Polyacrylonitrile fiber composite piezoelectric material and preparation method thereof

Abstract

This invention relates to the field of composite piezoelectric materials, and more particularly to a polyacrylonitrile fiber composite piezoelectric material and its preparation method. The preparation method provided by this invention first utilizes a coating method to prepare a composite fiber membrane. The interfacial interaction—microphase synergy effect—formed by the coating between the EP matrix and the piezoelectric active layer effectively suppresses the random entanglement and thermal relaxation of the molecular chains in the piezoelectric active layer. Subsequently, corona polarization is used to induce the molecular chains of the piezoelectric active layer to oriented along the electric field direction, which can significantly increase the proportion of the planar serrated conformation of the piezoelectric active layer. This preparation method has strong process compatibility, controllable preparation cost, and is suitable for large-scale industrial production. The prepared composite piezoelectric material does not require complex multilayer structures or additional doping modifications to achieve directional improvement and long-term stability of the piezoelectric coefficient, and has excellent reusability, which is expected to meet the needs of diverse application scenarios.

Description

Technical Field

[0001] This invention relates to the field of composite piezoelectric materials technology, and in particular to a polyacrylonitrile fiber composite piezoelectric material and its preparation method. Background Technology

[0002] In recent years, energy harvesting technologies, represented by piezoelectricity, triboelectricity, and pyroelectricity, have made some progress. Among them, piezoelectric materials, due to their unique piezoelectric effect, can convert mechanical energy from the surrounding environment into electrical energy and are considered potential materials for the fabrication of portable electronic devices.

[0003] Currently, organic piezoelectric materials such as polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF) and its copolymers, and polylactic acid (PLA) are frequently used to fabricate flexible piezoelectric nanodevices due to their small size, light weight, high flexibility, renewability, low cost, low impedance, and good biocompatibility. Among these, polyacrylonitrile is a quasi-crystalline polymer with -CH2-CH(CN)- as repeating units, exhibiting planar serrated and 3-phase crystal structures. 1 PAN exhibits two different helical conformations. The planar zigzag conformation, due to its all-trans structure, displays a 3.5 Debye dipole moment, higher than PVDF. Based on this, PAN demonstrates a superior piezoelectric response compared to PVDF. However, due to the strong electronegativity of the nitrile groups, strong dipole-dipole repulsion exists between and within molecules, resulting in PAN's inherent stability at 3... 1 Helical conformation. In 3 1 In the helical conformation, the dipoles cancel each other out, limiting its ability to convert mechanical energy into electrical energy. Furthermore, due to a lack of effective processing techniques, it is difficult to process PAN into high-performance piezoelectric materials. For these reasons, previous research on the piezoelectric properties of PAN has been relatively limited.

[0004] Epoxy resin (EP) possesses excellent mechanical properties, good chemical stability, and processability. The epoxy groups and hydroxyl groups in its molecular chain can form a three-dimensional cross-linked network through a curing reaction, endowing the material with high structural stability and fatigue resistance. However, it does not possess piezoelectric activity itself and relies on a piezoelectric phase to impart functionality. This limits the piezoelectric properties of the composite material to the uniformity of dispersion. High cross-linking restricts molecular chain movement, making it prone to embrittlement at low temperatures, affecting the stability of piezoelectric response under extreme conditions. Volume shrinkage during curing may introduce internal stress, disrupting the polarization domain structure and reducing the overall piezoelectric coefficient.

[0005] Therefore, how to develop a composite piezoelectric material that is easy to operate, inexpensive to prepare, and has stable piezoelectric properties is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in the related art. Therefore, the first objective of the present invention is to provide a method for preparing a polyacrylonitrile fiber composite piezoelectric material; the second objective of the present invention is to provide a polyacrylonitrile fiber composite piezoelectric material.

[0007] To achieve the first objective, the technical solution adopted by this invention is as follows:

[0008] A method for preparing a polyacrylonitrile fiber composite piezoelectric material includes the following steps:

[0009] S100. Epoxy resin is coated onto the surface of the piezoelectric active layer using a coating method, and then dried to obtain a composite fiber membrane.

[0010] The piezoelectric active layer is selected from any one of the following materials: polyacrylonitrile fiber, polyvinylidene fluoride, polyvinylidene fluoride copolymer, or polylactic acid.

