A method for preparing a hydrophilic conductive polyphenylene sulfide fiber

Abstract

The application provides a preparation method of hydrophilic conductive polyphenylene sulfide fibers and belongs to the technical field of textile fiber preparation. The conductive additive, the hydrophilic additive and the polyphenylene sulfide resin are melt-blended by using a double-screw extruder, and then spinning is performed to obtain the hydrophilic conductive polyphenylene sulfide fibers. The double-screw multi-zone high-pressure high-shear interactive in-situ grafting technology is used to complete the fiber preparation in one step through melt blending and spinning forming, the hydrophilic additive is loaded on the conductive additive, the dispersibility of the conductive additive and the compatibility with the PPS matrix are improved, the uniformly dispersed conductive additive can form a crosslinked network structure in the PPS matrix, and the conductivity and the hydrophilic property of the polyphenylene sulfide fibers are improved.

Description

Technical Field

[0001] This invention relates to the field of textile fiber preparation technology, and in particular to a method for preparing hydrophilic conductive polyphenylene sulfide fiber. Background Technology

[0002] With the development and research of key technologies and equipment for high-efficiency, high-power alkaline water electrolyzers, the technological breakthrough of polyphenylene sulfide (PPS) diaphragms used in hydrogen production alkaline electrolyzers is of paramount importance. Diaphragm materials are a crucial component of alkaline electrolyzers, serving three main functions: ① separating the cathode and anode to form cathode and anode chambers, preventing short circuits; ② preventing the mixing of gaseous products at the two electrodes; ③ possessing high ionic conductivity to facilitate the transfer of hydroxide ions from the cathode to the anode. Therefore, an ideal diaphragm material should possess the following characteristics: ① good ionic conductivity, high porosity, and low resistivity; ② high gas barrier properties, high hydrophilicity, and high corrosion resistance; ③ thin thickness, small pore size, high mechanical strength, and good dimensional stability; ④ low cost and long service life (generally 10 years).

[0003] PPS fiber possesses excellent thermal stability, chemical stability, corrosion resistance, and flame retardancy, making it a primary raw material for diaphragms in alkaline electrolyzers for hydrogen production. However, the lack of polar groups in the PPS molecular chain results in poor hydrophilicity and conductivity. Direct application leads to high resistivity and high power consumption in hydrogen electrolysis, potentially causing safety accidents. Therefore, the conventional technique for improving the hydrophilicity of PPS fiber diaphragms involves sulfonation of the base membrane with a strong oxidizing acid. This introduces sulfonic acid groups (-SO3H) into the macromolecular chain, improving the material's hydrophilicity. However, sulfonation has drawbacks. While improving hydrophilicity, it causes swelling, and the surface becomes rough due to acid etching. Insufficient or excessive sulfonation negatively impacts the material's mechanical properties. Furthermore, the sulfonic acid groups react with KOH in the alkaline electrolyzer during subsequent use, gradually depleting the hydrophilicity. Summary of the Invention

[0004] In view of this, the present invention aims to provide a method for preparing hydrophilic conductive polyphenylene sulfide (PPS) fibers. This invention proposes a twin-screw multi-zone high-pressure high-shear interactive in-situ grafting technology, which improves the dispersibility of conductive additives and their compatibility with the PPS matrix. The uniformly dispersed conductive additives can form a cross-linked network structure in the PPS matrix, improving the hydrophilicity and conductivity of the PPS fibers. Simultaneously, melt blending and spinning are completed in one step, which not only improves the preparation efficiency but also effectively protects the additives and avoids excessive oxidative degradation.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] One of the technical solutions of the present invention is a method for preparing hydrophilic conductive polyphenylene sulfide fiber, which involves using a twin-screw extruder to melt-blend conductive additives, hydrophilic additives and polyphenylene sulfide resin, followed by spinning to obtain the hydrophilic conductive polyphenylene sulfide fiber.

[0007] The twin-screw extruder is configured with ten zones. In zone one, a main feed port and an auxiliary feed port 1 are set up, and polyphenylene sulfide resin and conductive additives are added to the main feed port and the auxiliary feed port 1, respectively. In zone two, heating and conveying are carried out using a large-lead screw element. In zone three, a feed port 2 is set up, and hydrophilic additives are added to the feed port 2. After the material is fully melted in zones four and five, it is subjected to high-pressure shearing in zones six and seven, kneading in zone eight, homogenization in zone nine, and extrusion in zone ten.

[0008] The second technical solution of the present invention is a hydrophilic conductive polyphenylene sulfide fiber prepared by the above preparation method.

