Preparation method of magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper

Abstract

The invention provides a magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper preparation method, which comprises: adding an aniline monomer and magnetic nanoparticles to a carbon fiber suspension, dropwise adding a hydrochloric acid solution, uniformly dispersing, and maintaining in an ice-water bath to obtain a mixed solution; dissolving ammonium persulfate in pre-cooled deionized water, then adding into the mixed solution, polymerizing for 5-15 hours, and washing to obtain surface modified carbon fiber of the magnetic nanoparticle / polyaniline modified carbon fiber; the surface modified carbon fibers and the plant fibers with the mass ratio of 1: 9-9: 1 are taken and mixed in water, a fiber suspension is obtained, after defibering is conducted through a pulp defibering machine, wet forming is conducted on a paper sample beater to obtain a wet paper web, and after pressing is conducted for 1-10 min under the pressure of 5-10 MPa, drying is conducted to obtain the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper. The method has the advantages of simplicity, convenience, low cost and the like, and has a relatively good application prospect in carbon fiber composite materials.

Description

Technical Field

[0001] The invention relates to the technical field of surface and interface modification of conductive polymer / inorganic fiber doped with magnetic nanoparticles, and in particular to a method for preparing magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper. Background Art

[0002] As an emerging material, carbon fiber has become an indispensable strategic high-performance new material in today's world with excellent properties such as light weight, high and low temperature resistance, electrical conductivity, corrosion resistance, fatigue resistance, creep resistance, heat conductivity and low thermal expansion coefficient. Carbon fiber composites have most of the physical requirements required for the application of electromagnetic shielding materials. However, when carbon fiber is used alone as an absorbing and shielding material, it may have defects such as low magnetic permeability, high dielectric constant, low absorption intensity and narrow absorption band. When carbon fiber is composited with some conductive, dielectric and magnetic functional particles to prepare composite materials, it can not only give full play to the excellent electromagnetic shielding performance of carbon fiber, but also overcome the shortcomings of poor performance when carbon fiber is used alone. In a paper published in Nanomaterials, Vol. 9, No. 3, 460 in 2019, Jiao et al. proposed a core-shell composite material composed of cotton-based carbon fiber (CDCF) and nano copper. Cotton fiber is pyrolyzed into conductive and hydrophobic CDCF, and a layer of nano copper is deposited on the surface of CDCF. The synergistic effect of nano copper and CDCF composite material makes the electromagnetic shielding effectiveness reach 29.3 dB. Wang et al., in a paper published in Polymer Composites, Vol. 44, No. 12, pp. 8838-8848 in 2023, proposed the use of nickel-plated (Ni-CF) fabrics to enhance the electromagnetic interference shielding capability of carbon fiber reinforced thermoplastics (CFRT), which is particularly suitable for automotive and aerospace applications. Ni-CF reinforced polyamide 6 (Ni-CF / PA 6) was prepared by a laminated film method. The introduction of the nickel layer significantly improved the EMI shielding efficiency of the CF / PA 6 composite material, and the average shielding efficiency in the X-band and Ku-band frequency ranges increased from 23.5 dB to 31.6 dB. Zhang et al., in a paper published in Polymer Composites, Vol. 16, No. 2, pp. 608 in 2023, proposed the use of a free arc diffused surface spraying process to prepare a sandwich structure composite material CF@(carbon nanotube / Fe3O4) / epoxy resin (CF@(CNT / Fe3O4) / EP), in which CFs was used as the middle layer, (CNT / Fe3O4) and EP were used as the top and substrate layers. By consuming a small amount of CNT / Fe3O4, (CNT / Fe3O4) / EP and CFs core sheath achieve thermal and electrical anisotropy and directional enhancement, and better enhance electromagnetic interference shielding performance through multiple absorption-reflection / penetration-reabsorption. At present, the work on carbon fiber modification to prepare electromagnetic shielding materials has achieved good results, but the processing process has problems such as cumbersome, low yield, high cost, and difficulty in implementation.

