Preparation method of piezoelectric fiber membrane, piezoelectric fiber membrane and application

Abstract

The invention discloses a preparation method of a piezoelectric fiber membrane, the piezoelectric fiber membrane and application, the method comprises the following steps: adding polyethylene glycol into a dipole aprotic solvent, and stirring until the polyethylene glycol is completely dissolved to obtain a first mixed solution; sequentially adding a polyurethane material and a piezoelectric polymer into the first mixed solution, and stirring at a first preset temperature for a first preset duration to obtain a second mixed solution; adding the second mixed solution into an electrostatic spinning device for electrostatic spinning to obtain a spinning membrane; the spinning membrane is sequentially subjected to drying, soaking, cleaning and drying treatment, and the piezoelectric fiber membrane is obtained. The prepared piezoelectric fiber membrane has good piezoelectric performance, can enhance the guiding effect on piezoelectric charges, and can improve the scale inhibition effect when being used as a filter membrane.

Description

Technical Field

[0001] The present invention relates to the technical field of functional materials, and in particular to a preparation method of a piezoelectric fiber membrane, a piezoelectric fiber membrane and applications thereof. Background Art

[0002] During the use of a water purifier, scale will gradually form and adhere to the surface of the filter membrane of the water purifier filter element, blocking the pores of the filter membrane, rapidly reducing the membrane flux and losing its separation function. The main source of scale is charged particles such as calcium, magnesium, and bicarbonate in the water. In the existing technology, the preparation process of filter membranes with scale inhibition function usually involves adding chemical scale inhibitors to the raw materials of the filter membrane to prevent scale from forming or adhering to the filter membrane surface. However, chemical scale inhibitors are mostly phosphorus-based, which has a significant impact on water eutrophication and can easily cause secondary pollution of drinking water. In addition, long-term immersion of scale inhibitors may cause powdering, producing white powdery precipitates, which in turn causes filter membrane clogging. Summary of the Invention

[0003] To address the aforementioned issues in the prior art, the present invention discloses a method for preparing a piezoelectric fiber membrane, a piezoelectric fiber membrane, and its application. The piezoelectric fiber membrane prepared by this method has good piezoelectric properties, enhances the guiding effect of piezoelectric charges, and can improve the scale inhibition effect when used as a filter membrane. The technical solutions disclosed in the present invention are as follows:

[0004] According to one aspect of the disclosed embodiments of the present invention, a method for preparing a piezoelectric fiber membrane is provided, comprising:

[0005] adding polyethylene glycol to a dipolar aprotic solvent and stirring until the polyethylene glycol is completely dissolved to obtain a first mixed solution;

[0006] adding a polyurethane material and a piezoelectric polymer to the first mixed solution in sequence, and stirring at a first preset temperature for a first preset time to obtain a second mixed solution; wherein the mass ratio of the polyethylene glycol, the polyurethane material, and the piezoelectric polymer is (0.5-1):(0.5-1):(8-9), the volume ratio of the mass of the polyethylene glycol to the dipolar aprotic solvent, and the volume ratio of the mass of the polyurethane material to the dipolar aprotic solvent are 0.006 g / ml to 0.012 g / ml, and the volume ratio of the mass of the piezoelectric polymer to the dipolar aprotic solvent is 0.096 g / ml to 0.108 g / ml;

[0007] adding the second mixed solution into an electrospinning device for electrospinning to obtain a spinning membrane;

[0008] The spinning membrane is sequentially dried, soaked, cleaned and dried to obtain a piezoelectric fiber membrane.

[0009] Optionally, the electrospinning device includes a coaxial electrospinning device, and before adding the second mixed solution to the electrospinning device for electrospinning to obtain a spinning membrane, the method further includes:

[0010] adding polyethylene glycol to the ethanol solution and stirring until the polyethylene glycol is completely dissolved to obtain a third mixed solution;

[0011] The step of adding the second mixed solution into an electrospinning device for electrospinning to obtain a spinning membrane comprises:

[0012] adding the second mixed solution into the shell layer syringe of the coaxial electrospinning device, adding the third mixed solution into the core layer syringe of the coaxial electrospinning device, and performing coaxial electrospinning to obtain the spinning membrane;

[0013] The conditions for coaxial electrospinning include: the injection speed of the shell layer syringe is 0.06mm / min~0.1mm / min, the injection speed of the core layer syringe is 0.03mm / min~0.08mm / min, the spinning receiving drum speed is 70r / min~90r / min, the spinning stroke is 20cm~50cm, the coaxial electrospinning time is 7 hours~8 hours, and the spinning voltage is 14kV~16kV.

[0014] Optionally, the volume ratio of the second mixed solution to the third mixed solution is (3-6):5.

[0015] Optionally, the mass concentration of the polyethylene glycol in the third mixed solution is 6% g / ml to 8% g / ml.

[0016] Optionally, adding the second mixed solution into an electrospinning device for electrospinning to obtain a spinning membrane comprises:

[0017] adding the second mixed solution into a syringe in a non-coaxial electrospinning device to perform non-coaxial electrospinning to obtain the spinning membrane;

[0018] The conditions for non-coaxial electrospinning include: the injection speed of the syringe is 0.06 mm / min to 0.1 mm / min, the rotation speed of the spinning receiving drum is 70 r / min to 90 r / min, the spinning stroke is 20 cm to 50 cm, the non-coaxial electrospinning time is 7 hours to 8 hours, and the spinning voltage is 14 kV to 16 kV.