[0009] The third technical solution of the present invention is a hydrophilic conductive polyphenylene sulfide fiber fabric type alkaline water electrolysis membrane, which is obtained by weaving the above-mentioned hydrophilic conductive polyphenylene sulfide fiber.

[0010] The fourth technical solution of the present invention is the application of the above-mentioned hydrophilic conductive polyphenylene sulfide fiber fabric type alkaline water electrolysis membrane in water electrolysis for hydrogen production.

[0011] The present invention discloses the following technical effects:

[0012] This invention addresses the shortcomings of ordinary polyphenylene sulfide (PPS) fibers, such as poor conductivity and hygroscopicity, which prevent their direct application in alkaline water electrolysis hydrogen production membranes. By using MWCNT and PAAS melt blending, a melt in-situ grafting extrusion and direct spinning technique was developed to prepare modified PPS fibers with good conductivity and hydrophilicity, resulting in significant technological advantages and market competitiveness.

[0013] The hydrophilic conductive polyphenylene sulfide (PPS) fiber obtained in this invention has a combined network structure of MWCNTs in the matrix. The conductivity of the PPS fiber is effectively improved by utilizing the inherent conductivity of carbon nanotubes grafted onto the PAAS surface. The conductivity is increased from 2.98 × 10⁻⁶ for the original pure PPS fiber. -13 The S / cm ratio can be increased to a maximum of 1.15 × 10⁻⁶ for modified fibers. -2 The S / cm ratio was increased by 11 orders of magnitude; the excellent hydrophilicity of PAAS itself effectively improved the hygroscopicity and hydrophilicity of PPS fibers, with a water contact angle of up to 43.5°. This expands its application in the field of alkaline water electrolysis for hydrogen production. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 The images shown are SEM-EDS images of hydrophilic conductive polyphenylene sulfide fibers in Example 1, where the left image is the SEM image and the right image is the sodium element EDS image of the corresponding region in the SEM image.

[0016] Figure 2 The water contact angle of the hydrophilic conductive polyphenylene sulfide fiber in Example 1;

[0017] Figure 3 The conductivity is that of the hydrophilic conductive polyphenylene sulfide fiber in Example 1. Detailed Implementation

[0018] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0019] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0020] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0021] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0022] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0023] To improve the hydrophilicity and conductivity of polyphenylene sulfide (PPS) fibers, this invention proposes an in-situ modification method for preparing hydrophilic and conductive PPS fibers. This invention directly utilizes a twin-screw extruder to melt-blend multi-walled carbon nanotubes (MWCNTs) and the hydrophilic additive sodium polyacrylate (PAAS) with PPS resin, followed by extrusion and stretching via a spinneret to prepare composite PPS fibers. This invention introduces conductive MWCNTs and the hydrophilic additive sodium polyacrylate into the PPS matrix. While maintaining the excellent chemical resistance of PPS fibers, this invention designs and develops a twin-screw melt reactive extrusion spinning technology. High-pressure melt zones are established in the middle and rear sections of the twin-screw using pressure-building reverse thread elements. High-shear and high-mixing thread elements are placed within these melt zones, causing MWCNTs and PAAS to adsorb and graft, improving the dispersibility of MWCNTs. Simultaneously, PAAS, while increasing the fiber's hydrophilicity, helps MWCNTs form a network structure, thereby improving the conductivity of the PPS fibers.

[0024] The first aspect of the present invention provides a method for preparing hydrophilic conductive polyphenylene sulfide fiber, wherein a conductive additive, a hydrophilic additive and a polyphenylene sulfide resin are melt-blended using a twin-screw extruder, and then spun to obtain the hydrophilic conductive polyphenylene sulfide fiber;

[0025] The twin-screw extruder is configured with ten zones. Zones one through four are feeding, conveying, and melting zones. Zone one has a main feed port and an auxiliary feed port 1, where polyphenylene sulfide resin and conductive additives are added respectively. Zone two uses a large-lead threaded element for heating and conveying. Zone three has a feed port 2, where hydrophilic additives are added. After the material is fully melted in zones four and five, it undergoes high-pressure shearing in zones six and seven, kneading in zone eight, homogenization in zone nine, and extrusion in zone ten. This invention utilizes a reverse threaded element to set two pressure-building zones in zones six and seven, where triangular kneading elements and pin-type mixing elements are configured to increase shear stress and enhance interaction. In zone eight, a toothed kneading element is configured for kneading. Zone ten is the die head zone, where the melt obtained after homogenization in zone nine is extruded, followed by subsequent spinning steps.