[0003] Electromagnetic shielding mechanisms are divided into reflection and absorption; reflection can be achieved with the help of the charge carriers of the material, so the material should be conductive; absorption is caused by the interaction between the electric dipole or magnetic dipole of the material and the incident radiation; the electric dipole or magnetic dipole required for absorption can be provided by materials with high dielectric constant and magnetic permeability; conductive polymers have received extensive attention as electromagnetic interference shielding materials, among which polyaniline has another amorphous structure to increase the electromagnetic wave absorption performance in addition to its good conductivity to absorb electromagnetic waves. Metal and polyaniline-based compositions have attracted attention due to their conductivity, adjustable dielectric constant or magnetic permeability, nominal cost and good stability. In a paper published in 2020 in Composites Science and Technology, Vol. 188, 107991, Pen et al. proposed the use of artificial suede cloth (ASC) fabric as the substrate, and successfully prepared ASC fabric coated with mulberry-like polyaniline clusters by a simple in-situ polymerization technique. A three-dimensional sandwich-like polyaniline conductive network was established on the surface of ASC. Due to the unique heterogeneous structure, the electromagnetic shielding performance of ASC / polyaniline fabric reaches 25.90 dB. Ferrite / iron-nickel alloy and its composite materials with conductive polymers have low cost, low density, high stability, saturation magnetization, magnetic permeability, resistivity, dielectric constant, good magnetic properties and corrosion resistance, and are good fillers for electromagnetic shielding materials. In a paper published in Journal of Alloys and Compounds, Vol. 862, 158331 in 2021, Kumar et al. proposed the preparation of ferrite-polyaniline composites by in situ polymerization. By adding 50% by weight of ferrite nanoparticles to polyaniline, a shielding effect of 60 dB was obtained, indicating that the composite material has high magnetic permeability and high magnetic / electric loss, and can attenuate more than 99.9% of the incident electromagnetic radiation. However, how to make full use of the above technology in the preparation of composite paper has become an urgent problem to be solved. Summary of the invention

[0004] The present invention uses high-strength carbon fiber as a matrix, and after surface modification by magnetic nanoparticles / polyaniline, obtains surface-modified carbon fiber with good dielectric properties. The modified carbon fiber is then compounded with plant fiber to prepare composite paper, thereby obtaining composite paper with excellent electromagnetic shielding properties.

[0005] In order to solve the above technical problems, the technical solutions provided by the present invention are as follows: The method for preparing magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper comprises the following steps: Aniline monomer and magnetic nanoparticles are added to the carbon fiber suspension, and then a hydrochloric acid solution is added dropwise and dispersed uniformly, and then kept in an ice water bath to obtain a mixed solution; Ammonium persulfate is first dissolved in precooled deionized water, then added to the above mixed solution for polymerization for 5-15 hours, and then washed to obtain surface-modified carbon fibers of magnetic nanoparticles / polyaniline-modified carbon fibers; The surface-modified carbon fiber and plant fiber are mixed in a mass ratio of 1:9-9:1 in water to obtain a fiber suspension, and after being deflated by a pulp deflagrator, wet-formed on a paper sample copyer to obtain a wet paper web, which is pressed at a pressure of 5 MPa-10 MPa for 1-10 min, and then dried to obtain a magnetic nanoparticle / polyaniline surface-modified carbon fiber composite paper.

[0006] Furthermore, the mass ratio of the aniline monomer to the carbon fibers in the carbon fiber suspension is 1:10-1:1, and the mass ratio of the magnetic nanoparticles to the aniline monomer is 1:10-1:1.

[0007] Furthermore, when the hydrochloric acid solution is added dropwise, the hydrochloric acid solution is 0.5%-2.5% of the mixed solution.

[0008] Furthermore, the magnetic nanoparticles include nano-Fe 3 O 4 、Nano-FeNi 3 Or sheet-like nano-FeNi 3 One of the iron-based nanoparticles.

[0009] Furthermore, the mass ratio of ammonium persulfate to aniline is 1:5 to 5:1.

[0010] Furthermore, the deflaking speed in the deflaking machine is 5000-50000 revolutions.

[0011] Furthermore, the plant fiber is coniferous wood fiber, hardwood fiber, bamboo pulp fiber or straw pulp fiber.

[0012] Furthermore, the beating degree of the plant fiber is 30°SR~60°SR.

[0013] The present invention has the following beneficial effects: The present invention uses magnetic nanoparticles and aniline monomers to modify carbon fibers, generate a polyaniline / magnetic nanoparticle layer on the surface of the carbon fibers, and then compound with plant fibers to prepare composite paper. By giving full play to the respective advantages of plant fibers, carbon fibers, magnetic nanoparticles and polyaniline, it is expected to achieve an increase in the dielectric loss and magnetic loss of the composite material, which is of great significance for the development of the next generation of low-density, strong absorption carbon fiber electromagnetic shielding materials.