[0019] Optionally, the dipolar aprotic solvent is at least one of N,N-dimethylformamide, N-methylpyrrolidone, and N,N-dimethylacetamide.

[0020] Optionally, the polyurethane material is at least one of thermoplastic polyurethane elastomer and polyurethane elastomer.

[0021] Optionally, the piezoelectric polymer is at least one of polyvinylidene fluoride-trifluoroethylene, polyvinylidene fluoride, and polylactic acid.

[0022] Optionally, the step of sequentially drying, soaking, cleaning, and drying the spun membrane to obtain a piezoelectric fiber membrane includes:

[0023] drying the spinning membrane at a second preset temperature and for a second preset time to obtain a dried spinning membrane;

[0024] soaking the dried spinning membrane in anhydrous ethanol for a third preset time to obtain a soaked spinning membrane;

[0025] cleaning the soaked spinning membrane for a fourth preset time period to obtain a cleaned spinning membrane;

[0026] drying the cleaned spinning membrane at the second preset temperature for the second preset time to obtain the piezoelectric fiber membrane;

[0027] The second preset temperature is 60°C to 80°C; the second preset time is 12 hours to 14 hours, the third preset time is 12 hours to 15 hours, and the fourth preset time is 1 hour to 1.5 hours.

[0028] According to another aspect of the disclosed embodiments of the present invention, a piezoelectric fiber membrane is provided. The piezoelectric fiber membrane is prepared by any of the methods described above.

[0029] According to another aspect of the disclosed embodiments of the present invention, there is provided an application of a piezoelectric fiber membrane, wherein the piezoelectric fiber membrane is used as a filter membrane of a filter element, and the piezoelectric fiber membrane is prepared by any of the methods described above.

[0030] The method for preparing the piezoelectric fiber membrane provided by the present invention has the following technical effects:

[0031] The present invention adds polyethylene glycol to a dipolar aprotic solvent and stirs until the polyethylene glycol is completely dissolved to obtain a first mixed solution; adds a polyurethane material and a piezoelectric polymer to the first mixed solution in sequence, and stirs for a first preset time at a first preset temperature to obtain a second mixed solution, wherein the mass ratio of the polyethylene glycol, the polyurethane material and the piezoelectric polymer is (0.5-1):(0.5-1):(8-9), the volume ratio of the mass of the polyethylene glycol to the dipolar aprotic solvent, and the volume ratio of the mass of the polyurethane material to the dipolar aprotic solvent are 0.0 06g / ml~0.012g / ml, the volume ratio of the mass of the piezoelectric polymer to the dipolar aprotic solvent is 0.096g / ml~0.108g / ml; the second mixed solution is added into an electrospinning device for electrospinning to obtain a spinning membrane; the spinning membrane is dried, soaked, cleaned and dried in sequence to obtain a piezoelectric fiber membrane, so that the prepared piezoelectric fiber membrane has good piezoelectric properties and enhanced guiding effect on piezoelectric charges, so that it can be used as a filter membrane to improve the scale inhibition effect, and has a stable structure and good durability. At the same time, it is green and environmentally friendly, reducing pollution to the environment.

[0032] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 is a schematic flow chart of a method for preparing a piezoelectric fiber membrane according to an exemplary embodiment;

[0035] Figure 2 is a scanning electron microscope image of micro-nano pores according to an exemplary embodiment;

[0036] Figure 3 is a scanning electron microscope image of a piezoelectric fiber membrane prepared by a non-coaxial electrospinning method according to an exemplary embodiment;

[0037] Figure 4 The figure is a scanning electron microscope image of a piezoelectric fiber membrane prepared by coaxial electrospinning according to an exemplary embodiment. DETAILED DESCRIPTION

[0038] In order to enable ordinary persons in the art to better understand the technical solutions disclosed in the present invention, the technical solutions in the embodiments disclosed in the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without making any creative work shall fall within the scope of protection of the present invention.

[0039] It should be noted that the terms "first", "second", etc. in the specification and claims disclosed in the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0040] For the purpose of the following detailed description, it should be understood that the present invention may adopt various alternative variations and step sequences, unless expressly provided otherwise. In addition, except in any operating examples, or when otherwise indicated, all numerals representing the amount of the components used in the specification and claims should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters set forth in the following specification and the appended claims are approximate values ​​that vary according to the desired performance to be obtained by the present invention. At least, it is not intended to limit the application of the doctrine of equivalents to the scope of the claims, and each numerical parameter should at least be interpreted according to the number of reported significant figures and by applying ordinary rounding techniques.

[0041] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0042] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be merged. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein. For example, a specified range from "1 to 10" should be considered to include any and all subranges between a minimum of 1 and a maximum of 10. Exemplary subranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, etc.

[0043] Nanofiltration filters, widely used in household water treatment, are the primary filter element in water purifiers. Made primarily of polymer materials, they are quite expensive due to the complex production process. With use, scale gradually forms on the membrane surface, blocking the pores and rapidly reducing membrane flux, leading to loss of separation performance. Scale is a poorly or slightly soluble salt with exceptional solubility, easily depositing on the walls of containers, particularly metal surfaces. Scale is typically white or off-white, hard, and dense, and is primarily composed of carbonates, sulfates, and calcium phosphates.

