Crosslinked polyvinyl alcohol composite spinning membrane and preparation method thereof
The polyvinyl alcohol spinning membrane was prepared by electrospinning and composited with perfluorosulfonic acid, which solved the problem of poor barrier properties of the proton exchange membrane and improved the performance of the fuel cell.
Patent Information
- Application Number
- CN202510711248.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-10-17
AI Technical Summary
Existing proton exchange membranes have poor barrier properties, high fuel permeability, and large water swelling, which cannot fully exert the performance advantages of fuel cells.
The polyvinyl alcohol spinning membrane was prepared by electrospinning, and then modified by glutaraldehyde cross-linking and compounded with perfluorosulfonic acid to form a cross-linked polyvinyl alcohol composite spinning membrane, which enhanced the proton conductivity and anti-swelling property of the membrane.
The water resistance and swelling resistance of the proton exchange membrane are improved, the proton conductivity and mechanical strength of the membrane are increased, and the overall performance of the fuel cell is enhanced.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of proton exchange membranes, and in particular to a cross-linked polyvinyl alcohol composite spinning membrane and a preparation method thereof. Background Art
[0002] Energy is an important material basis for the existence and development of human society. Every improvement and change in energy has promoted the progress of society. At present, traditional fossil fuels such as coal and oil still occupy a major position in my country's energy structure. The combustion process of fossil fuels is accompanied by the emission of a large amount of pollutants such as SO2 and CO2, which leads to environmental pollution and greenhouse effect. Fuel cells can directly convert the chemical energy stored in the fuel into electrical energy. It is not restricted by the Carnot cycle effect and has the advantage of high energy conversion efficiency. In addition, fuel cells also have the advantages of strong modularity and green environmental protection, so they have received widespread attention in recent years. Proton exchange membrane is one of the core components of fuel cells. It is mainly responsible for providing channels for the migration and transport of protons and blocking fuel. Although the currently used perfluorosulfonic acid proton exchange membrane ( Nafion ) have good oxidative stability. However, they have poor fuel barrier properties, high fuel permeability, and significant water swelling, preventing them from fully realizing the performance advantages of fuel cells. Consequently, increasing research is being devoted to the development of fluorinated or non-fluorinated proton exchange membranes. Summary of the Invention
[0003] The present invention provides a cross-linked polyvinyl alcohol composite spinning membrane and a preparation method thereof, which solves the problem of poor barrier properties of proton exchange membranes in related technologies.
[0004] The technical solutions of the present invention are as follows: The present invention provides a method for preparing a cross-linked polyvinyl alcohol composite spinning membrane, comprising the following steps: S1, taking polyvinyl alcohol spinning solution and performing electrospinning to obtain polyvinyl alcohol spinning membrane; S2, drying the polyvinyl alcohol spinning membrane, and hot pressing to obtain a polyvinyl alcohol spinning membrane; S3, placing the polyvinyl alcohol spinning membrane in a crosslinking agent solution for crosslinking, and drying to obtain a crosslinked modified polyvinyl alcohol spinning membrane; S4. Compounding the perfluorosulfonic acid solution and the cross-linked modified polyvinyl alcohol spinning membrane by a casting method to obtain a cross-linked polyvinyl alcohol composite spinning membrane.
[0005] Electrospinning is a process that uses high-voltage electrostatic forces to propel a polymer solution (or melt) into a jet to form polymer fibers. Electrospinning nanofiber production offers the advantages of low cost, ease of operation, and the ability to continuously produce nanofibers with controllable morphology. Nanofiber materials produced via electrospinning have broad application prospects in the field of battery separators.
[0006] As a further technical solution, during the electrospinning, the spinning rate is 0.1-0.8 mL / h, the spinning voltage is 12-20 kV, and the distance between the spinneret and the receiving device is 10-20 cm.
[0007] As a further technical solution, the method for preparing the polyvinyl alcohol spinning solution comprises the following steps: The polyvinyl alcohol and the organic solvent are preliminarily mixed, and a surfactant is added and continued to mix to obtain the polyvinyl alcohol spinning solution.
[0008] As a further technical solution, a vacuum degassing treatment is also performed after the mixing; The mass of the polyvinyl alcohol is 7% to 12% of the mass of the polyvinyl alcohol spinning solution; The mass of the surfactant is 0.1% to 0.5% of the mass of the polyvinyl alcohol; The initial mixing temperature is 40-80°C and the mixing time is 2-6 hours; The mixing temperature is 80-110° C. and the mixing time is 1-3 hours.
