Polyvinylidene fluoride-based nanofiber yarn wave-absorbing fabric as well as preparation method and application thereof

Abstract

The invention provides a polyvinylidene fluoride-based nanofiber yarn wave-absorbing fabric as well as a preparation method and application thereof, and belongs to the technical field of preparation of wave-absorbing composite materials. The preparation method comprises the following steps: preparing nanofiber yarns or nanofiber core-spun yarns by adopting a conjugate electrostatic spinning technology, directly adding a conductive substance into a spinning solution to form conductive nanofibers, and further coating the nanofiber yarns or the nanofiber core-spun yarns with a PDA shell layer to improve the wear resistance and reduce silver nanoparticles in situ; finally, the yarns are woven into fabric through a weaving or knitting technology, and the fabric is applied to the fields of buildings, electromagnetic protective clothing, flexible electronics and the like. Compared with an existing microwave absorbing material, the fabric-based material is light in weight and good in mechanical flexibility and processability. Fabrics formed of nanofiber yarns or nanofiber core spun yarns facilitate the induction of interfacial polarization and multiple reflections, and can deeply design material properties. The material provided by the invention has better wear resistance, wearability and microwave absorption performance, and is suitable for actual production and application.

Description

Technical Field

[0001] The invention relates to a polyvinylidene fluoride-based nanofiber yarn absorbing fabric, a preparation method and application thereof, and belongs to the technical field of preparation of absorbing composite materials. Background Art

[0002] The booming development of electronic devices such as flexible displays, integrated circuits, and foldable electronic paper has brought convenience, entertainment, and fashion to people. However, the electromagnetic interference generated by these devices not only interferes with adjacent components, but also threatens human health.

[0003] In recent years, the development of high-performance electromagnetic interference shielding materials has received great attention. In addition to high electromagnetic interference shielding effectiveness, mechanical flexibility is also crucial for shielding materials, especially in the fields of aircraft, aerospace, automobiles and next-generation flexible electronics. Fabric-based microwave absorbing materials are lightweight, have good mechanical flexibility and processability, and have become candidate materials for electromagnetic interference shielding with great application prospects. At present, most of these materials use a layer of microwave absorbing coating coated on the fabric substrate. The surface coating is prone to peeling or cracking under mechanical effects such as cleaning, friction, and bending, which ultimately affects the microwave absorption function. In addition, the outer coating of the fabric will affect the wearing performance of the fabric, resulting in poor drape, breathability, hygroscopicity, and comfort of the fabric.

[0004] Therefore, there is an urgent need in the art for a fabric-based microwave absorbing material with excellent wearing performance and greater durability. Summary of the invention

[0005] The purpose of the present invention is to solve the problems of poor wearing performance and insufficient durability of fabric-based microwave absorbing materials in practical applications in the prior art.

[0006] In order to achieve the purpose of solving the above-mentioned problems, the technical solution adopted by the present invention is to provide a polyvinylidene fluoride (PVDF) based nanofiber yarn absorbing fabric, and its preparation method and application.

[0007] In a first aspect of the present invention, a method for preparing a polyvinylidene fluoride based nanofiber yarn absorbing fabric is provided, comprising the following steps:

[0008] Step 1: Dissolve PVDF in a solvent at room temperature and stir in a water bath to obtain a mixed solution;

[0009] Step 2: dissolving the conductive material in the mixed solution prepared in step 1, stirring and ultrasonicating in a water bath to obtain a homogeneous spinning solution;

[0010] Step 3: Prepare nanofiber yarn or nanofiber core-spun yarn by a conjugate electrospinning method using the spinning solution obtained in step 2, and put it into an oven for drying;

[0011] Step 4: placing the nanofiber yarn or nanofiber core-spun yarn obtained in step 3 in a mixed solution of dopamine hydrochloride and Tris-HCl buffer solution, self-polymerizing a polydopamine (PDA) shell layer on the yarn surface, and placing it in an oven to dry;

[0012] Step 5: placing the yarn obtained in step 4 in a silver ammonia solution prepared by mixing silver nitrate and ammonia solution, and reducing silver nanoparticles on the surface of the yarn by relying on the reducing property of PDA;

[0013] Step 6: Weave the yarn or core-spun yarn obtained in step 5 into a fabric to obtain a PVDF-based nanofiber yarn absorbing fabric.

[0014] Preferably, in step 1, the molecular weight of PVDF is 50w-200w, the solvent is DMF, acetone or a mixed solution of DMF and acetone, the mass fraction of PVDF is 5%-30%, and the water bath temperature is 60°C-80°C.