[0044] Common anti-scaling methods are mainly divided into physical and chemical methods, and their principle is to inhibit or eliminate scale. Chemical methods mainly use scale inhibitors to prevent scale from forming or adhering to the surface of the filter membrane, thereby extending the service life of the membrane. Physical methods mainly use electrical, magnetic, optical, acoustic and other technical scale prevention or descaling methods to prevent scaling substances from adhering to the wall or crystallizing and growing on the wall of the heating tube. Typical examples include ultrasonic descaling technology, which mainly uses ultrasonic waves to change the distance between liquid molecules, reduce molecular cohesion, and at the same time create cavities in the liquid. The rupture generates pressure and shatters the precipitated scale crystals into fine particles that can easily flow away with the water.

[0045] At present, chemical scale prevention and descaling methods are more commonly used. Their actual operation is simple, time-saving and labor-saving, but most water treatment agents are phosphorus-based, and the problem of eutrophication of water bodies is prominent, which can easily cause secondary pollution of drinking water. The physical ultrasonic descaling method has complex equipment and high cost, and is not suitable for household water purification devices. Therefore, the present application provides a method for preparing a piezoelectric fiber membrane. The piezoelectric fiber membrane prepared by this method has good piezoelectric properties, enhanced guiding effect on piezoelectric charges, and can be used as a filter membrane of a filter element, thereby improving the scale prevention effect, and has a stable structure and good durability. At the same time, it is green and environmentally friendly, reducing pollution to the environment.

[0046] See also Figure 1 , Figure 1It is a flow chart of a method for preparing a piezoelectric fiber membrane according to an exemplary embodiment. This specification provides the method operation steps as described in the embodiment or flow chart, but may include more or fewer operation steps based on conventional or non-creative labor. The order of steps listed in the embodiment is only one way of executing the steps among many steps, and does not represent the only execution order. When the actual system or server product is executed, it can be executed in sequence or in parallel (for example, in a parallel processor or multi-threaded processing environment) according to the method shown in the embodiment or the accompanying drawings. Specifically, Figure 1 As shown, the above method may include:

[0047] S101: adding polyethylene glycol to a dipolar aprotic solvent and stirring until the polyethylene glycol is completely dissolved to obtain a first mixed solution;

[0048] S103: adding the polyurethane material and the piezoelectric polymer to the first mixed solution in sequence, and stirring at a first preset temperature for a first preset time to obtain a second mixed solution;

[0049] S105: adding the second mixed solution into an electrospinning device for electrospinning to obtain a spinning membrane;

[0050] S107: drying, soaking, cleaning and drying the spun membrane in sequence to obtain a piezoelectric fiber membrane.

[0051] In one embodiment, the dipolar aprotic solvent is at least one of N,N-dimethylformamide, N-methylpyrrolidone, and N,N-dimethylacetamide. The molecular weight of the polyethylene glycol powder is 200 to 4000. In practical applications, polyethylene glycol with a larger molecular weight (e.g., 4000) is generally selected for ease of dissolution.

[0052] Alternatively, polyethylene glycol may be added to a dipolar aprotic solvent and stirred at a temperature ranging from 40°C to 50°C (excluding 50°C) until the polyethylene glycol is completely dissolved to form a transparent, clear solution. Alternatively, polyethylene glycol may be added to a mixed solution of the dipolar aprotic solvent and acetone and stirred until the polyethylene glycol is completely dissolved to form a transparent, clear solution, wherein the volume ratio of the dipolar aprotic solvent to the acetone solution is 3:2 to 1:1. It is understood that the temperature may be any value between 40°C and 50°C (excluding 50°C), such as 40°C, 42°C, 44°C, 46°C, 48°C, etc., which are not enumerated here; and the volume ratio of the dipolar aprotic solvent to the acetone solution may be any ratio between 3:2 and 1:1, such as 3:2, 2.5:1.5, 1:1, etc., which are not enumerated here.

[0053] In a specific embodiment, the polyurethane material is at least one of thermoplastic polyurethane elastomer and polyurethane elastomer, and the piezoelectric polymer is at least one of polyvinylidene fluoride-trifluoroethylene, polyvinylidene fluoride, and polylactic acid. The second mixed solution is a white uniform viscous mixed solution.

[0054] Optionally, the mass ratio of polyethylene glycol, polyurethane material, and piezoelectric polymer is (0.5-1):(0.5-1):(8-9), the volume ratio of the polyethylene glycol mass to the dipolar aprotic solvent, and the volume ratio of the polyurethane material mass to the dipolar aprotic solvent are 0.006 g / ml to 0.012 g / ml, and the volume ratio of the piezoelectric polymer mass to the dipolar aprotic solvent is 0.096 g / ml to 0.108 g / ml. The first preset temperature is 35°C to 45°C, and the first preset time is more than 3 hours. The specific setting of the first preset time is determined by the actual state of the second mixed solution. It can be understood that the mass ratio of the above-mentioned polyethylene glycol to the volume ratio of the dipolar aprotic solvent, and the volume ratio of the mass of the polyurethane material to the dipolar aprotic solvent can be any point value between 0.006g / ml and 0.012g / ml, such as 0.006g / ml, 0.007g / ml, 0.008g / ml, 0.009g / ml, 0.010g / ml, 0.011g / ml, 0.012g / ml, etc., which are not enumerated here; the mass ratio of the above-mentioned piezoelectric polymer to the volume ratio of the dipolar aprotic solvent can be any point value between 0.096g / ml and 0.108g / ml, such as 0.096g / ml, 0.098g / ml, 0.100g / ml, 0.102g / ml, 0.104g / ml, 0.106g / ml, 0.108g / ml, etc., which are not enumerated here.