[0009] As a further technical solution, in step S2, the drying treatment temperature is 60-100°C and the time is 0.5-2.0h.
[0010] As a further technical solution, during the hot pressing, the temperature is 60-120° C., the pressure is 0.2-2 MPa, and the time is 5-20 min.
[0011] As a further technical solution, in the cross-linking agent solution, the mass of the cross-linking agent is 20% to 25% of the mass of the solvent; The cross-linking agent includes an aldehyde cross-linking agent; The pH of the cross-linking agent solution is 1.5 to 2.5; The cross-linking temperature is 60-65° C., and the cross-linking time is 25-35 minutes.
[0012] As a further technical solution, the aldehyde cross-linking agent includes glutaraldehyde.
[0013] As an efficient cross-linking agent, glutaraldehyde can introduce strong cross-linking chains by condensing with the hydroxyl groups in the PVA molecular chain, thereby making the PVA material have better mechanical properties and anti-swelling properties, as well as good chemical stability.
[0014] As a further technical solution, the drying temperature is 60-65°C.
[0015] As a further technical solution, in step S4, the mass of perfluorosulfonic acid in the perfluorosulfonic acid solution is 3% to 6% of the mass of the solvent.
[0016] As a further technical solution, the mass ratio of polyvinyl alcohol and perfluorosulfonic acid in the cross-linked polyvinyl alcohol composite spinning membrane is 1:2-6.
[0017] As a further technical solution, the cross-linking agent comprises an aldehyde cross-linking agent; and the surfactant comprises an anionic surfactant. The organic solvent comprises one or more of N,N-dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, acetone, and ethanol. The surfactant comprises an anionic surfactant. The organic solvent comprises one or more of N,N-dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, acetone, and ethanol. The component A is further added during the initial mixing. The mass of the component A is 5%-10% of the mass of the polyvinyl alcohol. The component A comprises hydroxypropyl cellulose, cellulose acetate, and silicon dioxide at a mass ratio of 1:3:0.5-3.
[0018] In the present application, the method of adding hydroxypropyl cellulose and cellulose acetate cooperatively and silicon dioxide to the polyvinyl alcohol spinning solution significantly improves the strength of the spinning membrane. Hydroxypropyl cellulose forms a large number of hydrogen bonds with polyvinyl alcohol by virtue of the rich hydroxyl groups on the molecular chain, tightly binds the molecular chain, and enhances the cohesive strength, while taking into account the flexibility. Cellulose acetate promotes the ordered arrangement of polyvinyl alcohol molecular chains with its regular structure, improves the crystallinity, and the interaction between the ester groups and polyvinyl alcohol further stabilizes the internal structure. Silicon dioxide, as a high-hardness and rigid inorganic filler, uniformly disperses in the spinning membrane to bear stress and prevent crack propagation. Hydroxypropyl cellulose and cellulose acetate disperse silicon dioxide and promote the combination between silicon dioxide and polyvinyl alcohol, so that the cross-linked polyvinyl alcohol composite spinning membrane can withstand greater external forces such as tension and pressure, reduce problems such as rupture and damage caused by insufficient strength, and improve the strength of the cross-linked polyvinyl alcohol composite spinning membrane.
[0019] As a further technical solution, the anionic surfactant comprises one or more of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium lignosulfonate.
[0020] The present application also provides a cross-linked polyvinyl alcohol composite spinning membrane prepared by the preparation method.
[0021] The working principle and beneficial effects of the present application are as follows: In the present application, polyvinyl alcohol is a good film-forming material, belongs to the water-priority type membrane, has good separation effect on water-organic matter, shows good alcohol resistance and good proton conductivity. However, the molecular chains lack cross-linking, and the PVA membrane is easily dissolved and broken in water. In the present application, the polyvinyl alcohol membrane prepared by electrospinning is modified by cross-linking with glutaraldehyde and then heat-pressed, and is compounded with perfluorosulfonic acid, so that the water resistance and swelling resistance of the proton exchange membrane are improved, and the proton conductivity of the membrane is increased. The existing technology solves the problems of the perfluorosulfonic acid proton exchange membrane, such as easy swelling, poor water resistance and the like. DETAILED DESCRIPTION
[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor also fall within the scope of protection of the present application.