[0011] The thickness of the composite fiber membrane is 0.3 mm to 0.9 mm;

[0012] S200. The composite fiber membrane is subjected to corona polarization treatment to obtain a polyacrylonitrile fiber composite piezoelectric material.

[0013] The parameter settings during the corona polarization process are as follows:

[0014] The polarization voltage is 9kV to 17kV, the polarization temperature is 80℃ to 130℃, and the polarization time is 10min to 40min.

[0015] Preferably, in step S100, the piezoelectric active layer is selected from polyacrylonitrile fiber, and the thickness of the composite fiber membrane is 0.3 mm to 0.4 mm.

[0016] In step S200, the polarization voltage is 10.5kV to 11.5kV, the polarization temperature is 119℃ to 121℃, and the polarization time is 19min to 21min.

[0017] A polyacrylonitrile-epoxy resin composite fiber membrane was prepared by coating epoxy resin (EP) onto polyacrylonitrile (PAN) using a coating method. The composite fiber membrane was then treated with corona polarization to enhance the proportion of piezoelectric active molecular conformations and charge separation efficiency of the polyacrylonitrile molecules. This process resulted in a stable and ordered dipole orientation of the composite material during polarization, significantly improving charge retention and electromechanical coupling response. This enhanced the piezoelectric coefficient and energy conversion efficiency, achieving a targeted improvement in piezoelectric performance while maintaining excellent interfacial bonding strength.

[0018] The piezoelectricity of composite materials needs to be activated through polarization treatment (applying an external electric field). The core of this is to achieve the directional alignment of the -CN dipoles in the PAN, which is mainly reflected in three aspects:

[0019] I. Electric Field-Induced Dipole Orientation: Under the action of polarization voltage (9kV~17kV), the -CN dipoles in the PAN molecular chain overcome the intramolecular rotational resistance and the steric hindrance of the EP matrix, and gradually orient themselves along the direction of the electric field. Because the polar groups of EP have relatively weak dipole moments, they mainly assist in the transmission of the electric field with the deformation of the matrix, thereby reducing the energy barrier for PAN dipole orientation.

[0020] II. Interfacial Co-polarization: At the interface between PAN and EP, the polar groups of both form an interfacial dipole layer through dipole coupling. This layer can amplify the local electric field intensity and promote the orientation of nearby -CN groups.

[0021] III. Polarization Locking: After polarization, the cross-linked network of EP "locks" the dipole orientation of PAN through mechanical constraints, thereby improving the piezoelectric properties of the composite material.

[0022] This invention improves the piezoelectric properties of the composite fiber membrane by controlling the polarization voltage, polarization temperature, and polarization time to increase the content of the planar serrated phase. Furthermore, by coordinating the synergistic relationship between the composite fiber membrane thickness, device geometry, electrode type, and friction protection, the uniformity and effectiveness of corona polarization are ensured, further enhancing the piezoelectric performance.

[0023] Preferably, in step S100, the coating method is selected from any one of solution coating, electrostatic spraying, dip coating, layer coating, and in-situ coating. These coating methods can precisely control the coating thickness, interfacial bonding, and molecular orientation regularity of the epoxy resin (EP) matrix and the polyacrylonitrile (PAN) piezoelectric active component, providing diversified process routes for preparing EP-PAN composite fibers with excellent piezoelectric response, interfacial stability, and mechanical properties, which is beneficial for improving polarization efficiency and charge retention capacity.

[0024] Preferably, the solution coating uses an epoxy resin organic solution to coat the polyacrylonitrile fibers, wherein the solvent of the epoxy resin organic solution is selected from acetone.

[0025] Preferably, in step S100, the volume ratio of epoxy resin to acetone in the epoxy resin organic solution is 1:3 to 2:3.

[0026] Preferably, in step S100, a metal layer is attached to or vapor-deposited onto the surface of the composite fiber membrane.

[0027] Preferably, the metal layer is selected from a gold layer or a nickel layer.

[0028] Preferably, in step S100, the area of ​​the composite fiber membrane is 3cm×3cm to 5cm×5cm.

[0029] Preferably, in step S200, the corona polarization is selected from grid polarization or oil bath polarization.

[0030] To achieve the second objective, the technical solution adopted by this invention is as follows:

[0031] A polyacrylonitrile fiber composite piezoelectric material is prepared using any one of the above-described methods for preparing polyacrylonitrile fiber composite piezoelectric materials.

