no obvious bubbles escape.

[0018] As one embodiment of the present invention, in step S2, freeze molding involves pouring the slurry into a mold and placing it on a cold source (3-5 ℃) for freeze molding; drying involves demolding the slurry after it has completely solidified and transferring it to a vacuum freeze dryer for freeze drying.

[0019] In one embodiment of the present invention, the sintering process in step S2 is as follows: the temperature is increased to 200-300℃ at a heating rate of 3-10℃ / min, then increased to 580-620℃ at a heating rate of 2-5℃ / min, and held for 0.5-2 hours; then increased to 680-720℃ at a heating rate of 2-5℃ / min, and held for 0.5-2 hours. Calcination yields a hybrid nanomaterial with a "semi-coated" structure of graphene-coated nano-oxides. Segmented heating ensures product performance and prevents product delamination and defects. Graphene coating further enhances product performance, with semi-coated coating exhibiting even better performance.

[0020] In one embodiment of the present invention, in step S3, the mass content of hybrid nanomaterials in the precursor spinning solution is 3%-10%; the dispersion is performed by ultrasonication for 5-10 minutes to prepare a uniform suspension.

[0021] In one embodiment of the present invention, in step S3, polyvinylidene fluoride is added and dissolved by stirring at 80°C to form a precursor spinning solution. The polyvinylidene fluoride content in the precursor spinning solution is 10%-50% by mass.

[0022] In one embodiment of the present invention, step S4, electrospinning specifically involves: placing the precursor spinning solution in a syringe, fixing the syringe to an injection pump, fixing the positive conductive clamp to the needle tip, and grounding the roller electrode to perform spinning to obtain a hybrid fiber membrane. The electrospinning parameters are: injection pump feed rate of 1-20 ml / h, voltage of 2-25 kV, roller-needle distance of 5-30 cm, receiving roller rotation speed of 500-2000 r / min, spinning humidity of 10-40%, and temperature of 10-30℃. After spinning, the membrane is vacuum dried at 20-60℃ for 6-12 hours.

[0023] As one embodiment of the present invention, in step S4, the pressure of the cold pressing treatment is 10-40 MPa and the time is 1-20 min. Cold pressing is performed at room temperature, under which the gap between nanofibers can be greatly compressed.

[0024] In one embodiment of the present invention, in step S4, the pressure of the hot pressing treatment is 1-10 MPa, the temperature is 70-200℃, and the time is 2-4 h.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The flexible heat dissipation film of the present invention has good thermal control performance (solar absorptivity, hemispherical emissivity), good adaptability to space environment, strong feasibility, and stable performance after 100 temperature shock tests from -100 to +100℃, and has low vacuum outgassing.

[0027] (2) The flexible heat dissipation film provided by the present invention has the following characteristics:

[0028] a) Appearance: The film surface is uniform, free of bubbles and cracks;

[0029] b) Solar absorptivity 0.03-0.06;

[0030] c) Hemispherical emissivity 0.88-0.91;

[0031] d) Tensile strength 101-112 MPa;

[0032] e) Vacuum gas evolution performance: meets the requirements of TML < 1% and CVCM < 0.1%;

[0033] f) Thermal cycling test: After 100 cycles of high and low temperature thermal cycling test from -100 to +100℃, there is no cracking, blistering or discoloration, and the optical performance is stable.

[0034] g) After 15 years of equivalent dose space environment irradiation in a sun-synchronous orbit, the reflectivity of the flexible heat dissipation film changes by no more than 8%. Attached Figure Description

[0035] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0036] Figure 1 This is the preparation process of flexible heat dissipation films. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the various embodiments of this invention will be described in detail below. However, those skilled in the art will understand that many technical details have been provided in the various embodiments of this invention to facilitate a better understanding of this application. However, the technical solutions claimed in the claims of this application can be implemented even without these technical details and with various variations and modifications based on the following embodiments.