[0055] In a specific embodiment, the electrospinning device may include a coaxial electrospinning device and a non-coaxial electrospinning device. After obtaining the second mixed solution, the solution may be placed in a syringe for defoaming and then mounted on the electrospinning device.

[0056] Optionally, the above step S105 may include:

[0057] The second mixed solution is added into a syringe in a non-coaxial electrospinning device for non-coaxial electrospinning to obtain a spinning membrane.

[0058] In one embodiment, the non-coaxial electrospinning conditions include: an injection speed of 0.06 mm / min to 0.1 mm / min, a spinning drum rotation speed of 70 rpm to 90 rpm, a spinning stroke of 20 cm to 50 cm, a non-coaxial electrospinning time of 7 to 8 hours, and a spinning voltage of 14 kV to 16 kV. The spinning drum is provided with a flat aluminum foil coating.

[0059] In practical applications, the parameters of the syringe injection speed, spinning drum speed, and spinning voltage are usually fixed, and the thickness of the resulting spun film is controlled by adjusting the spinning time or spinning stroke. Specifically, when the parameters of the syringe injection speed, spinning drum speed, spinning voltage, and spinning stroke are fixed, the longer the spinning time, the thicker the resulting spun film; when the parameters of the syringe injection speed, spinning drum speed, spinning voltage, and spinning time are fixed, the longer the spinning stroke, the thinner the resulting spun film. The thickness of the fiber film can be controlled during the preparation process. The thickness of the spun film produced is usually 300μm to 500μm.

[0060] In an optional embodiment, before step S105, the method may further include:

[0061] Polyethylene glycol is added to the ethanol solution and stirred until the polyethylene glycol is completely dissolved to obtain a third mixed solution.

[0062] Accordingly, the above step S105 may further include:

[0063] The second mixed solution is added into the shell layer syringe of the coaxial electrospinning device, and the third mixed solution is added into the core layer syringe of the coaxial electrospinning device, and coaxial electrospinning is performed to obtain a spinning membrane.

[0064] Optionally, the mass concentration of polyethylene glycol in the third mixed solution is 6% g / ml to 8% g / ml, and the volume ratio of the second mixed solution to the third mixed solution is (3-6):5. The molecular weight of the polyethylene glycol powder is 200-4000. It can be understood that the mass concentration of polyethylene glycol in the third mixed solution can be any point value between 6% g / ml and 8% g / ml, such as 6% g / ml, 6.5% g / ml, 7% g / ml, 7.5% g / ml, 8% g / ml, etc., which are not enumerated here; the volume ratio of the second mixed solution to the third mixed solution can be any ratio between (3-6):5, such as 3:5, 4:5, 1:1, 6:5, etc., which are not enumerated here.

[0065] In a specific embodiment, the conditions for the coaxial electrospinning include: the injection speed of the shell layer syringe is 0.06mm / min to 0.1mm / min, the injection speed of the core layer syringe is 0.03mm / min to 0.08mm / min, the spinning receiving drum speed is 70r / min to 90r / min, the spinning stroke is 20cm to 50cm, the coaxial electrospinning time is 7 hours to 8 hours, and the spinning voltage is 14kV to 16kV. Specifically, the thickness control during the coaxial electrospinning process is the same as that of the non-coaxial electrospinning method described above, and will not be repeated here.

[0066] In an optional embodiment, the above step S107 may include:

[0067] drying the spinning membrane at a second preset temperature for a second preset time to obtain a dried spinning membrane;

[0068] soaking the dried spinning membrane in anhydrous ethanol for a third preset time to obtain a soaked spinning membrane;

[0069] cleaning the soaked spinning membrane for a fourth preset time period to obtain a cleaned spinning membrane;

[0070] The cleaned spinning membrane is dried at a second preset temperature for a second preset time to obtain a piezoelectric fiber membrane.

[0071] In a specific embodiment, the second preset temperature is 60°C to 80°C, the second preset time is 12 hours to 14 hours, the third preset time is 12 hours to 15 hours, and the fourth preset time is 1 hour to 1.5 hours.

[0072] In practical applications, the aluminum foil and the spinning membrane on it are placed in a vacuum drying oven for drying to remove the residual solution in the membrane. The spinning membrane is then peeled off from the aluminum foil, soaked in anhydrous ethanol for a certain period of time, and then ultrasonically cleaned to remove the polyethylene glycol in the fiber. The membrane is then placed in a vacuum drying oven again for drying to obtain the above-mentioned piezoelectric fiber membrane.