[0032] Preferably, the material is used to prepare a piezoelectric device, wherein the piezoelectric device has a sandwich structure, and the layer order is PET film, aluminum foil, polyacrylonitrile fiber composite piezoelectric material, aluminum foil and PET film in sequence.

[0033] PET stands for polyethylene terephthalate.

[0034] The polyacrylonitrile fiber composite piezoelectric material provided by this invention, based on its excellent piezoelectric response, interface stability, and mechanical compatibility, is expected to achieve efficient coupling and conversion of mechanical signals and electrical energy. This material is widely applicable to the fabrication of various piezoelectric functional products such as flexible pressure sensors, wearable piezoelectric devices, micro energy harvesters, and vibration monitoring sensors, and can be adapted to diverse application scenarios such as flexible electronics, intelligent sensing, and power supply for low-power devices.

[0035] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0036] This invention provides a method for preparing a polyacrylonitrile fiber composite piezoelectric material. First, a composite fiber membrane is prepared using a coating method. The "interface interaction-microphase synergistic effect" formed by the coating of the EP matrix and the piezoelectric active layer can effectively suppress the random entanglement and thermal relaxation of the molecular chains in the piezoelectric active layer. Subsequently, corona polarization is used to induce the molecular chains of the piezoelectric active layer to oriented along the electric field direction, which can significantly increase the proportion of the planar serrated conformation of the piezoelectric active layer.

[0037] Furthermore, after polarization treatment (polarization voltage 11kV, polarization time 20min, polarization temperature 120℃), the voltage of the composite fiber membrane reached 126V, approximately 8.4 times that of the unpolarized composite fiber membrane. This demonstrates a very high correlation between polarization and the piezoelectricity of the composite fiber membrane. The piezoelectric current of the polarized EP-PAN composite fiber membrane increased from 4.8μA to 34.2μA, indicating that polarization can promote an increase in the content of planar serrated conformations within the fiber membrane, thereby improving its piezoelectric performance.

[0038] The preparation method provided by this invention has strong process compatibility and controllable preparation cost, making it suitable for large-scale industrial production.

[0039] This invention presents a composite fiber membrane prepared by a coating method. Through a synergistic design of "EP matrix dielectric regulation - interfacial covalent bonding - corona polarization adaptation," the proportion of piezoelectric active conformations of piezoelectric active molecules is significantly enhanced. This composite fiber membrane achieves directional enhancement and long-term stability of the piezoelectric coefficient without complex multilayer structures or additional doping modifications. Furthermore, corona polarization enhances piezoelectric performance, resulting in excellent reusability. The piezoelectric material provided by this invention can be widely adapted to piezoelectric functional products such as flexible pressure sensors, industrial vibration monitoring devices, and low-power energy harvesting equipment, and is expected to be applied in diverse application scenarios such as intelligent sensing and flexible electronics.

[0040] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0041] Figure 1 The image shows the infrared test results of EP-PAN and EP-PAN-11kV provided in Embodiment 1 of the present invention.

[0042] Figure 2 These are the X-ray diffraction (XRD) patterns of EP-PAN and EP-PAN-11kV provided in Embodiment 1 of the present invention.

[0043] Figure 3 This is a dynamic thermal analysis result diagram of EP-PAN and EP-PAN-11kV provided in Embodiment 1 of the present invention.

[0044] Figure 4 This is a schematic diagram of the structure of the piezoelectric device provided in Embodiment 1 of the present invention.

[0045] Figure 5 This is the electrical output performance test curve of the piezoelectric device provided in Embodiment 1 of the present invention.

[0046] Figure 6 The results are the test results of the piezoelectric constants of EP-PAN and EP-PAN-11kV provided in Embodiment 1 of the present invention.

[0047] Figure 7 These are the test results of the dielectric properties of EP-PAN and EP-PAN-11kV provided in Embodiment 1 of the present invention.

[0048] Figure 8 The results are infrared test results of composite piezoelectric materials polarized with different polarization voltages provided in Screening Example 1 of this invention.

[0049] Figure 9These are the test results of the piezoelectric properties of the composite piezoelectric materials polarized with different polarization voltages provided in Screening Example 1 of this invention.

[0050] Figure 10 The results are the test results of the piezoelectric constants of the composite piezoelectric materials polarized with different polarization voltages provided in Screening Example 1 of this invention.

[0051] Figure 11 The results are infrared test results of composite piezoelectric materials polarized at different polarization temperatures provided in Screening Example 2 of this invention.