[0023] Embodiment 1 The preparation method of the cross-linked polyvinyl alcohol composite spinning membrane comprises the following steps: S1, dissolve PVA powder in NMP, stir at 60℃ for 4h, add SDS after PVA is completely dissolved, heat and stir at 90℃ for 2h until the high molecular solution becomes homogeneous, viscous and transparent, and then place at room temperature until constant temperature; the mass fraction of PVA in the high molecular solution is 9%, and the mass of SDS is 0.25% of the mass of PVA; S2, vacuum degassing treatment is performed on the high molecular solution to obtain a polyvinyl alcohol spinning solution; S3, prepare a polyvinyl alcohol spinning membrane by using an electrospinning device: add the polyvinyl alcohol spinning solution into the syringe of the electrospinning device, and perform electrospinning at a spinning rate of 0.6mL / h, a spinning voltage of 16kV and a distance of 15cm between the spinning nozzle and the receiving device to obtain a spinning membrane; S4, dry the spinning membrane to remove residual organic solvents in the membrane, and the drying temperature is 60℃ and the drying time is 1h; S5, heat-press the spinning membrane at 60℃ and 1MPa for 10min to obtain a polyvinyl alcohol spinning membrane; S6, cross-linking modification is performed on the polyvinyl alcohol spinning membrane: place the polyvinyl alcohol spinning membrane in a mixed solution prepared by dilute hydrochloric acid and deionized water, with pH=2 and the mass fraction of glutaraldehyde being 25%, and perform cross-linking reaction at 60℃ for 30min, then dry at 60℃ after the reaction is completed, finally soak the membrane in deionized water and then dry to obtain a cross-linked polyvinyl alcohol spinning membrane; S7, dissolve the PFSA powder in NMP, the PFSA content is 5%, react in the reaction kettle at 150℃ for 4h, obtain the perfluorosulfonic acid solution; S8, prepare the composite membrane by casting method: lay the crosslinked polyvinyl alcohol spinning membrane in the membrane pool, cast the perfluorosulfonic acid solution in the membrane pool, after the perfluorosulfonic acid solution is fully infiltrated, move to the oven for drying at 80℃ for 8h, obtain the crosslinked polyvinyl alcohol composite spinning membrane; in the crosslinked polyvinyl alcohol composite spinning membrane, the mass ratio of PVA and PFSA is 1:3.
[0024] Example 2 The difference between this example and example 1 is only that in the crosslinked polyvinyl alcohol composite spinning membrane, the mass ratio of PVA and PFSA is 1:4.
[0025] Example 3 The difference between this example and example 1 is only that in the crosslinked polyvinyl alcohol composite spinning membrane, the mass ratio of PVA and PFSA is 1:5.
[0026] Example 4 The preparation method of the crosslinked polyvinyl alcohol composite spinning membrane comprises the following steps: S1, dissolve the PVA powder in NMP, stir at 40℃ for 6h, after the PVA is completely dissolved, add SDS, heat and stir at 80℃ for 3h, until it becomes a homogeneous viscous transparent polymer solution, place it at room temperature until it reaches a constant temperature; the mass fraction of PVA in the polymer solution is 7%, and the mass of SDS is 0.1% of the mass of PVA; S2, vacuum degassing treatment is performed on the polymer solution to obtain a polyvinyl alcohol spinning solution; S3, prepare a polyvinyl alcohol spinning membrane by using an electrospinning device: add the polyvinyl alcohol spinning solution to the syringe of the electrospinning device, perform electrospinning at a spinning rate of 0.1mL / h, a spinning voltage of 12kV, and a distance between the spinning nozzle and the receiving device of 10cm, to obtain a spinning membrane; S4, dry the spinning membrane to remove residual organic solvents in the membrane, the drying temperature is 60℃, and the drying time is 2h; S5, hot-press the spinning membrane at 60℃ and 2MPa for 5min to obtain a polyvinyl alcohol spinning membrane; S6, crosslink and modify the polyvinyl alcohol spinning membrane: place the polyvinyl alcohol spinning membrane in a mixed solution prepared by dilute hydrochloric acid and deionized water, with a pH of 1.5 and a glutaraldehyde mass fraction of 20%, and perform crosslinking reaction at 60℃ for 35min, after the reaction is completed, dry it at 60℃, finally, place the membrane in deionized water for soaking and then dry it, to obtain a crosslinked polyvinyl alcohol spinning membrane; S7, dissolve PFSA powder in NMP, the content of PFSA is 3%, react in a reaction kettle at 150℃ for 4h, obtain a perfluorosulfonic acid solution; S8, prepare a composite membrane by casting method: lay the crosslinked polyvinyl alcohol spinning membrane in the membrane pool, cast the perfluorosulfonic acid solution in the membrane pool, after the perfluorosulfonic acid solution is fully infiltrated, move to the oven to dry at 80℃ for 8h, obtain the crosslinked polyvinyl alcohol composite spinning membrane; in the crosslinked polyvinyl alcohol composite spinning membrane, the mass ratio of PVA and PFSA is 1:2.