[0073] In the embodiment of this specification, after soaking in anhydrous ethanol, the polyethylene glycol present in the fiber can be removed, so that the fiber membrane surface has micro-nano pores (such as Figure 2 Based on the above non-coaxial electrospinning method, a piezoelectric nanofiber membrane with dense micro-nano pores on the tube wall can be obtained (as shown in Figure 3 As shown), in the above-mentioned coaxial electrospinning method, since the third mixed solution in the core layer syringe of the coaxial electrospinning device contains polyethylene glycol, the polyethylene glycol will be removed during the soaking and cleaning process of the spinning membrane, thereby obtaining a fiber membrane with a hollow interior and dense micro-nano pores on the tube wall (as shown). Figure 4As shown), its piezoelectric properties are further enhanced, thereby enhancing its anti-scaling effect as a water purifier filter membrane.

[0074] After piezoelectric performance experimental testing, the piezoelectric nanofiber membrane prepared by the above method can generate an open circuit voltage of about 160V to 220V under a low-frequency impact of 55N pressure per square centimeter, while the fiber membrane prepared by the traditional method can generate an open circuit voltage of about 130V. The piezoelectric nanofiber membrane prepared according to the preparation method provided in this application has good piezoelectric properties.

[0075] The preparation method of this application features a simple process, mild conditions, and easy control. The raw materials used are all non-toxic or low-toxic, resulting in low raw material consumption and low cost. No toxic byproducts are generated, making it an environmentally friendly synthesis method. The resulting piezoelectric nanofiber membrane maintains excellent morphology and strength, and has broad application prospects in functional textiles, water and air purification, and chemical separation and extraction.

[0076] The present application also provides a piezoelectric fiber membrane, which is prepared using the above-mentioned preparation method.

[0077] The present application also provides an application of the piezoelectric fiber membrane as described above, wherein the piezoelectric fiber membrane is used as a filter membrane of a filter element. The piezoelectric fiber membrane is prepared by the above-mentioned preparation method, wherein the filter element can be a filter element of a water purification device.

[0078] In the embodiments of this specification, a piezoelectric nanofiber membrane can be directly wrapped around the outside of a nanofiltration filter element and installed on the entire machine to detect whether a piezoelectric field is generated. When the water purifier is operating normally, the pressure inside and outside the filter element is between 0.5MPa and 0.6MPa, or approximately 50N to 60N per square centimeter. Testing has shown that the fiber membrane produced using the above preparation method can generate an open-circuit voltage of approximately 120V to 135V under this internal and external water pressure differential. This provides good scale inhibition while preventing the precipitation of mineral ions in the water, and is relatively low in cost.

[0079] In practical applications, the filter element can be installed on the drum of the electrospinning machine as a spinning receiving drum, and the piezoelectric nanofiber membrane can be directly spun onto the nanofiltration filter element to obtain an integrated composite nanofiltration filter element. Since most heavy metal ions in water are positively charged ions, scale is mostly produced by divalent ions such as calcium and magnesium. During the use of the nanofiltration filter element with the above-mentioned piezoelectric nanofiber membrane, since the fiber membrane has good piezoelectric properties, when the fiber membrane is subjected to external force, the internal dipole is deformed, generating a piezoelectric field with one side positive and the other side negative. This allows the positive ions to be affected by the electric field force and migrate from the inside of the filter element (i.e., the purified water end) to the outside (i.e., the raw water end), thereby greatly reducing the adhesion of the ions on the filter element membrane layer, preventing the ions in the water from crystallizing on the surface of the filter membrane and causing the membrane pores to be blocked, thereby achieving a natural scale inhibition effect. At the same time, when the water purifier stops working, the piezoelectric field generated by the pressure difference of the fiber membrane will disappear, and no additional loss will be caused to the filter element, thus protecting the life of the filter element structure.

[0080] The following describes a specific embodiment of the present application in conjunction with the above-mentioned method for preparing the piezoelectric fiber membrane.

[0081] Example 1

[0082] Step 1: Add 0.5 parts of polyethylene glycol to N,N-dimethylformamide and stir until the polyethylene glycol is completely dissolved, then add 0.5 parts of thermoplastic polyurethane elastomer and 9 parts of polyvinylidene fluoride-trifluoroethylene in sequence, and stir at 35°C for 5 hours to obtain a second mixed solution, wherein the ratio of the mass of polyethylene glycol to the volume of N,N-dimethylformamide is 0.006 g / ml, the ratio of the mass of thermoplastic polyurethane elastomer to the volume of N,N-dimethylformamide is 0.006 g / ml, and the ratio of the mass of polyvinylidene fluoride-trifluoroethylene to the volume of N,N-dimethylformamide is 0.108 g / ml.

[0083] Step 2: Add the second mixed solution after standing and defoaming into the syringe in the non-coaxial electrospinning device for non-coaxial electrospinning to obtain a spinning membrane, wherein the injection speed of the syringe is 0.06 mm / min, the rotation speed of the spinning receiving drum is 70 r / min, the spinning stroke is 20 cm, the non-coaxial electrospinning time is 8 hours, the spinning voltage is 14 kV, and the spinning receiving drum is provided with a flat aluminum foil.

[0084] Step 3: Place the spinning membrane in a vacuum drying oven and dry it at 60°C for 14 hours. Peel the dried spinning membrane off the aluminum foil, soak it in anhydrous ethanol for 14 hours, and then ultrasonically clean it for 2 hours. Then, place the cleaned spinning membrane in a vacuum drying oven again and dry it at 60°C for 14 hours to obtain a piezoelectric nanofiber membrane with dense micro-nano pores on the tube wall and a thickness of 500 μm.

