Polyvinylidene fluoride film based on cross-linking reaction, preparation method and application

Abstract

The invention belongs to the field of polymer films, and discloses a polyvinylidene fluoride film based on cross-linking reaction and a preparation method and application thereof, and the preparation method comprises the following steps: mixing cyclohexanone, polyvinylidene fluoride and polyoxyethylene diamine to obtain a mixed solution; curing the mixed solution into a film to obtain a blended polyvinylidene fluoride film; and carrying out cross-linking reaction on the blended polyvinylidene fluoride film to obtain a cross-linked polyvinylidene fluoride film, and culturing the cross-linked polyvinylidene fluoride film at 150-165 DEG C to obtain the polyvinylidene fluoride film with high gamma crystal form content. Through detection and comparison, in the polyvinylidene fluoride film based on the cross-linking reaction, the gamma-phase crystal content is obviously increased, and the alpha-phase crystal content is obviously reduced. The method is simple in process and convenient to operate, polyvinylidene fluoride is endowed with the capacity of obtaining gamma crystals at a low temperature in a short time, and the method can be widely applied to the fields of pressure sensors, lithium ion batteries, automobile motors, high-temperature-resistant thermistor devices and the like.

Description

Technical Field

[0001] The present invention belongs to the field of polymer films, and relates to a polyvinylidene fluoride film based on cross-linking reaction, a preparation method and an application thereof. Background Art

[0002] As a unique polymer material, polyvinylidene fluoride (PVDF) has always attracted much attention due to its excellent dielectric and ferroelectric properties. It not only has a relatively high dielectric constant and a low dielectric loss, making it have broad application potential in fields such as capacitors and dielectric materials, but also exhibits significant ferroelectricity, and can show unique hysteresis loop characteristics under the action of an electric field. In addition, PVDF also has good chemical stability and mechanical strength, and is easy to be processed into various shapes. These excellent properties make PVDF show broad application prospects in multiple fields such as electronics, energy, and intelligent materials.

[0003] Polyvinylidene fluoride is a polymorphic semi-crystalline polymer, and its most common crystal forms are three types, namely α crystal form, β crystal form and γ crystal form. Among them, the α crystal form of polyvinylidene fluoride has excellent mechanical properties and can be used in electronics, chemical industry, solar devices, etc. The β crystal form and γ crystal form of polyvinylidene fluoride have good piezoelectric and ferroelectric effects and are widely used in transducer devices in various fields, such as pressure-sensitive devices and humidity-sensitive devices, and can be applied in storage devices and intelligent electrical appliances, etc.

[0004] At present, preparing polyvinylidene fluoride with a high content of γ crystal form does face many challenges. The main reason is that the preparation steps are relatively complex and multiple process parameters need to be precisely controlled to ensure the stable transformation of crystal forms. At the same time, this process often requires a relatively high cultivation temperature, which not only increases energy consumption but also places higher requirements on equipment. More intractably, even under optimized conditions, it takes a long time to prepare polyvinylidene fluoride with a high γ crystal form content, which greatly limits the efficiency of its large-scale production and application. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned disadvantages of the prior art and provide a polyvinylidene fluoride film based on cross-linking reaction, a preparation method and an application thereof.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] In the first aspect of the present invention, a preparation method of a polyvinylidene fluoride film based on cross-linking reaction is provided, including: mixing cyclohexanone, polyvinylidene fluoride and polyethylene oxide diamine to obtain a mixed solution; solidifying the mixed solution into a film to obtain a blend polyvinylidene fluoride film; performing a cross-linking reaction on the blend polyvinylidene fluoride film to obtain a cross-linked polyvinylidene fluoride film and culturing it at 150-165 °C to obtain a polyvinylidene fluoride film with a high γ crystal form content.

[0008] Optionally, the step of mixing cyclohexanone, polyvinylidene fluoride and polyethylene oxide diamine to obtain a mixed solution includes: adding polyvinylidene fluoride to cyclohexanone to obtain a polyvinylidene fluoride solution; adding polyethylene oxide diamine to the polyvinylidene fluoride solution to obtain a mixed solution.

[0009] Optionally, in the polyvinylidene fluoride solution, the mass concentration of polyvinylidene fluoride is 3% - 10%.