[0027] Example 5 The preparation method of the crosslinked polyvinyl alcohol composite spinning membrane comprises the following steps: S1, dissolve PVA powder in NMP, stir at 80℃ for 2h, after PVA is completely dissolved, add SDS, heat and stir at 110℃ for 1h, until it becomes a homogeneous viscous transparent polymer solution, place it at room temperature until it reaches a constant temperature; the mass fraction of PVA in the polymer solution is 12%, and the mass of SDS is 0.5% of the mass of PVA; S2, vacuum degassing treatment is performed on the polymer solution to obtain a polyvinyl alcohol spinning solution; S3, prepare a polyvinyl alcohol spinning membrane by using an electrospinning device: add the polyvinyl alcohol spinning solution to the syringe of the electrospinning device, electrospin at a spinning rate of 0.8mL / h, a spinning voltage of 12kV, and a distance between the spinning nozzle and the receiving device of 20cm, to obtain a spinning membrane; S4, dry the spinning membrane to remove residual organic solvents in the membrane, the drying temperature is 100℃, and the drying time is 0.5h; S5, hot-press the spinning membrane at 120℃ and 0.2MPa for 5min to obtain a polyvinyl alcohol spinning membrane; S6, crosslink and modify the polyvinyl alcohol spinning membrane: place the polyvinyl alcohol spinning membrane in a mixed solution prepared by dilute hydrochloric acid and deionized water, with a pH of 2.5 and a glutaraldehyde mass fraction of 25%, and perform crosslinking reaction at 65℃ for 25min, after the reaction is completed, dry it at 65℃, finally soak the membrane in deionized water and then dry it, to obtain a crosslinked polyvinyl alcohol spinning membrane; S7, dissolve PFSA powder in NMP, the content of PFSA is 6%, react in a reaction kettle at 150℃ for 4h, obtain a perfluorosulfonic acid solution; S8, prepare a composite membrane by casting method: lay the crosslinked polyvinyl alcohol spinning membrane in the membrane pool, cast the perfluorosulfonic acid solution in the membrane pool, after the perfluorosulfonic acid solution is fully infiltrated, move to the oven to dry at 80℃ for 8h, obtain the crosslinked polyvinyl alcohol composite spinning membrane; in the crosslinked polyvinyl alcohol composite spinning membrane, the mass ratio of PVA and PFSA is 1:6.
[0028] Example 6 The difference between this embodiment and embodiment 1 is only that step S1 is: taking PVA powder to dissolve in NMP, adding component A, stirring at 60℃ for 4h, adding SDS after PVA is completely dissolved, heating and stirring at 90℃ for 2h, until becoming a homogeneous viscous transparent polymer solution, and placing at room temperature until constant temperature; the mass fraction of PVA in the polymer solution is 9%, the mass of SDS is 0.25% of the mass of PVA, and the mass of component A is 5% of the mass of polyvinyl alcohol; component A is hydroxypropyl cellulose and silicon dioxide with a mass ratio of 1:0.5.
[0029] Embodiment 7 The difference between this embodiment and embodiment 6 is only that component A is cellulose acetate and silicon dioxide with a mass ratio of 3:0.5.
[0030] Embodiment 8 The difference between this embodiment and embodiment 6 is only that component A is hydroxypropyl cellulose, cellulose acetate and silicon dioxide with a mass ratio of 1:3:0.5.