[0015] Preferably, in step 2, the conductive material is carbon black, graphene, carbon nanotubes, or MXene, and the mass of the conductive material is 0.01 g to 0.4 g.

[0016] Preferably, in step 3, the voltage of conjugate electrospinning is 6 to 15 kV, the propulsion speed is 0.5 to 1.2 ml / h, the receiving distance is 8 to 12 cm, the collecting device is a rotor collection, the rotor speed is 30 to 50 r / min, and the collecting roller collection speed is 0.1 r / min to 1 r / min; the nanofiber core-spun yarn is cotton yarn, polyester yarn, nylon yarn, carbon fiber bundle or polyurethane fiber prepared by wet spinning.

[0017] Preferably, in step 4, the concentration of dopamine hydrochloride solution is 0.5 mg / ml to 30 mg / ml, the concentration of Tris-HCl buffer solution is 0.01 M to 1 M, the volume of Tris-HCl buffer solution is 1 ml to 100 ml, and the self-polymerization time is 6 h to 72 h.

[0018] Preferably, in step 5, the concentration of the silver nitrate solution is 1 mg / ml to 50 mg / ml, the concentration of the ammonia solution is 5% to 26%, and the reduction time is 5 min to 120 min.

[0019] Preferably, in step 6, the weaving form is woven or knitted, the warp density is more than 250 yarns / 10 cm, the weft density is more than 100 yarns / 10 cm, the transverse density is more than 100 yarns / 5 cm, and the longitudinal density is more than 30 yarns / 5 cm.

[0020] Preferably, in step 6, when the weaving form is machine weaving, the warp yarns are selected including but not limited to cotton yarn, polyester yarn, PVDF-based nanofiber core-spun yarn, and the fabric structure is plain weave, satin weave, twill weave, or multi-layer weave.

[0021] Preferably, in step 6, when the weaving form is knitting, the fabric structure is a plain weft stitch structure, a rib structure or a double rib structure.

[0022] The second aspect of the present invention provides a PVDF-based nanofiber yarn absorbing fabric material obtained by the above method.

[0023] The third aspect of the present invention provides an application of the above-mentioned PVDF-based nanofiber yarn absorbing fabric material in the fields of construction, electromagnetic protective clothing, and flexible electronics.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention provides a method of producing nanofiber yarn or nanofiber core-spun yarn by electrospinning technology and assembling it into a fabric. The fabric has adjustable density, a wide selection of warp yarn and core yarn, and good strength and microwave absorption function. At the same time, the preparation process is simple, convenient and green, suitable for large-scale production and application, and has potential application value in the fields of construction, electromagnetic protective clothing, flexible electronics, etc.

[0026] 2. The present invention utilizes electrospinning technology, so that the core-spun yarn produced by the present invention can have the advantages of electrospinning, such as obtaining a fiber structure with adjustable diameter, simple preparation, continuous and efficient spinning, high fiber purity, good uniformity, and multiple reflections induced by more interfaces. The internal conductive material can form a conductive network, reduce the percolation threshold of the PVDF nanofiber yarn, and enhance its conductive loss.

[0027] 3. In the present invention, materials such as polyvinylidene fluoride, conductive materials, polydopamine, and silver nitrate are selected. Among them, polyvinylidene fluoride has the advantages of high mechanical strength and toughness, high wear resistance, good heat stability, flame retardancy, resistance to most chemicals and solvents, and both rigid and flexible forms, which are very suitable as the matrix material of the yarn. Moreover, the conjugated electrospinning technology and the addition of conductive materials can promote the transformation of polyvinylidene fluoride from the α phase to the β phase, enhance the dielectric properties of the polyvinylidene fluoride matrix, and help improve the microwave absorption performance. In order to further improve the performance of the yarn, by coating a layer of polydopamine on the surface and reducing silver nanoparticles, the conductivity and interface of the material are increased, and the conductive loss and polarization loss are enhanced. The PDA shell can effectively enhance the wear resistance of nanofiber yarn or nanofiber core-spun yarn, and the silver nanoparticles on the surface have a strong inhibitory and killing effect on pathogenic microorganisms such as Escherichia coli and Chlamydia trachomatis, and have good antibacterial function.

[0028] 4. The yarn prepared by the present invention can realize the deep design of fabric-based microwave absorbing materials. Different from the traditional coating method, the present method makes the fabric have better durability and wearing performance, such as air permeability, moisture permeability, hygroscopicity, etc. In order to improve the microwave absorption performance, the fabric is made tighter, and larger warp density, weft density, transverse density and longitudinal density are selected. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the prepared PVDF-based nanofiber yarn, a is coreless yarn, and b is core-spun yarn.