[0052] Figure 12 These are the test results of the piezoelectric properties of the composite piezoelectric materials polarized at different polarization temperatures provided in Screening Example 2 of this invention.

[0053] Figure 13 The results are the test results of the piezoelectric constants of the composite piezoelectric materials polarized at different polarization temperatures provided in Screening Example 2 of this invention.

[0054] Figure 14 The results are infrared test results of composite piezoelectric materials polarized at different polarization times, as provided in Screening Example 3 of this invention.

[0055] Figure 15 These are the test results of the piezoelectric properties of the composite piezoelectric materials polarized at different polarization times provided in Screening Example 3 of this invention.

[0056] Figure 16 These are the test results of the piezoelectric constants of the composite piezoelectric materials polarized at different polarization times provided in Screening Example 3 of this invention.

[0057] Figure 17 This is a voltage-time curve of a piezoelectric device made from composite piezoelectric materials of different thicknesses, provided in Screening Example 4 of the present invention.

[0058] Figure 18 This is a voltage-time curve of a piezoelectric device made using electrode materials of different materials, provided in Screening Example 5 of this invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention, but cannot be used to limit the scope of this invention.

[0060] In the following embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available, and are carried out in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0061] Example 1

[0062] I. Preparation of Epoxy Resin-Polyacrylonitrile (EP-PAN) Composite Fiber Membrane: Two aluminum plates of the same size were selected, and a layer of polytetrafluoroethylene film was coated on their surfaces. Then, polyacrylonitrile fibers were wound onto one of the aluminum plates using a single-layer parallel winding method. After winding, a pre-prepared epoxy resin-acetone solution (prepared by dissolving 8 mL of epoxy resin in 12 mL of acetone) was taken and evenly coated onto the surface of the polyacrylonitrile fibers with a brush, ensuring that the epoxy resin-acetone solution fully wetted the fibers. Then, the two aluminum plates were fixed together with clamps, so that the epoxy resin-acetone solution coating was between the two aluminum plates. The fixed aluminum plates were dried in an environment of 50°C for 2 hours. Finally, the aluminum plates were removed to obtain the EP-PAN composite fiber membrane, denoted as EP-PAN.

[0063] II. The EP-PAN composite fiber membrane was polarized as follows: The EP-PAN composite fiber membrane was cut into 3cm×3cm samples. The membrane sample was gently placed in the center of the lower electrode, and then the grid was fixed on the sample. The synchronous polarization method was adopted, the polarization voltage was set to 11kV, and the polarization temperature was raised from room temperature to 120℃. After maintaining the polarization at 120℃ for 20min, the sample was slowly cooled to room temperature (30℃) under the applied electric field (maintained by an 11kV potential difference) to obtain the polarized EP-PAN composite fiber membrane, i.e., polyacrylonitrile composite piezoelectric material, denoted as EP-PAN-11kV.

[0064] III. Testing of the composite fiber membrane before and after polarization:

[0065] (I) Infrared testing.

[0066] The absorbance of the samples was measured using a Fourier transform infrared spectrometer (FTIR, manufacturer: Thermo Fisher Scientific, model: Nicoleti S50, China). The test mode was ATR mode, and the wavenumber range was 400–4000 cm⁻¹. -1 The test results are as follows Figure 1 As shown;

[0067] Figure A shows the Fourier Transform Infrared (FTIR) spectra of the composite fiber membrane before and after polarization. The 1250 cm⁻¹ value in this figure... -1 and 1230cm -1 The vibration bands at these locations correspond to the serrated conformation and 3, respectively. 1 Helical conformation;

[0068] Figure B shows the serrated conformation content of the composite fiber membrane before and after polarization. From the figure, it can be seen that the serrated conformation content (Φ) of the EP-PAN-11kV fiber membrane is 78.7%, which is significantly higher than that of the unpolarized EP-PAN (55.9%).

[0069] The formula for calculating Φ is as follows:

[0070] ;

[0071] Among them, S 1230 and S 1250 It is 1230cm -1 and 1250cm -1 Peak area at that location.

[0072] (II) Detection of crystal structure.