[0014] The surface modified carbon fiber obtained by the present invention is used as a reinforcement to enhance the mechanical properties of paper, improve the dielectric loss and magnetic loss of composite paper, so that the composite paper has excellent electromagnetic interference shielding performance and mechanical properties. The experimental conditions of the present invention are easy to implement, the method is simple, the cost is low, and the invention has good application prospects in carbon fiber composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a scanning electron microscope image of the modified carbon fiber in Example 1 provided by the present invention; Figure 2 This is a scanning electron microscope image of the modified carbon fiber in Example 2 provided by the present invention; Figure 3 This is a scanning electron microscope image of the modified carbon fiber in Example 3 provided by the present invention. DETAILED DESCRIPTION

[0016] The present invention is described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0017] In the prior art, when carbon fiber is used alone as a shielding material, it may face some performance limitations, such as insufficient magnetic permeability, high dielectric constant, etc. In order to solve the above technical problems, a method of surface-modified carbon fiber composite paper with magnetic nanoparticles / polyaniline is proposed in this embodiment.

[0018] The preparation method in this embodiment specifically comprises the following steps: (1) Preparation of magnetic nanoparticle / polyaniline surface modified carbon fibers: An appropriate amount of carbon fiber is dispersed in deionized water to obtain a carbon fiber suspension with a weight percentage of 0.5% to 2%, and an appropriate amount of aniline monomer and magnetic nanoparticles are added, wherein the mass ratio of aniline monomer to carbon fiber is 1:10 to 1:1, and the mass ratio of magnetic nanoparticles to aniline monomer is 1:10 to 1:1. Subsequently, a 37% hydrochloric acid solution with a total mass weight percentage of 0.5% to 2.5% of the above mixed solution is added dropwise, and after uniform dispersion, it is kept in an ice water bath for 1 to 5 hours. Then, an appropriate amount of ammonium persulfate is dissolved in pre-cooled deionized water, and then slowly added to the mixed solution for polymerization for 5 to 15 hours, and the product is washed and dried to obtain magnetic nanoparticle / polyaniline modified carbon fiber.

[0019] In this embodiment, magnetic nanoparticles include but are not limited to nano-Fe 3 O 4 、Nano-FeNi 3 and flake nano-FeNi3 of iron-based nanoparticles.

[0020] (2) Preparation of magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper: The surface modified carbon fiber and plant fiber obtained in step 1 are mixed in water at a ratio of 1:9 to 9:1 to obtain a fiber suspension with a concentration of 0.002 g / mL to 0.2 g / mL, which is placed in a pulp disintegrator for 5000 to 50000 revolutions, and then wet-formed on a paper sampler to obtain a wet paper web, which is pressed at a pressure of 5 MPa to 10 MPa for 1 to 10 min. Subsequently, the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper is obtained by drying.

[0021] The plant fiber at this time includes but is not limited to one of softwood fiber, hardwood fiber, bamboo pulp fiber or straw pulp fiber or a mixture thereof.

[0022] In this embodiment, the carbon fiber is modified with magnetic nanoparticles and aniline monomers to generate a polyaniline / magnetic nanoparticle layer on the surface of the carbon fiber, which is then compounded with plant fibers to prepare composite paper. The advantages of plant fibers, carbon fibers, magnetic nanoparticles and polyaniline are fully utilized to improve the dielectric loss and magnetic loss of the composite material, which is of great significance for the development of the next generation of low-density, strong absorption carbon fiber electromagnetic shielding materials.

[0023] The specific embodiments in this embodiment are as follows: Example

[0024] Step 1: Preparation of magnetic nanoparticle / polyaniline surface modified carbon fibers: Disperse an appropriate amount of carbon fiber in deionized water to obtain a carbon fiber suspension with a weight percentage of 0.7%, add an appropriate amount of aniline monomer and magnetic nanoparticles, wherein the mass ratio of aniline monomer to carbon fiber is 1:3, and the mass ratio of magnetic nanoparticles to aniline monomer is 1:4. Then, add 0.8% of the total mass of the mixed solution, 37% hydrochloric acid solution, and keep it in an ice water bath for 2 hours after uniform dispersion. Then dissolve ammonium persulfate with a mass ratio of 2:1 to aniline in pre-cooled deionized water and then slowly add it to the mixed solution. After polymerization for 6 hours, wash and dry the product to obtain magnetic nanoparticle / polyaniline modified carbon fiber.