[0085] Example 2

[0086] Step 1: Add 1 part of polyethylene glycol to N,N-dimethylformamide and stir until the polyethylene glycol is completely dissolved, then add 1 part of thermoplastic polyurethane elastomer and 8 parts of polyvinylidene fluoride-trifluoroethylene in sequence, and stir at 40°C for 4 hours to obtain a second mixed solution, wherein the ratio of the mass of polyethylene glycol to the volume of N,N-dimethylformamide is 0.012 g / ml, the ratio of the mass of thermoplastic polyurethane elastomer to the volume of N,N-dimethylformamide is 0.012 g / ml, and the ratio of the mass of polyvinylidene fluoride-trifluoroethylene to the volume of N,N-dimethylformamide is 0.096 g / ml.

[0087] Step 2: Add the second mixed solution after standing and defoaming into the syringe in the non-coaxial electrospinning device for non-coaxial electrospinning to obtain a spinning membrane, wherein the injection speed of the syringe is 0.08 mm / min, the rotation speed of the spinning receiving drum is 80 r / min, the spinning stroke is 50 cm, the non-coaxial electrospinning time is 7 hours, the spinning voltage is 15 kV, and the spinning receiving drum is provided with a flat aluminum foil.

[0088] Step 3: Place the spinning membrane in a vacuum drying oven and dry it at 70°C for 13 hours. Peel the dried spinning membrane off the aluminum foil, soak it in anhydrous ethanol for 13 hours, and then ultrasonically clean it for 1.5 hours. Then, place the cleaned spinning membrane in a vacuum drying oven again and dry it at 70°C for 13 hours to obtain a piezoelectric nanofiber membrane with dense micro-nano pores on the tube wall and a thickness of 300 μm.

[0089] Example 3

[0090] Step 1: Add 0.75 parts of polyethylene glycol to N,N-dimethylformamide and stir until the polyethylene glycol is completely dissolved, then add 0.75 parts of thermoplastic polyurethane elastomer and 8.5 parts of polyvinylidene fluoride-trifluoroethylene in sequence, and stir at 45°C for 3 hours to obtain a second mixed solution, wherein the ratio of the mass of polyethylene glycol to the volume of N,N-dimethylformamide is 0.009 g / ml, the ratio of the mass of thermoplastic polyurethane elastomer to the volume of N,N-dimethylformamide is 0.009 g / ml, and the ratio of the mass of polyvinylidene fluoride-trifluoroethylene to the volume of N,N-dimethylformamide is 0.102 g / ml.

[0091] Step 2: Add the second mixed solution after standing and defoaming into the syringe in the non-coaxial electrospinning device for non-coaxial electrospinning to obtain a spinning membrane, wherein the injection speed of the syringe is 0.1 mm / min, the rotation speed of the spinning receiving drum is 90 r / min, the spinning stroke is 40 cm, the non-coaxial electrospinning time is 7.5 hours, the spinning voltage is 16 kV, and the spinning receiving drum is provided with a flat aluminum foil.

[0092] Step 3: Place the spinning membrane in a vacuum drying oven and dry it at 80°C for 12 hours. Peel the dried spinning membrane off the aluminum foil, soak it in anhydrous ethanol for 12 hours, and then ultrasonically clean it for 1 hour. Then, place the cleaned spinning membrane in a vacuum drying oven again and dry it at 80°C for 12 hours to obtain a piezoelectric nanofiber membrane with dense micro-nano pores on the tube wall and a thickness of 400 μm.

[0093] Example 4

[0094] Step 1: Add 0.5 parts of polyethylene glycol to a mixed solution of N,N-dimethylformamide and acetone solution and stir until the polyethylene glycol is completely dissolved, then add 0.5 parts of thermoplastic polyurethane elastomer and 9 parts of polyvinylidene fluoride-trifluoroethylene in sequence, and stir at 35°C for 5 hours to obtain a second mixed solution, wherein the volume ratio of N,N-dimethylformamide and acetone solution is 3:2, the ratio of the mass of polyethylene glycol to the volume of the mixed solution of N,N-dimethylformamide and acetone solution is 0.006 g / ml, the ratio of the mass of thermoplastic polyurethane elastomer to the volume of the mixed solution of N,N-dimethylformamide and acetone solution is 0.006 g / ml, and the ratio of the mass of polyvinylidene fluoride-trifluoroethylene to the volume of the mixed solution of N,N-dimethylformamide and acetone solution is 0.108 g / ml.

[0095] Step 2: Add polyethylene glycol to the ethanol solution and stir until the polyethylene glycol is completely dissolved to obtain a third mixed solution. The mass concentration of polyethylene glycol in the third mixed solution is 6% g / ml, and the volume ratio of the second mixed solution to the third mixed solution is 3:5.

[0096] Step 3: Add the second mixed solution after standing and defoaming to the shell layer syringe of the coaxial electrospinning device, and add the third mixed solution to the core layer syringe of the coaxial electrospinning device to perform coaxial electrospinning to obtain a spinning membrane, wherein the injection speed of the shell layer syringe is 0.06 mm / min, the injection speed of the core layer syringe is 0.03 mm / min, the rotation speed of the spinning receiving drum is 70 r / min, the spinning stroke is 20 cm, the non-coaxial electrospinning time is 8 hours, the spinning voltage is 14 kV, and the spinning receiving drum is provided with a flat aluminum foil.