[0073] The crystal structure of the sample was determined by X-ray diffraction (XRD, manufacturer: BRUKER, model: D8 DISCOVER, Germany). The XRD target was a copper target (wavelength: 1.54060 Å), the scanning angle range was 5°–45°, and the scanning speed was 2° / min. The test results are as follows: Figure 2 As shown in the figure, it can be seen that for PAN fibers, two sharp diffraction peaks were observed at approximately 2θ≈17.2° and 2θ≈29.8°. This is related to the (100) and (110) lattice planes caused by the strong dipole-dipole interaction between C≡N groups in the PAN precursor fibers. The diffraction peak at 2θ≈17.2° of the polarized composite fiber membrane is sharper and has a higher intensity than the peak at 2θ≈29.8° compared to the previous peak. Since the (110) crystal plane direction flattens the oblique arrangement of PAN molecular chains, it exhibits a regular and ordered arrangement in three-dimensional space. The existence of these two crystal planes confirms that the PAN solid has a certain degree of crystallinity. The peak shape of the (100) crystal plane is sharper, indicating that EP-PAN-11kV has a higher degree of crystallinity, that is, the molecular arrangement is more ordered and has a regular in-plane arrangement. This result shows that the planar serrated conformation content of the polarized sample EP-PAN-11kV is greater than that of PAN, which in turn affects the piezoelectric properties of the fiber membrane.

[0074] (III) Dynamic thermal analysis.

[0075] The elastic modulus and loss tangent of the material were tested using a dynamic thermomechanical analyzer (NETZSCH, model: DMA242E). The elastic modulus and loss tangent were tested using a three-point bending mode at a frequency of 1 Hz, a load amplitude of 0.5 N, and a test temperature of 30℃~20℃ (air environment). The test results are as follows: Figure 3 As shown;

[0076] Figure A shows the energy storage modulus (E') of EP-PAN and EP-PAN-11kV as a function of temperature. It can be seen from the figure that in the range of 40 to 120℃, the E' of EP-PAN-11kV (after polarization) is significantly higher than that of the unpolarized EP-PAN.

[0077] Figure B shows the loss factor curves of EP-PAN and EP-PAN-11kV as a function of temperature. From this figure, it can be seen that the 11kV polarization voltage can induce the PAN cyano groups to align in an orderly manner along the electric field direction, forming a "dipole array." As the peak temperature of the loss factor increases, the dynamic glass temperature (Tg) of the EP-PAN-11kV sample increases by 7℃ compared to the unpolarized sample (108℃), because the chain segment movement in the ordered structure needs to overcome a higher energy barrier.

[0078] (iv) Testing of piezoelectric properties.

[0079] Sandwich piezoelectric devices are fabricated using composite fiber membranes, such as Figure 4 As shown, the sandwich piezoelectric device has a symmetrical sandwich encapsulation structure, with the following layer order: polyethylene terephthalate (PET) film (80 μm thick), aluminum foil (0.2 mm thick), composite fiber film (3 cm × 3 cm, 0.3 mm), aluminum foil (0.2 mm thick), and PET film (80 μm thick).

[0080] Two aluminum foils are in direct contact with the composite fiber membrane and are used as electrodes for electrocollection.

[0081] As an encapsulation protective layer, the PET film layer has transparency (for observing the internal structure), excellent insulation (to prevent collector leakage and avoid electrical signal loss), good flexibility (to compress and deform synchronously with the device without hindering energy transfer), and strong weather resistance (to protect the internal fiber film and aluminum foil from moisture and oxidation).

[0082] The electrical output characteristics of this sandwich-type piezoelectric device under repeated compression and decompression impacts (frequency 1 Hz, force 3000 N) were measured using an electric meter. The measurement results are as follows: Figure 5 ;

[0083] Figure A shows the voltage of the piezoelectric device over time. From this figure, we can see that the voltage of the polarized composite fiber membrane is 126V, which is about 8.4 times that of the unpolarized composite fiber membrane. This result proves that polarization has a high influence on the piezoelectricity of the composite fiber membrane.

[0084] Figure B shows the curve of the piezoelectric device current changing over time. From this figure, it can be seen that the piezoelectric current of the polarized EP-PAN composite fiber membrane increased from the original 4.8 μA to 34.2 μA. This result indicates that the energy output capability of the piezoelectric device is greatly improved after polarization.

[0085] (v) Testing of piezoelectric constant.

[0086] The 1-10000PC / NPM300 electret nonwoven piezoelectric performance testing system, purchased from Tianjin INNEIS Technology Co., Ltd. by a UK piezoelectric design company, was used. The test results are as follows: Figure 6 As shown in the figure, it can be seen that the piezoelectric constant of the polarized composite fiber membrane is significantly improved compared with that of the unpolarized composite fiber membrane.