[0030] Figure 2 Schematic diagram of the prepared PVDF-based nanofiber woven fabric.

[0031] Figure 3 This is a physical picture of the prepared PVDF-based nanofiber yarn and fabric (Example 1), a is the yarn, and b is the fabric.

[0032] Figure 4 This is a scanning electron microscope image of the prepared PVDF-based nanofiber yarn (Example 1), a is the image of CNT@PVDF nanofiber yarn at 70 times, b is the image of CNT@PVDF nanofiber yarn at 40,000 times, c is the image of CNT@PVDF@PDA@Ag nanofiber yarn at 60,000 times, and d is the image of CNT@PVDF@PDA@Ag nanofiber yarn at 1,000,000 times.

[0033] Figure 5 This is a transmission electron microscope image of the prepared CNT@PVDF nanofibers (Example 1).

[0034] Figure 6 This is a scanning electron microscope image of the cross section of the carbon fiber bundle @CNTs@PVDF core-spun yarn (Example 3).

[0035] Figure 7 These are reflection loss images of the polyvinylidene fluoride-based nanofiber yarn absorbing fabric prepared in Example 1 in different frequency bands.

[0036] Figure 8 This is the reflection loss image of the polyvinylidene fluoride based nanofiber yarn absorbing fabric prepared in Example 2 in different frequency bands.

[0037] Fig. 9 This is the reflection loss image of the polyvinylidene fluoride based nanofiber yarn absorbing fabric prepared in Example 3 in different frequency bands. DETAILED DESCRIPTION

[0038] In order to make the present invention more clearly understood, a preferred embodiment is described in detail with reference to the accompanying drawings as follows:

[0039] Embodiment 1

[0040] (1) At room temperature, 1.2 g of polyvinylidene fluoride (PVDF) powder was dissolved in 8.8 g of N,N-dimethylformamide (DMF) and stirred in a 70°C water bath for 4 h to obtain a PVDF / DMF solution.

[0041] (2) 0.12 g of carbon nanotubes (CNT) was dissolved in the PVDF / DMF solution prepared above, stirred in a water bath for 6 h and ultrasonicated for 1 h to obtain a homogeneous spinning solution.

[0042] (3) The spinning solution obtained in (2) was used to prepare CNT@PVDF nanofiber yarn by an electrospinning method. The voltage applied by syringe No. 1 was 7.2 kv, the propulsion speed was 1 ml / h, and the receiving distance was 10 cm. The voltage applied by syringe No. 2 was -7.2 kv, the propulsion speed was 1 ml / h, the receiving distance was 10 cm, the rotor speed was 28 r / min, the relative humidity was 58%, the temperature was 28°C, and it was placed in an oven and dried at 50°C for 24 h.

[0043] (4) The yarn obtained in (3) is placed in a mixed solution of dopamine hydrochloride and Tris-HCl buffer solution for a certain period of time, and a polydopamine (PDA) shell is self-polymerized on the surface of the yarn. The concentration of dopamine hydrochloride solution is 10 mg / ml, the volume of dopamine hydrochloride solution is 10 ml, the concentration of Tris-HCl buffer solution is 0.1 M, the volume of the solution is 10 ml, the pH is 8.5, the polymerization time is 60 h, and the yarn is placed in an oven and dried at 50°C for 24 h.

[0044] (5) The yarn obtained in (4) was placed in a silver ammonia solution prepared by mixing silver nitrate (AgNO3) and ammonia water (NH3·H2O) solutions. Relying on the reducing property of PDA, silver nanoparticles were reduced on the surface of the yarn. The concentration of the silver nitrate solution was 20 mg / ml, the volume of the silver nitrate solution was 30 ml, the concentration of the ammonia water solution was 26% to 28%, and the reduction time was 60 min, thereby obtaining CNT@PVDF@PDA@Ag NPs nanofiber yarn.

[0045] (6) The nanofiber yarn obtained in (5) is used as the weft yarn, the warp yarn is selected as cotton yarn, the weaving form is selected as woven, the warp yarn density is 275 yarns / 10cm, and the weft yarn density is 120 yarns / 10cm, so as to obtain the PVDF-based nanofiber yarn absorbing fabric. The minimum reflection loss (RL min ) is -41.14dB, and the maximum effective absorption bandwidth (EAB,RL<-10dB) is 1.44GHz. Figure 7 shown.

[0046] Embodiment 2

[0047] (1) At room temperature, 1.2 g of polyvinylidene fluoride (PVDF) powder was dissolved in 8.8 g of N,N-dimethylformamide (DMF) and stirred in a 70°C water bath for 4 h to obtain a PVDF / DMF solution.