[0026] In some embodiments of the present invention, before the conductive additive, the hydrophilic additive and the polyphenylene sulfide resin are melt-blended, the present invention further includes a step of drying the conductive additive, the hydrophilic additive and the polyphenylene sulfide resin to a moisture content ≤0.006%.

[0027] The conductive additive is multi-walled carbon nanotubes; the hydrophilic additive is sodium polyacrylate; the multi-walled carbon nanotubes account for 2.5-4% of the total mass of polyphenylene sulfide resin, multi-walled carbon nanotubes and sodium polyacrylate; the sodium polyacrylate accounts for 0.1-1.5% of the total mass of polyphenylene sulfide resin, multi-walled carbon nanotubes and sodium polyacrylate. In this invention, a weighing error of ±2g is allowed when weighing polyphenylene sulfide resin, multi-walled carbon nanotubes and sodium polyacrylate.

[0028] In some embodiments of the present invention, the temperature configuration of each zone of the twin-screw extruder is as follows: Zone 1 270℃±5℃, Zone 2 282℃±5℃, Zone 3 285℃±5℃, Zone 4 287℃±5℃, Zone 5 289℃±5℃; Zone 6 291℃±5℃, Zone 7 294℃±5℃, Zone 8 295℃±5℃, Zone 9 300℃±5℃, Zone 10 302℃±5℃;

[0029] The melt pressure in zones 6 and 10 is 7–8.5 MPa.

[0030] In some embodiments of the present invention, the spinning process specifically involves: after melt blending, the melt is extruded through ten zones into a curved tube, then enters a metering pump through the curved tube, and after precise metering, enters a spinning box. Inside the box, it enters a spinning assembly, is extruded through a spinneret to form a fine melt stream, and is then cooled and shaped by a ring blower. The fiber is stretched in two stages using three hot plates and two hot boxes, wherein the temperature of the first hot plate is 90℃±1℃, the temperature of the second hot plate is 92℃±2℃, the temperature of the third hot plate is 92℃±2℃, the temperature of the first hot box is 110℃±2℃, the temperature of the second hot box is 112℃±2℃, the total stretching ratio is 3 to 5 times, and the stretching zones are configured as a small zone in the first zone and a large zone in the second zone.

[0031] In some embodiments of the present invention, the set temperature of the bend, metering pump and housing is 300℃±5℃.

[0032] MWCNTs are one-dimensional nanomaterials. Multiple studies have shown that they exhibit poor dispersion and compatibility in polymer materials. While they can enhance and toughen polymers when their mass fraction is below 1%, significant agglomeration occurs with higher concentrations. Therefore, this invention proposes using PAASs as a bridge, establishing a high-pressure, high-shear environment to induce grafting reactions between PAASs and the surface amino groups of MWCNTs, acting as a compatibilizer. This improves both the dispersibility of MWCNTs and their compatibility with the PPS matrix. However, MWCNTs and PAASs do not spontaneously react with each other. Numerous experiments have shown that conventional techniques cannot induce this interaction. Furthermore, PAASs are prone to decomposition and vaporization at prolonged high temperatures, failing to improve hydrophilicity and reducing the thermal stability and mechanical properties of the PPS matrix. Therefore, this invention proposes a one-step twin-screw in-situ reaction melt spinning technology. By establishing multiple high-pressure reaction zones, the high-temperature time is relatively reduced. After melt blending, the fibers are directly spun, eliminating the intermediate granulation step and avoiding the damage to the grafted composite by secondary melting. This results in hydrophilic and conductive PPS composite fibers, achieving better technical effects.

[0033] A second aspect of the present invention provides a hydrophilic conductive polyphenylene sulfide fiber prepared by the above preparation method.

[0034] A third aspect of the present invention provides a hydrophilic conductive polyphenylene sulfide fiber fabric type alkaline water electrolysis membrane, which is obtained by weaving the above-mentioned hydrophilic conductive polyphenylene sulfide fiber.

[0035] The fourth aspect of the present invention provides an application of the above-mentioned hydrophilic conductive polyphenylene sulfide fiber fabric type alkaline water electrolysis membrane in water electrolysis for hydrogen production.

[0036] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0037] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0038] The polyphenylene sulfide resin used in the examples is a linear polyphenylene sulfide resin (C6H4S). n Slices, solid particles, diameter ≤3mm, melting point 280~290℃; the multi-walled carbon nanotubes are multi-walled carbon nanotubes with surface amination treatment, solid powder, which can be obtained by surface amination treatment of multi-walled carbon nanotubes using a technique well known to those skilled in the art, or commercially available; sodium polyacrylate (C3H3NaO2). n ), solid powder.