[0025] Step 2: Preparation of magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper: The surface modified carbon fiber obtained in step 1 and the softwood fiber with a beating degree of 35 °SR were mixed in water at a ratio of 2:8 to obtain a fiber suspension with a concentration of 0.09 g / mL, which was placed in a pulp disintegrator for 9000 revolutions, and then wet-formed on a paper sampler to obtain a wet paper web, which was pressed at a pressure of 6 MPa for 5 min. Subsequently, the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper was obtained by drying.

[0026] Compared with unmodified carbon fiber / plant fiber paper, the dielectric loss tangent, magnetic loss tangent and electromagnetic interference shielding performance of the composite material are significantly improved. (Related data see Table 1) Example

[0027] Step 1: Preparation of magnetic nanoparticle / polyaniline surface modified carbon fibers: Disperse an appropriate amount of carbon fiber in deionized water to obtain a carbon fiber suspension with a weight percentage of 0.5%, add an appropriate amount of aniline monomer and magnetic nanoparticles, wherein the mass ratio of aniline monomer to carbon fiber is 1:6, and the mass ratio of magnetic nanoparticles to aniline monomer is 1:3. Then, add 2.0% of the total mass of the mixed solution, 37% hydrochloric acid solution, and keep it in an ice water bath for 2.5 hours after uniform dispersion. Then dissolve ammonium persulfate with a mass ratio of 7:1 to aniline in pre-cooled deionized water and then slowly add it to the mixed solution. After polymerization for 8 hours, wash and dry the product to obtain magnetic nanoparticle / polyaniline modified carbon fiber.

[0028] Step 2: Preparation of magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper: The surface modified carbon fiber obtained in step 1 and the hardwood fiber with a beating degree of 37 °SR were mixed in water at a ratio of 3:7 to obtain a fiber suspension with a concentration of 0.11 g / mL, which was placed in a pulp disintegrator for 10,000 revolutions, and then wet-formed on a paper sampler to obtain a wet paper web, which was pressed at a pressure of 3 MPa for 7 min. Subsequently, the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper was obtained by drying.

[0029] Compared with unmodified carbon fiber / plant fiber paper, the dielectric loss tangent, magnetic loss tangent and electromagnetic interference shielding performance of the composite material are significantly improved. (Related data see Table 1) Example

[0030] Step 1: Preparation of magnetic nanoparticle / polyaniline surface modified carbon fibers: Disperse an appropriate amount of carbon fiber in deionized water to obtain a carbon fiber suspension with a weight percentage of 1.2%, add an appropriate amount of aniline monomer and magnetic nanoparticles, wherein the mass ratio of aniline monomer to carbon fiber is 1:4, and the mass ratio of magnetic nanoparticles to aniline monomer is 1:5. Then, add 1.7% of the total mass of the mixed solution, 37% hydrochloric acid solution, and keep it in an ice water bath for 3 hours after uniform dispersion. Then dissolve ammonium persulfate with a mass ratio of 6:1 to aniline in pre-cooled deionized water and then slowly add it to the mixed solution. After polymerization for 9 hours, wash and dry the product to obtain magnetic nanoparticle / polyaniline modified carbon fiber.

[0031] Step 2: Preparation of magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper: The surface modified carbon fiber obtained in step 1 and the straw fiber with a beating degree of 40°SR were mixed in water at a ratio of 2:8 to obtain a fiber suspension with a concentration of 0.15 g / mL, which was placed in a pulp disintegrator for 20,000 revolutions, and then wet-formed on a paper sampler to obtain a wet paper web, which was pressed at a pressure of 8 MPa for 3 min. Subsequently, the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper was obtained by drying.

[0032] Compared with unmodified carbon fiber / plant fiber paper, the dielectric loss tangent, magnetic loss tangent and electromagnetic interference shielding performance of the composite material are significantly improved. (Related data see Table 1) Example

[0033] Step 1: Preparation of magnetic nanoparticle / polyaniline surface modified carbon fibers: Disperse an appropriate amount of carbon fiber in deionized water to obtain a carbon fiber suspension with a weight percentage of 1.5%, add an appropriate amount of aniline monomer and magnetic nanoparticles, wherein the mass ratio of aniline monomer to carbon fiber is 1:5, and the mass ratio of magnetic nanoparticles to aniline monomer is 1:7. Then, add 1.5% of the total mass of the mixed solution, 37% hydrochloric acid solution, and keep it in an ice water bath for 3.5 hours after uniform dispersion. Then dissolve ammonium persulfate with a mass ratio of 8:1 to aniline in pre-cooled deionized water and then slowly add it to the mixed solution. After polymerization for 12 hours, wash and dry the product to obtain magnetic nanoparticle / polyaniline modified carbon fiber.