[0087] (vi) Testing of dielectric properties.

[0088] The dielectric constant and dielectric loss of the EP-PAN composite fiber film were tested using a dielectric constant meter (model: Agilent 4294A). The test frequency range was 1kHz to 1MHz. The test results are as follows: Figure 7 ;

[0089] Figure A shows the dielectric constant of EP-PAN and EP-PAN-11kV as a function of frequency. It can be seen from the figure that the dielectric constant of EP-PAN-11kV (after polarization) is significantly higher than that of the unpolarized EP-PAN.

[0090] Figure B shows the dielectric loss curves of EP-PAN and EP-PAN-11kV as a function of frequency. From this figure, it can be seen that in the high-frequency range (10... 4 Hz~10 6 The dielectric loss of the unpolarized EP-PAN (Hz) is significantly higher than that of the polarized EP-PAN-11kV.

[0091] Screening Example 1

[0092] This screening example examines the effects of different polarization voltages (9KV, 11KV, 13KV, 15KV, and 17KV) on the performance of the composite piezoelectric material under otherwise unchanged conditions (same as Example 1).

[0093] Depending on the polarization voltage, the prepared polyacrylonitrile composite piezoelectric materials are designated as EP-PAN-9kV, EP-PAN-11kV, EP-PAN-13kV, EP-PAN-15kV, and EP-PAN-17kV, respectively.

[0094] I. Infrared testing.

[0095] The testing process is the same as in Example 1, and the test results are as follows: Figure 8As shown;

[0096] Figure A shows the infrared test results of the composite fiber membranes after unpolarization and treatment with different polarization voltages. From this figure, it can be seen that the peak shape and absorption intensity of the spectral curves under different polarization voltages are different, indicating that the polarization voltage will change the chemical functional group structure of the EP-PAN material.

[0097] Figure B shows the serrated conformation content of the composite fiber membrane after treatment with different polarization voltages. From this figure, it can be seen that when the polarization voltages are 9 kV, 11 kV, 13 kV, 15 kV, and 17 kV, the Φ values ​​of the polarized EP-PAN composite fiber membranes are 57.2%, 78.7%, 70.2%, 57.7%, and 56.9%, respectively. With increasing polarization voltage, the planar serrated phase content of the EP-PAN composite fiber membrane shows a trend of first increasing and then decreasing, with the Φ value reaching its highest value when the polarization voltage is 11 kV.

[0098] II. Testing of piezoelectric properties.

[0099] The testing process is the same as in Example 1, and the test results are as follows: Figure 9 As shown;

[0100] Figure A shows the voltage of the piezoelectric device over time, and Figure B shows the current of the piezoelectric device over time.

[0101] from Figure 9 It can be seen that when the polarization voltages are 9kV, 11kV, 13kV, 15kV and 17kV, the piezoelectric voltages are 82.8V, 126.0V, 107.9V, 93.2V and 92.9V, respectively, and the piezoelectric currents are 25.5μA, 34.2μA, 24.1μA, 21.3μA and 20.7μA, respectively. This result shows that the piezoelectric performance of the polarized composite fiber membrane reaches its optimal state when the polarization voltage is 11kV.

[0102] (III) Testing of piezoelectric constant.

[0103] The testing process is the same as in Example 1, and the test results are as follows: Figure 10 As shown in the figure, it can be seen that when the polarization voltage is 11kV, the piezoelectric constant of the polarized composite fiber membrane reaches the optimal state.

[0104] Screening Example 2

[0105] This screening example examines the effects of different polarization temperatures of 80°C, 90°C, 100°C, 110°C, 120°C, and 130°C on the properties of the composite piezoelectric material, under otherwise unchanged conditions (same as Example 1).

[0106] Depending on the polarization temperature, the prepared polyacrylonitrile composite piezoelectric materials are designated as EP-PAN-80℃, EP-PAN-90℃, EP-PAN-100℃, EP-PAN-110℃, EP-PAN-120℃, and EP-PAN-130℃, respectively.

[0107] I. Infrared testing.

[0108] The testing process is the same as in Example 1, and the test results are as follows: Figure 11 As shown;

[0109] Figure A shows the infrared test results of the composite fiber membranes after unpolarization and treatment at different polarization temperatures. From this figure, it can be seen that the peak shape and absorption intensity of the spectral curves at different polarization temperatures are different, indicating that the polarization temperature will change the chemical functional group structure of the EP-PAN material.