[0010] Optionally, in the mixed solution, the mass fraction of polyethylene oxide diamine is 5% - 15% of that of polyvinylidene fluoride.

[0011] Optionally, the step of adding polyethylene oxide diamine to the polyvinylidene fluoride solution to obtain a mixed solution includes: adding polyethylene oxide diamine to the polyvinylidene fluoride solution at 40 - 50 °C and stirring evenly at 1000 - 5000 r / min to obtain a mixed solution.

[0012] Optionally, the step of curing the mixed solution into a film includes: dropping the mixed solution onto a glass slide and curing it into a film in a vacuum oven at 90 - 120 °C.

[0013] Optionally, the step of cross - linking the blended polyvinylidene fluoride film includes: subjecting the blended polyvinylidene fluoride film to a cross - linking reaction at 180 - 300 °C.

[0014] Optionally, the step of obtaining a cross - linked polyvinylidene fluoride film and culturing it at 150 - 165 °C includes: obtaining a cross - linked polyvinylidene fluoride film and culturing it at 150 - 165 °C for 4 - 18 h.

[0015] In the second aspect of the present invention, there is provided a polyvinylidene fluoride film based on a cross - linking reaction, which is prepared by the above - mentioned preparation method of a polyvinylidene fluoride film based on a cross - linking reaction.

[0016] In the third aspect of the present invention, there is provided an application of the above - mentioned polyvinylidene fluoride film based on a cross - linking reaction in the preparation of a thermistor device.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The preparation method of a polyvinylidene fluoride film based on a crosslinking reaction first uses cyclohexanone as a solvent to prepare a mixed system solution with polyvinylidene fluoride and polyethylene oxide diamine as solutes. Then, the solvent of the mixed system is volatilized, followed by further crosslinking reaction and cultivation at 150 - 165 °C to obtain a polyvinylidene fluoride film with a high γ-crystalline form content. Through detection and comparison, it is found that in the polyvinylidene fluoride film with the addition of polyethylene oxide diamine, the γ-phase crystal content increases significantly, and the α-phase crystal content decreases significantly. By preparing a polyvinylidene fluoride film with a high γ-crystalline form content based on a crosslinking reaction, the cultivation temperature is low, which can replace traditional processes such as filler addition and high-temperature long-time cultivation. The preparation method has a simple process and convenient operation, and can quickly obtain a high content of γ-phase crystals. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the Fourier infrared spectrogram of polyvinylidene fluoride with different crosslinking degrees in the embodiment of the present invention.

[0020] Figure 2 It is the Fourier infrared spectrogram of a polyvinylidene fluoride dielectric composite film with different cultivation times at 155 °C in the embodiment of the present invention.

[0021] Figure 3 It is the γ-crystalline polarization diagram of a polyvinylidene fluoride film crosslinked by cultivation at 155 °C for 4 hours in the embodiment of the present invention.

[0022] Figure 4 It is the γ-crystalline polarization diagram of a polyvinylidene fluoride film crosslinked by cultivation at 155 °C for 4 hours with a mass ratio of polyethylene oxide diamine to polyvinylidene fluoride of 10 wt% in the embodiment of the present invention.

[0023] Figure 5 It is the diagram of the γ-crystalline content (calculated from Fourier infrared spectroscopy data) of a polyvinylidene fluoride film crosslinked by cultivation at 155 °C for 4 hours in the embodiment of the present invention.

[0024] Figure 6 It is the X-ray diffraction spectrogram of polyvinylidene fluoride with different crosslinking degrees in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0027] The present invention will be further described in detail below with reference to the accompanying drawings:

[0028] In an embodiment of the present invention, a method for preparing a polyvinylidene fluoride film based on a crosslinking reaction is provided, specifically a method for preparing a polyvinylidene fluoride film with a high γ-crystalline form content based on the crosslinking of polyethylene oxide diamine and polyvinylidene fluoride, which has the characteristics of low cultivation temperature, short time and easy industrialization.

[0029] Specifically, the method for preparing a polyvinylidene fluoride film based on a crosslinking reaction of the present invention includes the following steps:

[0030] S1: Mix cyclohexanone, polyvinylidene fluoride and polyethylene oxide diamine to obtain a mixed solution.