[0034] Step 2: Preparation of magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper: The surface modified carbon fiber obtained in step 1 and the softwood fiber with a beating degree of 40 °SR were mixed in water at a ratio of 2:3 to obtain a fiber suspension with a concentration of 0.13 g / mL, which was placed in a pulp disintegrator for 30,000 revolutions, and then wet-formed on a paper sampler to obtain a wet paper web, which was pressed at a pressure of 8 MPa for 3 min. Subsequently, the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper was obtained by drying.

[0035] Compared with unmodified carbon fiber / plant fiber paper, the dielectric loss tangent, magnetic loss tangent and electromagnetic interference shielding performance of the composite material are significantly improved. (Related data see Table 1) pass Figure 1-3 It can be seen from the scanning electron microscope images in that the surfaces of the carbon fibers prepared in all the examples are coated with magnetic nanoparticles / polyaniline to varying degrees. Therefore, it is preliminarily proved that the carbon fibers surface-modified with magnetic nanoparticles / polyaniline have been successfully prepared in this example.

[0036] Note: Dielectric loss tangent and magnetic loss tangent are experimental parameters at 10.01 GHz It can be seen from the data in the table that the modified carbon fiber prepared in the embodiment is added to the plant fiber as a reinforcement, which can enhance the dielectric loss and magnetic loss capacity of the body and improve the electromagnetic interference shielding performance of the composite material. In summary, we have prepared a magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper with good dielectric loss capacity and magnetic loss capacity for electromagnetic interference shielding.

[0037] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0038] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a magnetic nanoparticle / polyaniline surface-modified carbon fiber composite paper, characterized in that: The following steps are involved: Aniline monomer and magnetic nanoparticles are added to the carbon fiber suspension, and then a hydrochloric acid solution is added dropwise and dispersed uniformly, and then kept in an ice water bath to obtain a mixed solution; Ammonium persulfate is first dissolved in precooled deionized water, then added to the above mixed solution for polymerization for 5-15 hours, and then washed to obtain surface-modified carbon fibers of magnetic nanoparticles / polyaniline-modified carbon fibers; The surface-modified carbon fiber and plant fiber are mixed in a mass ratio of 1:9-9:1 in water to obtain a fiber suspension, and after being deflated by a pulp deflagrator, wet-formed on a paper sample copyer to obtain a wet paper web, which is pressed at a pressure of 5 MPa-10 MPa for 1-10 min, and then dried to obtain a magnetic nanoparticle / polyaniline surface-modified carbon fiber composite paper.

2. The method for preparing the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper according to claim 1, characterized in that: The mass ratio of the aniline monomer to the carbon fiber in the carbon fiber suspension is 1:10-1:1, and the mass ratio of the magnetic nanoparticles to the aniline monomer is 1:10-1:

1.

3. The method for preparing the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper according to claim 1, characterized in that: When the hydrochloric acid solution is added dropwise, the hydrochloric acid solution accounts for 0.5%-2.5% of the mixed solution.

4. The method for preparing the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper according to claim 1, characterized in that: The magnetic nanoparticles include one of nano Fe3O4, nano FeNi3 or flaky nano FeNi3 iron-based nanoparticles.

5. The method for preparing the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper according to claim 1, characterized in that: The mass ratio of the ammonium persulfate to aniline is 1:5 to 5:

1.

6. The method for preparing the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper according to claim 1, characterized in that: The deflaking speed in the deflaking machine is 5000-50000 revolutions.

7. The method for preparing the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper according to claim 1, characterized in that: The plant fiber is coniferous wood fiber, broadleaf wood fiber, bamboo pulp fiber or straw pulp fiber.

8. The method for preparing the magnetic nanoparticle / polyaniline surface modified carbon fiber composite paper according to claim 1, characterized in that: The beating degree of the plant fiber is 30°SR~60°SR.

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