[0031] Embodiment 9 The difference between this embodiment and embodiment 1 is only that step S1 is: taking PVA powder to dissolve in NMP, adding component A, stirring at 60℃ for 4h, adding SDS after PVA is completely dissolved, heating and stirring at 90℃ for 2h, until becoming a homogeneous viscous transparent polymer solution, and placing at room temperature until constant temperature; the mass fraction of PVA in the polymer solution is 9%, the mass of SDS is 0.25% of the mass of PVA, and the mass of component A is 10% of the mass of polyvinyl alcohol; component A is hydroxypropyl cellulose, cellulose acetate and silicon dioxide with a mass ratio of 1:3:3.
[0032] Comparative Example 1 The difference between this comparative example and embodiment 2 is only that step S6 is not included, i.e., the polyvinyl alcohol spinning film is not cross-linked and modified.
[0033] Comparative Example 2 The difference between this comparative example and embodiment 2 is only that step S5 is not included, i.e., the hot-pressing treatment is not performed.
[0034] Comparative Example 3 The preparation method of the cross-linked polyvinyl alcohol composite spinning film comprises the following steps: S1, taking PVA powder to dissolve in NMP, stirring at 60℃ for 4h, and obtaining a PVA solution with a solid content of 9% after PVA is completely dissolved; S2, taking PFSA powder to dissolve in NMP, the content of PFSA is 5%, and a perfluorosulfonic acid solution is obtained by reacting in a reaction kettle at 150℃ for 4h; S3, take the PVA solution and the perfluorosulfonic acid solution, stir at room temperature for 2h, to obtain a composite solution; S4, the obtained composite solution is cast in a film cell and placed in an oven for drying at 80°C for 8h to obtain a composite proton exchange membrane, and the mass fraction of PVA:PFSA in the composite membrane is 1:4; S5, the composite membrane is modified by crosslinking, and the modification method is as follows: the polyvinyl alcohol spinning membrane is placed in a mixed solution prepared by dilute hydrochloric acid and deionized water with pH=2 and 25% of glutaraldehyde mass fraction for crosslinking, and the temperature is raised to 60°C for reaction for 30min, after the reaction is completed, the membrane is dried at 60°C, and finally the membrane is soaked in deionized water and then dried to obtain the crosslinked modified composite membrane.
[0035] Comparative Example 4 The difference between this comparative example and Example 2 is only that step S5 is as follows: the polyvinyl alcohol spinning membrane is modified by crosslinking: the polyvinyl alcohol spinning membrane is placed in a mixed solution prepared by dilute hydrochloric acid and deionized water with pH=2 and 25% of glutaraldehyde mass fraction for crosslinking at 60°C for 30min, after the reaction is completed, the membrane is dried at 60°C, and finally the membrane is soaked in deionized water and then dried to obtain the crosslinked polyvinyl alcohol spinning membrane. Step S6 is as follows: the spinning membrane is hot-pressed at 60°C and 1MPa for 10min to obtain the polyvinyl alcohol spinning membrane.
[0036] Comparative Example 5 The difference between this comparative example and Example 2 is only that the pressure in the hot-pressing treatment in step S5 is 3MPa.
[0037] Experimental Example 1 The crosslinked polyvinyl alcohol composite spinning membranes prepared in Examples 1-5 and Comparative Examples 1-5 are respectively tested for proton conductivity, water absorption rate, hydrolysis stability, water swelling rate, tensile strength, and limiting current density, and the results are shown in Table 1 below.
[0038] Among them, the proton conductivity: the CHI600E type electrochemical workstation of Shanghai Chenhua Instrument Co., Ltd. is used to determine the proton conductivity of the film by alternating current impedance method. Before testing, the film is soaked in deionized water for 24h to make it fully hydrated, then the film is placed in the middle of the clamp, the interference voltage is set to 10mV, and the test frequency is 1-10 6 Hz. The test is carried out in deionized water, and the calculation formula of the proton conductivity σ (S / cm) is as follows.
[0039]
[0040] In the formula: a-distance between two electrodes (cm); R-sample impedance (Ω); b - film effective length (cm); d - sample thickness (cm).