[0031] S2: Solidify the mixed solution into a film to obtain a blend polyvinylidene fluoride film.

[0032] S3: Carry out a crosslinking reaction on the blend polyvinylidene fluoride film, obtain a crosslinked polyvinylidene fluoride film and cultivate it at 150 - 165 °C to obtain a polyvinylidene fluoride film with a high γ-crystalline form content.

[0033] The method for preparing a polyvinylidene fluoride film based on a crosslinking reaction of the present invention first uses cyclohexanone as a solvent to prepare a mixed system solution with polyvinylidene fluoride and polyethylene oxide diamine as solutes, then volatilizes the mixed system solvent, further carries out a crosslinking reaction and cultivates it at 150 - 165 °C to obtain a polyvinylidene fluoride film with a high γ-crystalline form content. Through detection and comparison, it is found that in the polyvinylidene fluoride film added with polyethylene oxide diamine, the γ-phase crystal content increases significantly and the α-phase crystal content decreases significantly. The present invention prepares a polyvinylidene fluoride film with a high γ-crystalline form content based on a crosslinking reaction, with a low cultivation temperature, which can replace traditional processes such as filler addition and high-temperature long-time cultivation. The preparation method has a simple process and convenient operation, and can quickly obtain a high content of γ-phase crystals.

[0034] In a possible implementation, the step of mixing cyclohexanone, polyvinylidene fluoride and polyoxyethylene diamine to obtain a mixed solution includes: adding polyvinylidene fluoride to cyclohexanone to obtain a polyvinylidene fluoride solution; adding polyoxyethylene diamine to the polyvinylidene fluoride solution to obtain a mixed solution.

[0035] In a possible implementation, in the polyvinylidene fluoride solution, the mass concentration of polyvinylidene fluoride is 3% to 10%.

[0036] Explanatorily, the mass fraction ratio of polyvinylidene fluoride to cyclohexanone determines the uniformity of the film. As the proportion of polyvinylidene fluoride gradually increases, the uniformity of the film will gradually decrease.

[0037] In a possible implementation, in the mixed solution, the mass fraction of polyoxyethylene diamine is 5% to 15% of that of polyvinylidene fluoride.

[0038] In a possible implementation, the step of adding polyoxyethylene diamine to the polyvinylidene fluoride solution to obtain a mixed solution includes: adding polyoxyethylene diamine to the polyvinylidene fluoride solution at 40 - 50 °C and stirring evenly at 1000 - 5000 r / min to obtain a mixed solution.

[0039] Exemplarily, the stirring can be carried out by magnetic stirring.

[0040] In a possible implementation, the step of curing the mixed solution into a film includes: dropping the mixed solution on a glass slide and curing it into a film in a vacuum oven at 90 - 120 °C.

[0041] In a possible implementation, the step of cross - linking the blended polyvinylidene fluoride film includes: carrying out a cross - linking reaction on the blended polyvinylidene fluoride film at 180 - 300 °C.

[0042] In a possible implementation, the step of obtaining a cross - linked polyvinylidene fluoride film and culturing it at 150 - 165 °C includes: obtaining a cross - linked polyvinylidene fluoride film and culturing it at 150 - 165 °C for 4 - 18 h.

[0043] In another embodiment of the present invention, a polyvinylidene fluoride film based on a cross - linking reaction is provided, and the polyvinylidene fluoride film based on the cross - linking reaction is prepared by the above - mentioned preparation method of the polyvinylidene fluoride film based on the cross - linking reaction.

[0044] Specifically, the polyvinylidene fluoride film based on cross-linking reaction has a high γ-crystalline form content. The presence of the high γ-crystalline form significantly improves the piezoelectric and pyroelectric properties of the polyvinylidene fluoride film, enabling it to exhibit more excellent response characteristics and sensitivity in electronic devices such as sensors and actuators. Secondly, the polyvinylidene fluoride film with a high γ-crystalline form content has better thermal stability and mechanical strength, can maintain stable performance under high temperature and harsh environments, and extends the service life. In addition, this polyvinylidene fluoride film with a high γ-crystalline form content also has good chemical stability, can resist the erosion of various chemical substances, and broadens its application fields.

[0045] The following uses specific examples to illustrate the preparation method of the polyvinylidene fluoride film based on cross-linking reaction of the present invention.