[0097] Step 4: Place the spinning membrane in a vacuum drying oven and dry it at 60°C for 14 hours. Peel the dried spinning membrane off the aluminum foil, soak it in anhydrous ethanol for 14 hours, and then ultrasonically clean it for 2 hours. Then, place the cleaned spinning membrane in a vacuum drying oven again and dry it at 60°C for 14 hours to obtain a piezoelectric nanofiber membrane with a hollow interior, densely covered micro-nanopores on the tube wall and a thickness of 500μm.

[0098] Example 5

[0099] Step 1: Add 1 part of polyethylene glycol to a mixed solution of N,N-dimethylformamide and acetone solution and stir until the polyethylene glycol is completely dissolved, then add 1 part of thermoplastic polyurethane elastomer and 8 parts of polyvinylidene fluoride-trifluoroethylene in sequence, and stir at 40°C for 4 hours to obtain a second mixed solution, wherein the volume ratio of N,N-dimethylformamide and acetone solution is 1:1, the ratio of the mass of polyethylene glycol to the volume of the mixed solution of N,N-dimethylformamide and acetone solution is 0.012 g / ml, the ratio of the mass of thermoplastic polyurethane elastomer to the volume of the mixed solution of N,N-dimethylformamide and acetone solution is 0.012 g / ml, and the ratio of the mass of polyvinylidene fluoride-trifluoroethylene to the volume of the mixed solution of N,N-dimethylformamide and acetone solution is 0.096 g / ml.

[0100] Step 2: Add polyethylene glycol to the ethanol solution and stir until the polyethylene glycol is completely dissolved to obtain a third mixed solution. The mass concentration of polyethylene glycol in the third mixed solution is 7% g / ml, and the volume ratio of the second mixed solution to the third mixed solution is 4.5:5.

[0101] Step 3: Add the second mixed solution after standing and defoaming to the shell layer syringe of the coaxial electrospinning device, and add the third mixed solution to the core layer syringe of the coaxial electrospinning device to perform coaxial electrospinning to obtain a spinning membrane, wherein the injection speed of the shell layer syringe is 0.08 mm / min, the injection speed of the core layer syringe is 0.04 mm / min, the rotation speed of the spinning receiving drum is 80 r / min, the spinning stroke is 50 cm, the non-coaxial electrospinning time is 7 hours, the spinning voltage is 15 kV, and the spinning receiving drum is provided with a flat aluminum foil.

[0102] Step 4: Place the spinning membrane in a vacuum drying oven and dry it at 70°C for 13 hours. Peel the dried spinning membrane off the aluminum foil, soak it in anhydrous ethanol for 13 hours, and then ultrasonically clean it for 1.5 hours. Then, place the cleaned spinning membrane in a vacuum drying oven again and dry it at 70°C for 13 hours to obtain a piezoelectric nanofiber membrane with a hollow interior, densely covered micro-nanopores on the tube wall and a thickness of 300μm.

[0103] Example 6

[0104] Step 1: Add 0.75 parts of polyethylene glycol to a mixed solution of N,N-dimethylformamide and acetone solution and stir until the polyethylene glycol is completely dissolved, then add 0.75 parts of thermoplastic polyurethane elastomer and 8.5 parts of polyvinylidene fluoride-trifluoroethylene in sequence, and stir at 45°C for 3 hours to obtain a second mixed solution, wherein the volume ratio of N,N-dimethylformamide and acetone solution is 2:1.5, the ratio of the mass of polyethylene glycol to the volume of the mixed solution of N,N-dimethylformamide and acetone solution is 0.009 g / ml, the ratio of the mass of thermoplastic polyurethane elastomer to the volume of the mixed solution of N,N-dimethylformamide and acetone solution is 0.009 g / ml, and the ratio of the mass of polyvinylidene fluoride-trifluoroethylene to the volume of the mixed solution of N,N-dimethylformamide and acetone solution is 0.102 g / ml.

[0105] Step 2: Add polyethylene glycol to the ethanol solution and stir until the polyethylene glycol is completely dissolved to obtain a third mixed solution. The mass concentration of polyethylene glycol in the third mixed solution is 8% g / ml, and the volume ratio of the second mixed solution to the third mixed solution is 6:5.

[0106] Step 3: Add the second mixed solution after standing and defoaming to the shell layer syringe of the coaxial electrospinning device, and add the third mixed solution to the core layer syringe of the coaxial electrospinning device to perform coaxial electrospinning to obtain a spinning membrane, wherein the injection speed of the shell layer syringe is 0.1 mm / min, the injection speed of the core layer syringe is 0.08 mm / min, the rotation speed of the spinning receiving drum is 90 r / min, the spinning stroke is 40 cm, the non-coaxial electrospinning time is 7.5 hours, the spinning voltage is 16 kV, and the spinning receiving drum is provided with a flat aluminum foil.

[0107] Step 4: Place the spinning membrane in a vacuum drying oven and dry it at 80°C for 12 hours. Peel the dried spinning membrane off the aluminum foil, soak it in anhydrous ethanol for 12 hours, and then ultrasonically clean it for 1 hour. Then, place the cleaned spinning membrane in a vacuum drying oven again and dry it at 80°C for 12 hours to obtain a piezoelectric nanofiber membrane with a hollow interior, densely covered micro-nanopores on the tube wall and a thickness of 400μm.