[0048] (2) 0.096 g of carbon nanotubes (CNT) was dissolved in the PVDF / DMF solution prepared above, stirred in a water bath for 6 h and ultrasonicated for 1 h to obtain a homogeneous spinning solution.

[0049] (3) The spinning solution obtained in (2) was used to prepare CNT@PVDF nanofiber yarn by an electrospinning method. The voltage applied by syringe No. 1 was 6.8 kv, the propulsion speed was 0.8 ml / h, and the receiving distance was 10 cm. The voltage applied by syringe No. 2 was -6.8 kv, the propulsion speed was 0.8 ml / h, the receiving distance was 10 cm, the rotor speed was 20 r / min, the relative humidity was 58%, the temperature was 28°C, and it was placed in an oven and dried at 50°C for 24 hours.

[0050] (4) The yarn obtained in (3) is placed in a mixed solution of dopamine hydrochloride and Tris-HCl buffer solution for a certain period of time, and a polydopamine (PDA) shell is self-polymerized on the surface of the yarn. The concentration of dopamine hydrochloride solution is 10 mg / ml, the volume of dopamine hydrochloride solution is 10 ml, the concentration of Tris-HCl buffer solution is 0.1 M, the volume of the solution is 10 ml, the pH is 8.5, the polymerization time is 60 h, and the yarn is placed in an oven and dried at 50°C for 24 h.

[0051] (5) The yarn obtained in (4) was placed in a silver ammonia solution prepared by mixing silver nitrate (AgNO3) and ammonia water (NH3·H2O) solutions. Relying on the reducing property of PDA, silver nanoparticles were reduced on the surface of the yarn. The concentration of the silver nitrate solution was 20 mg / ml, the volume of the silver nitrate solution was 30 ml, the concentration of the ammonia solution was 26% to 28%, and the reduction time was 60 min, thus obtaining CNT@PVDF@PDA@Ag NPs yarn.

[0052] (6) The nanofiber yarn obtained in (5) is used as the weft yarn, the warp yarn is selected as cotton yarn, the weaving form is selected as woven, the warp yarn density is 275 yarns / 10cm, and the weft yarn density is 123 yarns / 10cm, so as to obtain the PVDF-based nanofiber yarn absorbing fabric. The minimum reflection loss (RL min ) is -59.17dB, and the maximum effective absorption bandwidth (EAB,RL<-10dB) is 0.67GHz. Figure 8 shown.

[0053] Embodiment 3

[0054] (1) At room temperature, 1.2 g of polyvinylidene fluoride (PVDF) powder was dissolved in 8.8 g of N,N-dimethylformamide (DMF) and stirred in a 70°C water bath for 4 h to obtain a PVDF / DMF solution.

[0055] (2) 0.12 g of carbon nanotubes (CNT) was dissolved in the PVDF / DMF solution prepared above, stirred in a water bath for 6 h and ultrasonicated for 1 h to obtain a homogeneous spinning solution.

[0056] (3) The spinning solution obtained in (2) was used to prepare CNT@PVDF nanofiber yarn by an electrospinning method. The voltage applied by syringe No. 1 was 7.3 kV, the propulsion speed was 1 ml / h, and the receiving distance was 10 cm. The voltage applied by syringe No. 2 was -7.3 kV, the propulsion speed was 1 ml / h, the receiving distance was 10 cm, the rotor speed was 30 r / min, the relative humidity was 58%, the temperature was 28°C, and the core yarn was a carbon fiber bundle, which was placed in an oven and dried at 50°C for 24 h to obtain a carbon fiber bundle@CNT@PVDF core-spun yarn, such as Figure 6 shown.

[0057] (4) The core-spun yarn obtained in (3) is used as the weft yarn, the warp yarn is selected as cotton yarn, the weaving form is selected as woven, the warp yarn density is 276 yarns / 10cm, and the weft yarn density is 100 yarns / 10cm, so as to obtain the polyvinylidene fluoride based nanofiber core-spun yarn absorbing fabric. The minimum reflection loss (RL min ) is -47.7dB, and the maximum effective absorption bandwidth (EAB,RL<-10dB) is 0.44GHz. Fig. 9 shown.

[0058] Comparative Example 1

[0059] The untreated carbon fiber bundle was used as the weft yarn, the warp yarn was selected as cotton yarn, the weaving form was selected as woven, the warp yarn density was 272 yarns / 10cm, and the weft yarn density was 113 yarns / 10cm, and the absorbing fabric comparison sample was obtained. After the absorbing performance test, its minimum reflection loss (RL min ) is -17dB, and the maximum effective absorption bandwidth (EAB,RL<-10dB) is 2.84GHz.