[0046] Example 1

[0047] Step 1: Using cyclohexanone as a solvent, prepare a polyvinylidene fluoride solution with a mass concentration of 3%. Then, polyethylene oxide diamine is added to the polyvinylidene fluoride solution at 45 °C and magnetically stirred evenly at 4000 r / min to obtain a mixed solution. Among them, the mass fraction of polyethylene oxide diamine is 5% of that of polyvinylidene fluoride.

[0048] Step 2: Drop the mixed solution in Step 1 onto a glass slide and cure it into a film in a vacuum oven at 90 °C to obtain a blended polyvinylidene fluoride film.

[0049] Step 3: Place the blended polyvinylidene fluoride film obtained in Step 2 in an oven at 180 °C for cross-linking reaction to obtain a cross-linked polyvinylidene fluoride film.

[0050] Step 4: Cultivate the cross-linked polyvinylidene fluoride film obtained in Step 3 at 150 °C for 18 hours to obtain a polyvinylidene fluoride film with a high γ-crystalline form content.

[0051] Example 2

[0052] Step 1: Using cyclohexanone as a solvent, prepare a polyvinylidene fluoride solution with a mass concentration of 7%. Then, polyethylene oxide diamine is added to the polyvinylidene fluoride solution at 50 °C and magnetically stirred evenly at 1000 r / min to obtain a mixed solution. Among them, the mass fraction of polyethylene oxide diamine is 5% of that of polyvinylidene fluoride.

[0053] Step 2: Drop the mixed solution in Step 1 onto a glass slide and cure it into a film in a vacuum oven at 100 °C to obtain a blended polyvinylidene fluoride film.

[0054] Step 3: Place the blended polyvinylidene fluoride film obtained in Step 2 in an oven at 240 °C for cross-linking reaction to obtain a cross-linked polyvinylidene fluoride film.

[0055] Step 4: The crosslinked polyvinylidene fluoride film obtained in Step 3 is cultured at 155 °C for 10 hours to obtain a polyvinylidene fluoride film with a high γ-crystalline form content.

[0056] Example 3

[0057] Step 1: Using cyclohexanone as a solvent, a polyvinylidene fluoride solution with a mass concentration of 10% is prepared. Then, polyethylene oxide diamine is added to the polyvinylidene fluoride solution at 55 °C and magnetically stirred evenly at 2000 r / min to obtain a mixed solution. Among them, the mass fraction of polyethylene oxide diamine is 10% of that of polyvinylidene fluoride.

[0058] Step 2: The mixed solution in Step 1 is dropped onto a glass slide and cured into a film in a vacuum oven at 110 °C to obtain a blended polyvinylidene fluoride film.

[0059] Step 3: The blended polyvinylidene fluoride film obtained in Step 2 is placed in an oven at 300 °C for crosslinking reaction to obtain a crosslinked polyvinylidene fluoride film.

[0060] Step 4: The crosslinked polyvinylidene fluoride film obtained in Step 3 is cultured at 160 °C for 8 hours to obtain a polyvinylidene fluoride film with a high γ-crystalline form content.

[0061] Example 4

[0062] Step 1: Using cyclohexanone as a solvent, a polyvinylidene fluoride solution with a mass concentration of 10% is prepared. Then, polyethylene oxide diamine is added to the polyvinylidene fluoride solution at 55 °C and magnetically stirred evenly at 2000 r / min to obtain a mixed solution. Among them, the mass fraction of polyethylene oxide diamine is 15% of that of polyvinylidene fluoride.

[0063] Step 2: The mixed solution in Step 1 is dropped onto a glass slide and cured into a film in a vacuum oven at 110 °C to obtain a blended polyvinylidene fluoride film.

[0064] Step 3: The blended polyvinylidene fluoride film obtained in Step 2 is placed in an oven at 300 °C for crosslinking reaction to obtain a crosslinked polyvinylidene fluoride film.

[0065] Step 4: The crosslinked polyvinylidene fluoride film obtained in Step 3 is cultured at 165 °C for 4 hours to obtain a polyvinylidene fluoride film with a high γ-crystalline form content.