[0108] In summary, the piezoelectric fiber membrane prepared in this application has good piezoelectric properties and can enhance the guiding effect of piezoelectric charges, thereby improving the scale inhibition effect when used as a filter membrane. It also has a stable structure and good durability. It is also environmentally friendly and reduces environmental pollution. The method for preparing the piezoelectric fiber membrane is simple, the conditions are mild, and it is easy to control. The reaction process consumes little raw materials and is low in cost.

[0109] The above disclosures are merely some preferred embodiments of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a piezoelectric fiber membrane, characterized in that: include: adding polyethylene glycol to a dipolar aprotic solvent and stirring until the polyethylene glycol is completely dissolved to obtain a first mixed solution; adding a polyurethane material and a piezoelectric polymer to the first mixed solution in sequence, and stirring at a first preset temperature for a first preset time to obtain a second mixed solution; wherein the mass ratio of the polyethylene glycol, the polyurethane material, and the piezoelectric polymer is (0.5-1):(0.5-1):(8-9), the volume ratio of the mass of the polyethylene glycol to the dipolar aprotic solvent, and the volume ratio of the mass of the polyurethane material to the dipolar aprotic solvent are 0.006 g / ml to 0.012 g / ml, and the volume ratio of the mass of the piezoelectric polymer to the dipolar aprotic solvent is 0.096 g / ml to 0.108 g / ml; adding the second mixed solution into an electrospinning device for electrospinning to obtain a spinning membrane; The spinning membrane is sequentially dried, soaked, cleaned and dried to obtain a piezoelectric fiber membrane.

2. The method according to claim 1, characterized in that The electrospinning device includes a coaxial electrospinning device. Before adding the second mixed solution to the electrospinning device for electrospinning to obtain a spinning membrane, the method further includes: adding polyethylene glycol to the ethanol solution and stirring until the polyethylene glycol is completely dissolved to obtain a third mixed solution; The step of adding the second mixed solution into an electrospinning device for electrospinning to obtain a spinning membrane comprises: adding the second mixed solution into the shell layer syringe of the coaxial electrospinning device, adding the third mixed solution into the core layer syringe of the coaxial electrospinning device, and performing coaxial electrospinning to obtain the spinning membrane; The conditions for coaxial electrospinning include: the injection speed of the shell layer syringe is 0.06mm / min~0.1mm / min, the injection speed of the core layer syringe is 0.03mm / min~0.08mm / min, the spinning receiving drum speed is 70r / min~90r / min, the spinning stroke is 20cm~50cm, the coaxial electrospinning time is 7 hours~8 hours, and the spinning voltage is 14kV~16kV.

3. The method according to claim 2, characterized in that The volume ratio of the second mixed solution to the third mixed solution is (3-6):

5.

4. The method according to claim 2, characterized in that The mass concentration of the polyethylene glycol in the third mixed solution is 6% g / ml to 8% g / ml.

5. The method according to claim 1, wherein The step of adding the second mixed solution into an electrospinning device for electrospinning to obtain a spinning membrane comprises: adding the second mixed solution into a syringe in a non-coaxial electrospinning device to perform non-coaxial electrospinning to obtain the spinning membrane; The conditions for non-coaxial electrospinning include: the injection speed of the syringe is 0.06 mm / min to 0.1 mm / min, the rotation speed of the spinning receiving drum is 70 r / min to 90 r / min, the spinning stroke is 20 cm to 50 cm, the non-coaxial electrospinning time is 7 hours to 8 hours, and the spinning voltage is 14 kV to 16 kV.

6. The method according to claim 1, characterized in that The dipolar aprotic solvent is at least one of N,N-dimethylformamide, N-methylpyrrolidone, and N,N-dimethylacetamide.

7. The method according to claim 1, characterized in that The polyurethane material is at least one of thermoplastic polyurethane elastomer and polyurethane elastomer.

8. The method according to claim 1, characterized in that The piezoelectric polymer is at least one of polyvinylidene fluoride-trifluoroethylene, polyvinylidene fluoride, and polylactic acid.

9. The method according to claim 1, characterized in that The step of sequentially drying, soaking, cleaning, and drying the spun membrane to obtain a piezoelectric fiber membrane comprises: drying the spinning membrane at a second preset temperature and for a second preset time to obtain a dried spinning membrane; soaking the dried spinning membrane in anhydrous ethanol for a third preset time to obtain a soaked spinning membrane; cleaning the soaked spinning membrane for a fourth preset time period to obtain a cleaned spinning membrane; drying the cleaned spinning membrane at the second preset temperature for the second preset time to obtain the piezoelectric fiber membrane; The second preset temperature is 60°C to 80°C; the second preset time is 12 hours to 14 hours, the third preset time is 12 hours to 15 hours, and the fourth preset time is 1 hour to 1.5 hours.

10. A piezoelectric fiber membrane, characterized in that: The piezoelectric fiber membrane is prepared by the method according to any one of claims 1 to 9.

11. An application of a piezoelectric fiber membrane, characterized in that: The piezoelectric fiber membrane is used as a filter membrane of a filter element, and the piezoelectric fiber membrane is prepared by the method described in any one of claims 1 to 9.

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