[0060] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and equivalent changes made by using the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a polyvinylidene fluoride-based nanofiber yarn absorbing fabric, characterized in that: The following steps are involved: Step 1: Dissolve PVDF in a solvent at room temperature and stir in a water bath to obtain a mixed solution; Step 2: dissolving the conductive material in the mixed solution prepared in step 1, stirring and ultrasonicating in a water bath to obtain a homogeneous spinning solution; Step 3: Prepare nanofiber yarn or nanofiber core-spun yarn by a conjugate electrospinning method using the spinning solution obtained in step 2, and put it into an oven for drying; Step 4: placing the nanofiber yarn or nanofiber core-spun yarn obtained in step 3 in a mixed solution of dopamine hydrochloride and Tris-HCl buffer solution, self-polymerizing a polydopamine (PDA) shell layer on the yarn surface, and placing it in an oven to dry; Step 5: placing the yarn obtained in step 4 in a silver ammonia solution prepared by mixing silver nitrate and ammonia solution, and reducing silver nanoparticles on the surface of the yarn by relying on the reducing property of PDA; Step 6: Weave the yarn or core-spun yarn obtained in step 5 into a fabric to obtain a PVDF-based nanofiber yarn absorbing fabric.

2. The method for preparing the polyvinylidene fluoride-based nanofiber yarn absorbing fabric according to claim 1, characterized in that: In the step 1, the molecular weight of PVDF is 50w-200w, the solvent is DMF, acetone or a mixed solution of DMF and acetone, the mass fraction of PVDF is 5%-30%, and the water bath temperature is 60°C-80°C.

3. The method for preparing the polyvinylidene fluoride based nanofiber yarn absorbing fabric according to claim 1, characterized in that: In the step 2, the conductive material is carbon black, graphene, carbon nanotubes or MXene, and the mass of the conductive material is 0.01g to 0.4g.

4. The method for preparing the polyvinylidene fluoride-based nanofiber yarn absorbing fabric according to claim 1, characterized in that: In the step 3, the voltage of the conjugate electrospinning is 6 to 15 kV, the propulsion speed is 0.5 to 1.2 ml / h, the receiving distance is 8 to 12 cm, the collecting device is a rotor collection, the rotor speed is 30 to 50 r / min, and the collecting roller collection speed is 0.1 r / min to 1 r / min; the core yarn in the nanofiber core-spun yarn is cotton yarn, polyester yarn, nylon yarn, carbon fiber bundle or polyurethane fiber prepared by wet spinning.

5. The method for preparing the polyvinylidene fluoride-based nanofiber yarn absorbing fabric according to claim 1, characterized in that: In the step 4, the concentration of the dopamine hydrochloride solution is 0.5 mg / ml to 30 mg / ml, the concentration of the Tris-HCl buffer solution is 0.01 M to 1 M, the volume of the Tris-HCl buffer solution is 1 ml to 100 ml, and the self-polymerization time is 6 h to 72 h.

6. The method for preparing the polyvinylidene fluoride-based nanofiber yarn absorbing fabric according to claim 1, characterized in that: In the step 5, the concentration of the silver nitrate solution is 1 mg / ml to 50 mg / ml, the concentration of the ammonia solution is 5% to 26%, and the reduction time is 5 min to 120 min.

7. The method for preparing the polyvinylidene fluoride-based nanofiber yarn absorbing fabric according to claim 1, characterized in that: In the step 6, the weaving form is woven or knitted, the warp density is more than 250 yarns / 10 cm, the weft density is more than 100 yarns / 10 cm, the transverse density is more than 100 yarns / 5 cm, and the longitudinal density is more than 30 yarns / 5 cm.

8. The method for preparing the polyvinylidene fluoride-based nanofiber yarn absorbing fabric according to claim 7, characterized in that: In the step 6, when the weaving form is weaving, the warp yarn is cotton yarn, polyester yarn or polyvinylidene fluoride-based nanofiber core-spun yarn, and the fabric structure is plain weave, satin weave, twill weave or multi-layer weave; when the weaving form is knitting, the fabric structure is weft plain weave, rib weave or double rib weave.

9. A polyvinylidene fluoride-based nanofiber yarn absorbing fabric material obtained by the preparation method according to any one of claims 1 to 8.

10. An application of the polyvinylidene fluoride-based nanofiber yarn absorbing fabric material as claimed in claim 9 in the fields of construction, electromagnetic protective clothing, and flexible electronics.

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