[0041] Water absorption: The sample was dried in an 80°C oven for 24 h. The sample weight m0was measured. The sample was immersed in room temperature deionized water for 8 h. Then, the surface water of the sample was removed with filter paper, and its mass was measured within 30 s and recorded as m1. The water content value of the film, Δm, was calculated by the following formula:
[0042] wherein: m0- the mass of the dry film (g); m1- the mass of the wet film (g).
[0043] Hydrolytic stability: The sample was dried in an 80°C oven for 24 h, and the sample weight was measured as W0. The sample was immersed in 80°C deionized water for 48 h. The film was taken out and dried at 80°C for 8 h, and the weight was measured as W t . The hydrolytic stability value of the film, W c , was calculated by the following formula:
[0044] wherein: W0- the mass of the dry film (g); W t - the mass of the remaining film (g); Swelling in water: The film was dried and cut into a size of 5 cm x 5 cm, and the diagonal length was measured as D d . It was placed in deionized water and immersed at room temperature for 24 h. After 24 h, it was taken out, and the diagonal length of the film after immersion was measured as D w . The swelling in water value, ΔD, was calculated by the following formula:
[0045] wherein: D d - the diagonal length of the dry film (cm); D w - the diagonal length of the wet film (cm); Tensile strength: The mechanical properties of the sample were tested by using a TSL-1002 universal tensile testing machine of Jinan Sike Testing Technology Co., Ltd. The original gauge length was 65 mm, and the tensile speed was 5 mm / min. The tensile strength of the film was calculated by the following formula:
[0046] wherein: P - the maximum load (N); d - the film thickness (mm); b - the film width (mm).
[0047] Limiting current density: In the measurement of the internal current of the fuel cell, the cathode supplies humidified nitrogen, and the anode supplies humidified hydrogen. The relative humidity of the gas (nitrogen, hydrogen) is 90%. The absolute pressure of the hydrogen and nitrogen gas inlet is 110 kPa, and the flow rates are 1.67 x 10 -5 m 3 •s -1 and 3.33 x 10 -5 m 3 •s -1 , the temperature of the fuel cell is 80℃, and the linear potential scanning is performed by using the electrochemical workstation of Shanghai Chenhua Company. During the measurement, the working electrode is connected with the cathode current collector plate, and the counter electrode and the reference electrode are connected with the anode current collector plate. The voltage scanning range is set to 0.1-0.8V, and the scanning speed is 2mV / s. The charging current and the voltage response are recorded by the acquisition system, and the acquisition frequency is 10000Hz. The current density can be obtained by the formula: current density (J) = current (I) / effective area of the battery (A), and the hydrogen permeation amount is represented by the limiting current density.
[0048] Table 1 Performance test results
[0049] It can be known from the comparison between Comparative Example 2 and Comparative Example 1 that after the polyvinyl alcohol spinning film is cross-linked and modified by glutaraldehyde, the overall performance of the composite film is improved, and the hydrolysis stability and the swelling rate are obviously improved.
[0050] It can be known from the comparison between Comparative Example 2 and Comparative Example 2 that if the hot pressing link in the film preparation process is reduced, the dimensional stability of the diaphragm is poor, the mechanical strength is reduced, thereby affecting the proton conductivity of the diaphragm, and the battery performance is poor.
[0051] It can be known from the comparison between Comparative Example 2 and Comparative Example 3 that the diaphragm prepared by the electrostatic spinning method has better performance than the conventional mixed casting method, can greatly improve the mechanical strength of the diaphragm, is beneficial to the stability of the diaphragm in water, and simultaneously increases the proton conduction performance of the diaphragm. Therefore, the electrostatic spinning method has strong advantages in the field of proton membrane preparation.
[0052] It can be known from the comparison between Comparative Example 2 and Comparative Example 4 that after the polyvinyl alcohol film is cross-linked and modified and then subjected to hot pressing treatment, the molecular chain may be broken, and the cross-linked network may be damaged. From the performance, the water resistance of the diaphragm is poor, the tensile strength is reduced, and the overall performance is poor.
[0053] It can be known from the comparison between Comparative Example 2 and Comparative Example 5 that excessive increase of the hot pressing pressure causes the internal structure of the diaphragm to collapse, the proton transmission channel is damaged, and the proton conductivity is obviously reduced.
[0054] Experimental Example 2 The crosslinked polyvinyl alcohol composite spinning films prepared in Examples 6-9 were subjected to tensile strength test (the test method was according to the tensile strength test method of Experimental Example 1), and the results are shown in Table 2 below.