[0110] Figure B shows the serrated conformation content of the composite fiber membrane after treatment at different polarization temperatures. From this figure, it can be seen that when the polarization temperatures are 90℃, 100℃, 110℃, 120℃, and 130℃, the Φ values ​​of the polarized EP-PAN composite fiber membranes are 59.6%, 60.8%, 64.7%, 78.7%, and 58.1%, respectively. With increasing polarization temperature, the planar serrated phase content of the EP-PAN composite fiber membrane first increases and then decreases, with the Φ value reaching its highest value at a polarization temperature of 120℃.

[0111] II. Testing of piezoelectric properties.

[0112] The testing process is the same as in Example 1, and the test results are as follows: Figure 12 As shown;

[0113] Figure A shows the voltage of the piezoelectric device over time, and Figure B shows the current of the piezoelectric device over time.

[0114] from Figure 12 It can be seen that when the polarization temperatures are 80℃, 90℃, 100℃, 110℃, 120℃, and 130℃, the piezoelectric voltages are 54.2V, 75.1V, 80.6V, 99.1V, 126.0V, and 74.9V, respectively, and the piezoelectric currents are 20.9μA, 23.8μA, 26.4μA, 27.3μA, 34.2μA, and 23.5μA, respectively. Furthermore, the piezoelectric performance of the polarized composite fiber membrane is significantly higher than that of the unpolarized composite fiber membrane. The piezoelectric performance of the polarized composite fiber membrane reaches its optimal state when the polarization temperature is 120℃.

[0115] III. Testing of piezoelectric constant.

[0116] The testing process is the same as in Example 1, and the test results are as follows: Figure 13As shown in the figure, it can be seen that the piezoelectric constant of the polarized composite fiber membrane reaches its optimal state when the polarization temperature is 120℃.

[0117] Screening Example 3

[0118] This screening example examines the effect of different polarization times of 10 min, 20 min, 30 min, 40 min and 50 min on the properties of the composite piezoelectric material under otherwise unchanged conditions (same as Example 1).

[0119] Depending on the polarization time, the prepared polyacrylonitrile composite piezoelectric materials are designated as EP-PAN-10min, EP-PAN-20min, EP-PAN-30min, EP-PAN-40min, and EP-PAN-50min, respectively.

[0120] I. Infrared testing.

[0121] The testing process is the same as in Example 1, and the test results are as follows: Figure 14 As shown;

[0122] Figure A shows the infrared test results of the composite fiber membrane after unpolarization and different polarization times. From this figure, it can be seen that the peak shape and absorption intensity of the spectral curves under different polarization times are different, indicating that the polarization time will change the chemical functional group structure of the EP-PAN material.

[0123] Figure B shows the serrated conformation content of the composite fiber membrane after different polarization times. From the figure, it can be seen that when the polarization time is 10 min, 20 min, 30 min and 40 min respectively, the Φ value of the EP-PAN composite fiber membrane is 59.1%, 78.7%, 68.2% and 61.4% respectively. As the polarization time increases, the Φ value of the EP-PAN fiber membrane device first increases and then decreases, indicating that excessively high polarization time will reduce the planar serrated phase content of the device. The Φ value of the polarized composite fiber membrane reaches the highest value when the polarization time is 20 min.

[0124] II. Testing of piezoelectric properties.

[0125] The testing process is the same as in Example 1, and the test results are as follows: Figure 15 As shown;

[0126] Figure A shows the voltage of the piezoelectric device over time, and Figure B shows the current of the piezoelectric device over time.

[0127] from Figure 15It can be seen that when the polarization time is 10 min, 20 min, 30 min, 40 min, and 50 min, the piezoelectric voltage is 74.8 V, 126.0 V, 85.3 V, 77.3 V, and 57.9 V, respectively, and the piezoelectric current is 20.1 μA, 34.2 μA, 26.5 μA, 26.1 μA, and 17.8 μA, respectively. The piezoelectric performance of the polarized composite fiber membrane is significantly higher than that of the unpolarized composite fiber membrane. The piezoelectric performance of the polarized composite fiber membrane reaches its optimal state when the polarization time is 20 min.

[0128] III. Testing of piezoelectric constant.