[0039] Example 1

[0040] (1) Weigh the polyphenylene sulfide resin chips and place them in a vacuum drum dryer. Set the drying temperature to 135℃, maintain the vacuum degree inside the drum at -0.1~0.15MPa, and set the drying time to 10h. After drying, the moisture content of PPS should be ≤0.006%. Place the dried raw material in a sealed container and seal it for later use.

[0041] Multi-walled carbon nanotubes and sodium polyacrylate were dried separately using a vacuum oven. The drying temperature was set to 80℃, the vacuum degree inside the drum was maintained at -0.1 to 0.15 MPa, and the drying time was set to 12 hours. After drying, the moisture content of the raw materials should be ≤0.006%. The dried raw materials were then placed in a sealed container and sealed for later use.

[0042] (2) The twin-screw extruder is configured with ten zones. Zone 1 has a main feed port and an auxiliary feed port 1, where dried PPS and MWCNT are added respectively. Zone 2 utilizes a large-lead screw element for heating and conveying. Zone 3 has a feed port 2, where PAAS is added. After the material is fully melted in zones 4 and 5, two pressure-building zones are set up in zones 6 and 7 using a reverse screw element. These zones are equipped with triangular kneading elements and pin-type mixing elements to increase shear stress and enhance interaction. Zone 8 uses toothed kneading elements for kneading. Zone 9 is the melt homogenization zone, and zone 10 is the die head zone. Pressure sensors are installed in zones 6 and 10 to detect melt pressure. The melt pressure in both zones 6 and 10 is controlled between 7 and 8.5 MPa.

[0043] The temperature configuration of each zone of the twin-screw extruder is as follows: Zone 1 270℃±5℃, Zone 2 282℃±5℃, Zone 3 285℃±5℃, Zone 4 287℃±5℃, Zone 5 289℃±5℃; Zone 6 291℃±5℃, Zone 7 294℃±5℃, Zone 8 295℃±5℃, Zone 9 300℃±5℃, and the die head zone 302℃±5℃.

[0044] (3) After the melt is extruded through the die head, it enters the bend tube, then the metering pump, and after precise metering, it enters the spinning box. The bend tube, metering pump and box are set to a temperature of 300℃±5℃. The melt enters the spinning assembly in the box, is extruded through the spinneret to form a fine melt stream, and is then cooled and shaped by the ring blower. The fiber is stretched in two stages using 3 hot plates and 2 hot boxes. The temperature of the first hot plate is 90℃±1℃, the temperature of the second hot plate is 92℃±2℃, the temperature of the third hot plate is 92℃±2℃, the temperature of the first hot box is 110℃±2℃, and the temperature of the second hot box is 112℃±2℃. The total stretching ratio is 3 times. The stretching zone is configured as a small zone in the first zone and a large zone in the second zone. After stretching is completed, the hydrophilic conductive polyphenylene sulfide fiber is obtained by winding.

[0045] The morphology, hydrophilicity, and conductivity of the prepared hydrophilic conductive polyphenylene sulfide fibers were detected and analyzed.

[0046] The cross-sectional morphology of modified polyphenylene sulfide (PPS) fibers was obtained using a JSM-6700F scanning electron microscope. The test samples underwent surface sputtering with gold, and the accelerating voltage was set to 15 kV. The surface scan of the fiber cross-section using energy dispersive spectroscopy (EDS) on the scanning electron microscope was performed, and the resulting SEM-EDS images are shown below. Figure 1 The MWCNTs in the fiber showed good dispersion and no interfacial separation with the PPS matrix, indicating good compatibility. At the same time, the uniform distribution of Na elements around the MWCNTs indicated that PAAS and MWCNTs formed a complex relationship, which is conducive to the uniform dispersion of MWCNTs.

[0047] Surface contact angle was tested using a JC2000C1 contact angle meter at an ambient temperature of 20℃ and a relative humidity of 65%. 0.8 μL of water was dropped onto the sample surface, and the water contact angle was recorded. This was repeated 10 times, and the average value was taken. Figure 2 It can be seen that when the mass fraction of MWCNT is 3.5% (i.e., the mass percentage of MWCNT in MWCNT+PPS+PAAS), the hydrophilicity of the modified polyphenylene sulfide fiber gradually increases with the increase of the mass fraction of PAAS, reaching 43.5°.