[0038] Example 1

[0039] This embodiment provides a method for preparing a modified graphene oxide nanomaterial-enhanced heat dissipation film, including the preparation steps and testing methods as follows: Figure 1 As shown, the details are as follows:

[0040] Prepare 100 ml of a polyethylene glycol solution containing 0.5 wt% graphene oxide, and adjust the pH to 8 by adding ammonia. After ultrasonic dispersion for 2 hours, add a 1 g / cm³ solution. 3A mixture of 3g nano-zinc oxide, 5g nano-titanium dioxide, and 7g nano-ceramic microspheres, totaling 15g, was mechanically stirred. 8ml of n-butanol (an antifoaming agent) was added, and the mixture was transferred to a vacuum oven for degassing until no obvious bubbles escaped. The slurry was poured into a mold and placed on a cold source at 5℃ for freeze-drying for 15 minutes. After complete solidification, the slurry was demolded and transferred to a vacuum freeze dryer for freeze-drying for 30 minutes. After drying, the green body was sintered in a tube furnace using the following sintering process: 25-250℃, heating rate 5℃ / min; 250-600℃, heating rate 5℃ / min, holding at 600℃ for 2 hours; 600-700℃, heating rate 5℃ / min, holding for 2 hours, resulting in a hybrid nanomaterial with a "semi-encapsulated" structure.

[0041] The hybrid nanomaterials were placed in 55 ml of formamide solution and ultrasonically dispersed for 10 min to prepare a homogeneous suspension. 45 g of polyvinylidene fluoride was added to the suspension and stirred at 80 °C to dissolve, forming a precursor spinning solution containing 10% hybrid nanomaterials.

[0042] The precursor spinning solution was placed in a syringe. The syringe was fixed to an injection pump, and the positive conductive clamp was fixed to the needle tip. The roller electrode was grounded. The injection pump feed rate was 10 ml / h, the voltage was 20 kV, and the distance between the roller and the needle tip was 150 cm. The receiving roller rotation speed was 1000 r / min. The spinning humidity was 30%, and the temperature was 20℃. After spinning, the mixture was vacuum dried at 60℃ for 8 h to obtain a hybrid fiber membrane.

[0043] The hybrid fiber membrane was cold-pressed at 30 MPa and room temperature for 10 min, under which the gaps between the nanofibers could be greatly compressed. The cold-pressed film was then stretched and hot-pressed at 10 MPa and 200℃ for 2 h. The resulting flexible film composite material was obtained.

[0044] Example 2

[0045] This embodiment provides a method for preparing a modified graphene oxide nanomaterial-enhanced heat dissipation film, as detailed below:

[0046] A polyethylene glycol solution containing 3 wt% graphene oxide was prepared, and ammonia was added to adjust the pH to 10. After ultrasonic dispersion for 2 hours, a 0.5 g / cm³ density solution was added. 3A mixture of 1.5g of nano-zinc oxide, 5.5g of nano-titanium dioxide, and 8g of nano-ceramic microspheres, totaling 15g, was mechanically stirred. 8ml of n-butanol (an antifoaming agent) was added, and the mixture was transferred to a vacuum oven for degassing until no obvious bubbles escaped. The slurry was poured into a mold and placed on a cold source at 5℃ for freeze-drying for 15 minutes. After complete solidification, the slurry was demolded and transferred to a vacuum freeze dryer for freeze-drying for 30 minutes. After drying, the green body was sintered in a tube furnace using the following sintering process: 25-250℃, heating rate 3℃ / min; 250-600℃, heating rate 3℃ / min, holding at 600℃ for 2 hours; 600-700℃, heating rate 3℃ / min, holding for 2 hours. This yielded a hybrid nanomaterial with a "semi-encapsulated" structure.

[0047] The hybrid nanomaterials were placed in 55 ml of formamide solution and ultrasonically dispersed for 10 min to prepare a homogeneous suspension. 45 g of polyvinylidene fluoride was added to the suspension and stirred at 80 °C to dissolve, forming a precursor spinning solution containing 6% hybrid nanomaterials.