[0129] The testing process is the same as in Example 1, and the test results are as follows: Figure 16 As shown in the figure, it can be seen that the piezoelectric constant of the polarized composite fiber membrane reaches its optimal state when the polarization time is 20 min.

[0130] Screening Example 4

[0131] This screening example examines whether the piezoelectric properties of composite piezoelectric materials with different thicknesses (0.3 mm, 0.6 mm, and 0.9 mm, respectively) differ under otherwise unchanged conditions (same as Example 1).

[0132] Depending on the thickness, the prepared polyacrylonitrile composite piezoelectric materials are designated as EP-PAN-0.3mm, EP-PAN-0.6mm, and EP-PAN-0.9mm, respectively.

[0133] The piezoelectric properties were tested according to the test procedure in Example 1, and the test results are as follows: Figure 17 As shown in the figure, it can be seen that piezoelectric devices made of composite piezoelectric materials of different thicknesses have different output voltages, and the piezoelectric performance reaches the optimal state when the film thickness is 0.3 mm.

[0134] Screening Example 5

[0135] The effects of electrodes with different materials (aluminum, gold, and nickel) on the piezoelectric properties of the prepared piezoelectric device were examined under the condition that other conditions remain unchanged (same as in Example 1).

[0136] Depending on the type of electrode, piezoelectric devices are designated as EP-PAN-aluminum, EP-PAN-gold, and EP-PAN-nickel.

[0137] The piezoelectric properties were tested according to the test procedure in Example 1, and the test results are as follows: Figure 18 As shown in the figure, it can be seen that when gold is used as the electrode for electric collection, the piezoelectric performance reaches its optimal state.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing a polyacrylonitrile fiber composite piezoelectric material, characterized by, Includes the following steps: S100. Epoxy resin is coated onto the surface of the piezoelectric active layer using a coating method, and then dried to obtain a composite fiber membrane. The piezoelectric active layer is selected from polyacrylonitrile fiber; The thickness of the composite fiber membrane is 0.3 mm to 0.9 mm; S200. The composite fiber membrane is subjected to corona polarization treatment to obtain a polyacrylonitrile fiber composite piezoelectric material. The parameter settings during the corona polarization process are as follows: The polarization voltage is 9kV to 17kV, the polarization temperature is 80℃ to 130℃, and the polarization time is 10min to 40min.

2. The method for preparing the polyacrylonitrile fiber composite piezoelectric material as described in claim 1, characterized in that, In step S100, the thickness of the composite fiber membrane is 0.3 mm to 0.4 mm; In step S200, the polarization voltage is 10.5kV to 11.5kV, the polarization temperature is 119℃ to 121℃, and the polarization time is 19min to 21min.

3. The method for preparing the polyacrylonitrile fiber composite piezoelectric material as described in claim 1, characterized in that, In step S100, the coating method is selected from electrostatic spraying or dip coating.

4. The method for preparing the polyacrylonitrile fiber composite piezoelectric material as described in claim 3, characterized in that, Solution coating involves coating polyacrylonitrile fibers with an epoxy resin organic solution, wherein the solvent of the epoxy resin organic solution is selected from acetone.

5. The method for preparing the polyacrylonitrile fiber composite piezoelectric material as described in claim 4, characterized in that, In step S100, the volume ratio of epoxy resin to acetone in the epoxy resin organic solution is 1:3 to 2:

3.

6. The method for preparing the polyacrylonitrile fiber composite piezoelectric material as described in claim 1, characterized in that, In step S100, a metal layer is attached to or deposited on the surface of the composite fiber membrane, wherein the metal layer is a gold layer or a nickel layer.

7. The method for preparing the polyacrylonitrile fiber composite piezoelectric material as described in claim 1, characterized in that, In step S100, the area of ​​the composite fiber membrane is 3cm×3cm to 5cm×5cm.

8. A polyacrylonitrile fiber composite piezoelectric material, characterized in that, It is prepared using the preparation method of polyacrylonitrile fiber composite piezoelectric material as described in any one of claims 1 to 7.

9. The polyacrylonitrile fiber composite piezoelectric material as described in claim 8, characterized in that, Used to prepare piezoelectric devices, wherein the piezoelectric devices have a sandwich structure, and the layer order is PET film, aluminum foil, polyacrylonitrile fiber composite piezoelectric material, aluminum foil and PET film in sequence; PET stands for polyethylene terephthalate.

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