[0066] See Figure 1, which shows the Fourier transform infrared spectra of polyvinylidene fluoride films with different crosslinking degrees and high γ-crystalline content cultured at 155 °C for 4 hours. Among them, P represents the pure polyvinylidene fluoride film; 5%-P represents that the mass fraction ratio of polyethylene oxide diamine to polyvinylidene fluoride is 5:100 and crosslinking reaction has occurred; 10%-P represents that the mass fraction ratio of polyethylene oxide diamine to polyvinylidene fluoride is 10:100 and crosslinking reaction has occurred; 15%-P represents that the mass fraction ratio of polyethylene oxide diamine to polyvinylidene fluoride is 15:100 and crosslinking reaction has occurred.

[0067] See Figure 2 , which shows the Fourier transform infrared spectra of polyvinylidene fluoride films with a mass fraction ratio of polyethylene oxide diamine to polyvinylidene fluoride of 5:100 cultured at 155 °C for different times after crosslinking reaction.

[0068] Combined with Figure 1 and 2 , it can be seen that a large amount of γ-polar crystalline form can be obtained in the crosslinked polyvinylidene fluoride film within 4 hours of culturing at 155 °C, that is, a polyvinylidene fluoride film with a high γ-crystalline content is obtained.

[0069] See Figure 3 , which shows the crystallization morphology of polyvinylidene fluoride under a polarized light microscope of polyvinylidene fluoride cultured at 155 °C for 4 hours. See Figure 4 , which shows the crystallization morphology of γ-polyvinylidene fluoride under a polarized light microscope of polyvinylidene fluoride film with a mass fraction ratio of polyethylene oxide diamine to polyvinylidene fluoride of 10:100 cultured at 155 °C for 4 hours after crosslinking reaction. It can be seen that crosslinking has a significant impact on the crystallization morphology of polyvinylidene fluoride. After polyvinylidene fluoride is cultured at 155 °C for 4 hours, it forms obvious birefringence and is composed of periodic lamellae, while the crystals formed by the crosslinked polyvinylidene fluoride film show weaker birefringence and are composed of curly lamellae.

[0070] See Figure 5 , which shows the γ-crystalline content diagram (calculated from Fourier transform infrared spectroscopy data) of the crosslinked polyvinylidene fluoride film cultured at 155 °C for 4 hours. It shows that the γ-phase crystalline content of the polyvinylidene fluoride film with a mass fraction ratio of polyethylene oxide diamine to polyvinylidene fluoride of 5:100 can reach 90% after being cultured at 155 °C for 4 hours after crosslinking reaction. As the crosslinking degree increases, the γ-phase crystalline content decreases, but the content is still higher than that of pure polyvinylidene fluoride.

[0071] See Figure 6, showing the X-ray diffraction spectrogram of the crosslinked polyvinylidene fluoride film cultured at 155 °C for 4 hours. Pure polyvinylidene fluoride exhibits significant α-phase crystallization characteristic absorption peaks, including (100), (020), and (110). While the crosslinked polyvinylidene fluoride shows significant γ-phase crystallization characteristic absorption peaks, including (020) and (110). Among them, P represents the pure polyvinylidene fluoride film; 5%-P represents that the mass fraction ratio of polyethylene oxide diamine to polyvinylidene fluoride is 5:100 and crosslinking reaction occurs; 10%-P represents that the mass fraction ratio of polyethylene oxide diamine to polyvinylidene fluoride is 10:100 and crosslinking reaction occurs; 15%-P represents that the mass fraction ratio of polyethylene oxide diamine to polyvinylidene fluoride is 15:100 and crosslinking reaction occurs.

[0072] Through detection and comparison, it is found that in the polyvinylidene fluoride film based on the crosslinking reaction, under the same crystallization culture temperature and culture time, the γ-phase crystallization content of the polyvinylidene fluoride film increases significantly. At the same time, the preparation method of the polyvinylidene fluoride film based on the crosslinking reaction can replace the traditional filling method, alumina template method and high-temperature culture method, and the preparation method has simple process, convenient operation and is easy to popularize.

[0073] In another embodiment of the present invention, there is provided an application of the above-mentioned polyvinylidene fluoride film based on the crosslinking reaction in the preparation of thermistor devices.