[0048] The precursor spinning solution was placed in a syringe. The syringe was fixed to an injection pump, and the positive conductive clamp was fixed to the needle tip. The roller electrode was grounded. The injection pump feed rate was 15 ml / h, the voltage was 15 kV, and the distance between the roller and the needle tip was 10 cm. The receiving roller rotation speed was 2000 r / min. The spinning humidity was 25%, and the temperature was 25℃. After spinning, the mixture was vacuum dried at 40℃ for 6 h to obtain a hybrid fiber membrane.

[0049] The hybrid fiber membrane was cold-pressed at 20 MPa and room temperature for 15 min, under which the gaps between the nanofibers could be greatly compressed. The cold-pressed film was then stretched and hot-pressed at 8 MPa and 120℃ for 3 h. The resulting flexible film composite material was obtained.

[0050] Example 3

[0051] A polyethylene glycol solution with a graphene oxide content of 5 wt% was prepared, and the pH was adjusted to 10 by adding ammonia. After ultrasonic dispersion for 3 hours, a 0.3 g / cm³ density polyethylene glycol solution was added. 3A mixture of 0.6g nano-zinc oxide, 7g nano-titanium dioxide, and 7.4g nano-ceramic microspheres, totaling 15g, was mechanically stirred. 8ml of n-butanol (an antifoaming agent) was added, and the mixture was transferred to a vacuum oven for degassing until no obvious bubbles escaped. The slurry was poured into a mold and placed on a cold source at 5℃ for freeze-drying for 15 minutes. After complete solidification, the mold was removed and transferred to a vacuum freeze dryer for freeze-drying for 30 minutes. After drying, the green body was sintered in a tube furnace using the following sintering process: 25-250℃, heating rate 10℃ / min; 250-600℃, heating rate 5℃ / min, holding at 600℃ for 1 hour; 600-700℃, heating rate 5℃ / min, holding for 1 hour. This yielded a hybrid nanomaterial with a "semi-encapsulated" structure.

[0052] The hybrid nanomaterials were placed in 55 ml of formamide solution and ultrasonically dispersed for 5 min to prepare a homogeneous suspension. 45 g of polyvinylidene fluoride was added to the suspension and stirred at 80 °C to dissolve, forming a precursor spinning solution containing 3% hybrid nanomaterials.

[0053] The precursor spinning solution was placed in a syringe. The syringe was fixed to an injection pump, and the positive conductive clamp was fixed to the needle tip. The roller electrode was grounded. The injection pump feed rate was 5 ml / h, the voltage was 8 kV, and the distance between the roller and the needle tip was 20 cm. The receiving roller rotation speed was 800 r / min. The spinning humidity was 20%, and the temperature was 15℃. After spinning, the mixture was vacuum dried at 35℃ for 8 h to obtain a hybrid fiber membrane.

[0054] The hybrid fiber membrane was cold-pressed at 15 MPa and room temperature for 20 min, under which the gaps between the nanofibers could be greatly compressed. The cold-pressed film was then stretched and hot-pressed at 5 MPa and 80℃ for 4 h. The resulting flexible film composite material was obtained.

[0055] Comparative Example 1

[0056] This comparative example provides a method for preparing a modified graphene oxide nanomaterial enhanced heat dissipation film, which is basically the same as Example 1, except that: the same amount of graphene and a mixture of nano zinc oxide, nano titanium dioxide and nano ceramic microspheres are directly placed in 55 ml of formamide solution to prepare a suspension.

[0057] The resulting thin film exhibited poor thermal control performance, with a solar absorptivity of 0.12 and a hemispherical emissivity of 0.83.

[0058] Comparative Example 2

[0059] This comparative example provides a method for preparing a modified graphene oxide nanomaterial-enhanced heat dissipation film, which is basically the same as Example 1, except that the mixture of nano zinc oxide, nano titanium dioxide, and nano ceramic microspheres is replaced with an equal amount of nano zinc oxide.

[0060] The resulting thin film exhibited poor thermal control performance, with a solar absorptivity of 0.10 and a hemispherical emissivity of 0.84.

[0061] Comparative Example 3

[0062] This comparative example provides a method for preparing a modified graphene oxide nanomaterial enhanced heat dissipation film, which is basically the same as Example 1, except that the mixture of nano zinc oxide, nano titanium dioxide, and nano ceramic microspheres is replaced with an equal amount of nano ceramic microspheres.