[0048] Fiber volume resistivity testing: Fiber conditioning and testing were conducted according to GB6529 standard, with a temperature of 20±2℃ and a relative humidity of 62%–68%. Using a YG321 fiber resistivity meter, the test was performed according to GB / T 14342-93 standard. Each time, 15g of fiber that had reached moisture equilibrium (with a mass change of no more than 0.1% every half hour) was taken for resistivity measurement, repeated three times. The average value was used to obtain the fiber's volume resistivity. The reciprocal of the obtained volume resistivity was used to obtain the fiber's conductivity. Figure 3 It can be seen that when the mass fraction of PAAS is 1% (i.e., the mass percentage of PAAS in MWCNT+PPS+PAAS), the conductivity of the modified polyphenylene sulfide fiber increases with the increase of the mass fraction of MWCNT. The conductivity increases from 2.98 × 10⁻⁶ for the original pure PPS fiber. -13 The S / cm ratio can be increased to a maximum of 1.15 × 10⁻⁶ for modified fibers. -2 S / cm, an improvement of 11 orders of magnitude.

[0049] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing hydrophilic conductive polyphenylene sulfide fiber, characterized in that, Conductive additives, hydrophilic additives and polyphenylene sulfide resin are melt-blended using a twin-screw extruder, and then spun to obtain the hydrophilic conductive polyphenylene sulfide fiber; The twin-screw extruder is configured with ten zones. Zone 1 has a main feed port and an auxiliary feed port 1, where polyphenylene sulfide resin and conductive additives are added. Zone 2 uses a large-lead screw element for heating and conveying. Zone 3 has a feed port 2, where hydrophilic additives are added. After the material is fully melted in zones 4 and 5, two pressure-building zones are set in zones 6 and 7 using a reverse screw element. The pressure-building zones are equipped with triangular kneading elements and pin-type mixing elements to increase shear stress and enhance interaction. Zone 8 is equipped with toothed kneading elements for kneading. Zone 9 is for homogenization. Zone 10 is for extrusion. The conductive additive is multi-walled carbon nanotubes; the hydrophilic additive is sodium polyacrylate; the multi-walled carbon nanotubes account for 2.5-4% of the total mass of polyphenylene sulfide resin, multi-walled carbon nanotubes and sodium polyacrylate; the sodium polyacrylate accounts for 0.1-1.5% of the total mass of polyphenylene sulfide resin, multi-walled carbon nanotubes and sodium polyacrylate; the multi-walled carbon nanotubes are multi-walled carbon nanotubes that have undergone surface amination treatment. The temperature configuration of each zone of the twin-screw extruder is as follows: Zone 1 270℃±5℃, Zone 2 282℃±5℃, Zone 3 285℃±5℃, Zone 4 287℃±5℃, Zone 5 289℃±5℃; Zone 6 291℃±5℃, Zone 7 294℃±5℃, Zone 8 295℃±5℃, Zone 9 300℃±5℃, Zone 10 302℃±5℃; The melt pressure in zones six and ten is 7–8.5 MPa; The spinning process specifically involves: after melt blending, the melt is extruded through ten zones into a curved tube, then enters a metering pump, and after precise metering, enters a spinning box. Inside the box, it enters a spinning assembly, is extruded through a spinneret to form a fine melt stream, and is then cooled and shaped. The fiber is stretched in two stages using three hot plates and two hot boxes. The temperature of the first hot plate is 90℃±1℃, the temperature of the second hot plate is 92℃±2℃, the temperature of the third hot plate is 92℃±2℃, the temperature of the first hot box is 110℃±2℃, and the temperature of the second hot box is 112℃±2℃. The total stretching ratio is 3 to 5 times, and the stretching zones are configured as a small zone in the first zone and a large zone in the second zone.

2. The method for preparing hydrophilic conductive polyphenylene sulfide fiber according to claim 1, characterized in that, The set temperature for the bend, metering pump, and housing is 300℃±5℃.

3. A hydrophilic conductive polyphenylene sulfide fiber prepared by the preparation method according to any one of claims 1-2.

4. A hydrophilic conductive polyphenylene sulfide fiber fabric type alkaline water electrolysis diaphragm, characterized in that, It is obtained by weaving the hydrophilic conductive polyphenylene sulfide fiber as described in claim 3.

5. The application of the hydrophilic conductive polyphenylene sulfide fiber fabric type alkaline water electrolysis membrane according to claim 4 in the electrolysis of water to produce hydrogen.

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