[0074] Specifically, due to the high γ-crystalline form content, the polyvinylidene fluoride film based on the crosslinking reaction exhibits good thermal stability, mechanical strength and chemical tolerance, and also endows unique electrical properties, making this polyvinylidene fluoride film an ideal choice in many high-end technical fields.

[0075] This polyvinylidene fluoride film based on the crosslinking reaction shows great application potential in the field of pressure sensors. Its high sensitivity and stable electrical properties can accurately sense and respond to tiny pressure changes, providing a reliable guarantee for precision measurement and control. At the same time, in the field of lithium-ion batteries, as a battery separator or packaging material, this film's excellent high-temperature resistance and chemical stability effectively improve the safety and service life of the battery. In addition, this polyvinylidene fluoride film is also widely used in environments such as automotive motors that need to withstand high temperature and mechanical stress. Its excellent wear resistance and anti-aging performance ensure the stability and reliability of the motor during long-term high-speed operation. And most notably, in the preparation of high-temperature-resistant thermistor devices, this polyvinylidene fluoride film with a high γ-crystalline form content plays a crucial role. Its unique electrical properties that change significantly with temperature enable the thermistor device to accurately sense and respond to temperature changes, providing a high-precision and high-stability solution for temperature control and monitoring.

[0076] The above content is only for explaining the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a polyvinylidene fluoride film based on a cross-linking reaction, characterized in that: include: Mixing cyclohexanone, polyvinylidene fluoride and polyoxyethylene diamine to obtain a mixed solution; solidifying the mixed solution into a film to obtain a blended polyvinylidene fluoride film; The blended polyvinylidene fluoride film is subjected to a cross-linking reaction to obtain a cross-linked polyvinylidene fluoride film and cultured at 150-165° C. to obtain a polyvinylidene fluoride film with a high gamma crystal content.

2. The method for preparing a polyvinylidene fluoride film based on a cross-linking reaction according to claim 1, characterized in that: The mixing of cyclohexanone, polyvinylidene fluoride and polyoxyethylene diamine to obtain a mixed solution comprises: adding polyvinylidene fluoride to cyclohexanone to obtain a polyvinylidene fluoride solution; Polyoxyethylene diamine is added to the polyvinylidene fluoride solution to obtain a mixed solution.

3. The method for preparing a polyvinylidene fluoride film based on a cross-linking reaction according to claim 2, characterized in that: In the polyvinylidene fluoride solution, the mass concentration of polyvinylidene fluoride is 3% to 10%.

4. The method for preparing a polyvinylidene fluoride film based on a cross-linking reaction according to claim 2, characterized in that: In the mixed solution, the mass fraction of polyoxyethylene diamine is 5% to 15% of the mass fraction of polyvinylidene fluoride.

5. The method for preparing a polyvinylidene fluoride film based on a cross-linking reaction according to claim 2, characterized in that: The step of adding polyoxyethylene diamine to the polyvinylidene fluoride solution to obtain a mixed solution comprises: Add polyoxyethylene diamine to the polyvinylidene fluoride solution at 40-50° C. and stir evenly at 1000-5000 r / min to obtain a mixed solution.

6. The method for preparing a polyvinylidene fluoride film based on a cross-linking reaction according to claim 1, characterized in that: The step of curing the mixed solution into a film comprises: The mixed solution was dropped onto a glass slide and cured into a film in a vacuum oven at 90-120°C.

7. The method for preparing a polyvinylidene fluoride film based on a cross-linking reaction according to claim 1, characterized in that: The cross-linking reaction of the blended polyvinylidene fluoride film comprises: The blended polyvinylidene fluoride film is subjected to a cross-linking reaction at 180-300°C.

8. The method for preparing a polyvinylidene fluoride film based on a cross-linking reaction according to claim 1, characterized in that: The method of obtaining a cross-linked polyvinylidene fluoride film and culturing the film at 150-165° C. comprises: A cross-linked polyvinylidene fluoride film is obtained and cultured at 150-165° C. for 4-18 hours.

9. A polyvinylidene fluoride film based on a cross-linking reaction, characterized in that: The polyvinylidene fluoride film is prepared by the method for preparing a polyvinylidene fluoride film based on a cross-linking reaction as described in any one of claims 1 to 8.

10. Use of the cross-linking reaction-based polyvinylidene fluoride film according to claim 9 in preparing a thermistor device.

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