[0063] The adaptability of the thin film to the space environment needs to be improved. After 15 years of equivalent dose space environment irradiation in a sun-synchronous orbit, the reflectivity of the flexible heat dissipation film changed by more than 25%.

[0064] Comparative Example 4

[0065] This comparative example provides a method for preparing a modified graphene oxide nanomaterial-enhanced heat dissipation film, which is basically the same as that in Example 1, except that the sintering process is 25-700℃, the heating rate is 5℃ / min, and the holding time is 4h.

[0066] The resulting film has poor mechanical properties, numerous internal defects, and is prone to delamination. Its tensile strength is 75 MPa.

[0067] Performance testing:

[0068] The films of the above embodiments and comparative examples were subjected to performance tests, and the test methods are as follows:

[0069] (1) Solar absorptivity test

[0070] This experiment used a LAMBDA960 UV / VIS / NIR spectrophotometer to measure the solar absorptivity, with a measurable wavelength range of 200 nm to 2500 nm.

[0071] (2) Hemispherical emissivity test

[0072] The hemispherical emissivity of the sample in the 3–35 μm band at room temperature was measured using a TEMP 2000A emissivity meter. Its measurement accuracy was ±3% and its full-band repeatability was ±0.5%.

[0073] (3) Mechanical property testing

[0074] Tensile properties were tested using an electronic universal testing machine. The maximum load of the electronic universal testing machine is 200KN, the load accuracy is ±0.01%, the displacement resolution is 0.04µm, and the measurement accuracy is ±0.5%.

[0075] Table 1 Solar absorptivity and emissivity

[0076]

[0077] (4) Thermal cycling test

[0078] A temperature shock chamber was used, and in accordance with the requirements of GJB 2704A-2006 standard, 100 thermal cycles were performed at temperatures ranging from -100℃ to +100℃ under normal atmospheric conditions. The test conditions are as follows:

[0079] 1. Test temperature: The high-end temperature is 100℃, and the low-end temperature is set at -100℃;

[0080] Second, number of cycles: 100;

[0081] Third, temperature control error: high temperature ±5℃, low temperature ±10℃;

[0082] Fourth, the thermal cycling device should have two constant temperature zones with different temperatures, and the sample should be transferred from one constant temperature zone to the other within 10 seconds.

[0083] Fifth, keep the sample at the high and low temperature ends for 5 minutes to ensure that the temperature of the sample is the same as the ambient temperature;

[0084] Sixth, dehumidification measures should be taken during the test to prevent frost from forming on the surface of the test piece;

[0085] Test results: After 100 high and low temperature thermal cycles at -100 to +100℃, the appearance remained intact and the optical performance was stable.

[0086] (5) Vacuum outgassing performance test

[0087] The vacuum venting test was conducted according to standard GJB 2704A-2006, and the test conditions are as follows:

[0088] First, the sample is heated to a temperature of 125°C ± 1°C or 150°C ± 1°C.

[0089] Second, the collection temperature for condensable volatiles is 25°C.

[0090] Third, test pressure: better than 7×10 -3 Pa;

[0091] 4. Insulation time: 24 hours;

[0092] 5. Sample pretreatment: 23°C±1°C, humidity 45%RH±10%RH, for 24 hours;

[0093] 6. Balance test sensitivity: 1μg.

[0094] The total mass loss (TML) and condensable volatile matter (CVCM) of the material in vacuum were tested and calculated, as shown in Table 2.

[0095] Table 2 Vacuum venting performance

[0096]

[0097] Based on Tables 1 and 2 and the experimental results, the properties of the thin film of the present invention are as follows:

[0098] 1. Appearance: No bubbles, no cracks;

[0099] Second, solar absorptivity: 0.22–0.27;

[0100] Third, hemispherical emissivity: 0.85~0.91;

[0101] 4. Tensile strength: 101-112 mga;

[0102] 5. Thermal cycling test: After 100 cycles of high and low temperature thermal cycling at -100 to +100℃, there is no cracking, blistering, or discoloration, and the optical performance remains stable;

[0103] 6. Vacuum venting performance: all meet the requirements of TML<1% and CVCM<0.1%;

[0104] 7. After 15 years of equivalent dose space environment irradiation in a sun-synchronous orbit, the reflectivity of the flexible heat dissipation film changes by no more than 8%.