[0055] Table 2 Tensile strength test results
[0056] Compared with Examples 1, 6-7, the crosslinked polyvinyl alcohol composite spinning films prepared in Examples 8-9 have higher tensile strength, which indicates that the use of hydroxypropyl cellulose and cellulose acetate in component A in combination with the addition of silicon dioxide to the polyvinyl alcohol spinning solution improves the strength of the crosslinked polyvinyl alcohol composite spinning film.
[0057] The above only describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for preparing a cross-linked polyvinyl alcohol composite spinning membrane, characterized in that: The following steps are involved: S1, taking polyvinyl alcohol spinning solution and performing electrospinning to obtain polyvinyl alcohol spinning membrane; S2, drying the polyvinyl alcohol spinning membrane, and hot pressing to obtain a polyvinyl alcohol spinning membrane; S3, placing the polyvinyl alcohol spinning membrane in a crosslinking agent solution for crosslinking, and drying to obtain a crosslinked modified polyvinyl alcohol spinning membrane; S4. Compounding the perfluorosulfonic acid solution and the cross-linked modified polyvinyl alcohol spinning membrane by a casting method to obtain a cross-linked polyvinyl alcohol composite spinning membrane.
2. The method for preparing a cross-linked polyvinyl alcohol composite spinning membrane according to claim 1, wherein: During the electrostatic spinning, the spinning rate is 0.1-0.8 mL / h, the spinning voltage is 12-20 kV, and the distance between the spinneret and the receiving device is 10-20 cm.
3. The method for preparing a cross-linked polyvinyl alcohol composite spinning membrane according to claim 1, wherein: The method for preparing the polyvinyl alcohol spinning solution comprises the following steps: The polyvinyl alcohol and the organic solvent are preliminarily mixed, and a surfactant is added and continued to mix to obtain the polyvinyl alcohol spinning solution.
4. The method for preparing a cross-linked polyvinyl alcohol composite spinning membrane according to claim 3, wherein: After the mixing, a vacuum degassing treatment is also performed; The mass of the polyvinyl alcohol is 7% to 12% of the mass of the polyvinyl alcohol spinning solution; The mass of the surfactant is 0.1% to 0.5% of the mass of the polyvinyl alcohol; The initial mixing temperature is 40-80°C and the mixing time is 2-6 hours; The mixing temperature is 80-110° C. and the mixing time is 1-3 hours.
5. The method for preparing a cross-linked polyvinyl alcohol composite spinning membrane according to claim 1, wherein: In step S2, during the hot pressing, the temperature is 60-120° C., the pressure is 0.2-2 MPa, and the time is 5-20 min.
6. The method for preparing a cross-linked polyvinyl alcohol composite spinning membrane according to claim 1, wherein: In step S1, in the cross-linking agent solution, the mass of the cross-linking agent is 20% to 25% of the mass of the solvent; The cross-linking agent includes an aldehyde cross-linking agent; The pH of the cross-linking agent solution is 1.5 to 2.5; The cross-linking temperature is 60-65° C., and the cross-linking time is 25-35 minutes.
7. The method for preparing a cross-linked polyvinyl alcohol composite spinning membrane according to claim 1, wherein: In step S4, in the perfluorosulfonic acid solution, the mass of perfluorosulfonic acid is 3% to 6% of the mass of the solvent.
8. The method for preparing a cross-linked polyvinyl alcohol composite spinning membrane according to claim 7, characterized in that: In the cross-linked polyvinyl alcohol composite spinning membrane, the mass ratio of polyvinyl alcohol to perfluorosulfonic acid is 1:2-6.
9. The method for preparing a cross-linked polyvinyl alcohol composite spinning membrane according to claim 3, characterized in that: The surfactant includes an anionic surfactant; The organic solvent includes one or more of N,N-dimethylformamide, N-methylpyrrolidone, tetrahydrofuran, acetone, and ethanol; During the initial mixing, component A is also added; The mass of the component A is 5% to 10% of the mass of the polyvinyl alcohol; The component A comprises hydroxypropyl cellulose, cellulose acetate and silicon dioxide in a mass ratio of 1:3:0.5-3.
10. A cross-linked polyvinyl alcohol composite spinning membrane, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.