[0105] In summary, the flexible heat dissipation film prepared by this invention has a solar absorptivity of 0.03-0.06, a hemispherical emissivity of 0.88-0.91, a tensile strength of 101-112 MPa, a total mass loss (TML) of <1%, a condensable volatile matter (CVCM) of <0.1%, and stable optical performance after 100 high and low temperature thermal cycling tests at -100 to +100℃, demonstrating excellent adaptability to space environments.

[0106] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A modified graphene oxide nanomaterial-enhanced heat dissipation film, characterized in that, The modified graphene oxide nanomaterial-enhanced heat dissipation film is prepared by electrospinning a precursor spinning solution composed of hybrid nanomaterials, amide solvent, and polyvinylidene fluoride to obtain a hybrid fiber film; then, it is obtained through cold pressing and hot pressing processes; the hybrid nanomaterial is prepared by freeze-forming and then sintering in segments from a mixed solution of graphene oxide and nano-oxide. The nano-oxide is a mixture of nano-zinc oxide, nano-titanium dioxide, and nano-ceramic microspheres, with a density of 0.2-1 g / cm³. 3 The mass ratio is 0.5-3.5:4.5-7.5:5-9.

2. A method for preparing a modified graphene oxide nanomaterial enhanced heat dissipation film as described in claim 1, characterized in that, The preparation method includes the following steps: S1. Prepare a graphene oxide solution, adjust the pH value, disperse it ultrasonically, add nano-oxide, and degas to obtain a mixed slurry; S2. Freeze the mixed slurry to form a solidified shape, freeze-dry it after solidification, and then sinter it to obtain a hybrid nanomaterial with a "semi-encapsulated" structure. S3. Disperse the obtained hybrid nanomaterials in an amide solvent to form a suspension, add polyvinylidene fluoride and stir to dissolve, forming a precursor spinning solution; S4. Electrospinning the precursor spinning solution to obtain a hybrid fiber membrane, followed by cold pressing and hot pressing to obtain the modified graphene oxide nanomaterial enhanced heat dissipation film. In step S2, the sintering process is as follows: the temperature is increased to 200-300 ℃ at a heating rate of 3-10 ℃ / min, then increased to 580-620 ℃ at a heating rate of 2-5 ℃ / min, and held for 0.5-2 h; then increased to 680-720 ℃ at a heating rate of 2-5 ℃ / min, and held for 0.5-2 h.

3. The preparation method according to claim 2, characterized in that, In step S1, the graphene oxide content in the graphene oxide solution is 0.1-5 wt%.

4. The preparation method according to claim 2, characterized in that, In step S1, the pH value is 8-10.

5. The preparation method according to claim 2, characterized in that, In step S3, the mass content of hybrid nanomaterials in the precursor spinning solution is 3%-10%.

6. The preparation method according to claim 2, characterized in that, In step S3, the precursor spinning solution contains 10%-50% polyvinylidene fluoride by mass.

7. The preparation method according to claim 2, characterized in that, In step S4, electrospinning specifically involves placing the precursor spinning solution in a syringe, fixing the syringe to an injection pump, fixing the positive conductive clamp to the needle, and grounding the roller electrode to perform spinning to obtain a hybrid fiber membrane. The electrospinning parameters are as follows: injection pump feed rate of 1-20 ml / h, voltage of 2-25 kV, roller-needle distance of 5-30 cm, receiving roller rotation speed of 500-2000 r / min, spinning humidity of 10-40%, and temperature of 10-30℃.

8. The preparation method according to claim 2, characterized in that, In step S4, the pressure of cold pressing is 10-40 MPa and the time is 1-20 min; the pressure of hot pressing is 1-10 MPa, the temperature is 70-200℃, and the time is 2-4 h.

Images