FeCo / C / PAN composite wave-absorbing fiber and preparation method and application thereof

Abstract

The invention relates to a FeCo / C / PAN composite wave-absorbing fiber as well as a preparation method and application thereof. FeCo / C and PAN are mixed to prepare a continuous wave-absorbing fiber through a wet spinning technology. The prepared wave-absorbing fiber has excellent wave-absorbing performance, the minimum reflection loss can reach-43.83 dB, and the effective absorption bandwidth is 1.39 GHz. Meanwhile, the wave-absorbing fiber has better impedance matching and attenuation constant and can be applied to the field of electromagnetic wave absorbing materials.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic wave absorption, and particularly relates to an FeCo / C / PAN composite absorbing fiber and a preparation method and application thereof. Background Art

[0002] In recent years, with the rapid development of information technology, wider electromagnetic wave frequency bands such as 5G have been gradually developed and widely applied in advanced communication fields and cutting-edge military reconnaissance equipment. At the same time, a series of electromagnetic pollution and security vulnerabilities have been brought. Electromagnetic radiation can endanger human health and the natural environment, interfere with the normal operation of electronic devices, and also cause electronic information leakage. Electromagnetic wave absorption technology has great applications in life safety, national defense technology, and information health. Therefore, the research and development of electromagnetic wave absorption materials are urgently needed by the country.

[0003] At present, existing absorbing fibers mainly focus on nanofibers and fiber modification, and there is still a lack of precise preparation technology for polymer fiber absorbing materials, especially a method for directly preparing absorbing fibers by combining absorbing particles with polymers. Therefore, proposing a new strategy for constructing absorbing hybrid polymer fibers and developing new methods for impedance matching and magnetoelectric loss regulation are of great significance for the preparation of absorbing fibers. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an FeCo / C / PAN composite absorbing fiber and a preparation method and application thereof.

[0005] The present invention provides an FeCo / C / PAN composite fiber, which is obtained by spinning with raw materials containing FeCo / C and PAN.

[0006] Further, the mass of FeCo / C in the FeCo / C / PAN composite fiber accounts for 10% - 30% of the total mass of the composite fiber.

[0007] The present invention provides a preparation method of an FeCo / C / PAN composite fiber, including:

[0008] Mixing FeCo / C, polyacrylonitrile PAN, and a solvent, stirring to obtain a spinning solution, wet spinning after degassing, washing, and drying to obtain the FeCo / C / PAN composite fiber.

[0009] Preferably, the preparation of FeCo / C includes: carbonizing Fe-Co PBA cages to obtain FeCo / C.

[0010] The Fe-Co PBA cages: preparing hollow Fe-Co PBA cages by a coprecipitation method.

[0011] The preparation of Fe-Co PBA cages includes: dissolving potassium ferricyanide in water to form solution A; dissolving cobalt acetate tetrahydrate, trisodium citrate dihydrate and polyvinylpyrrolidone in water to form solution B; adding solution B to solution A under stirring conditions, stirring, and then putting the mixed solution into an oven for reaction, and finally obtaining hollow Fe-Co PBA cages through washing and drying.

[0012] In the preparation of Fe-Co PBA cages, the concentration of potassium ferricyanide in solution A is 2 - 4 mg / mL; the mass ratio of cobalt acetate tetrahydrate, trisodium citrate dihydrate to polyvinylpyrrolidone (PVP, Mw = 37000 - 44000 Da) in solution B is 1:1:8 - 12, and the concentration of solids in solution B is 5 - 10 mg / mL; the reaction temperature is 75 - 85 °C, and the time is 10 - 24 h; the washing is carried out by washing with deionized water and ethanol in sequence; the drying process conditions are drying overnight at 60 - 70 °C.

[0013] Preferably, the carbonization process parameters are: the heating rate during carbonization is 3 - 7 °C / min, the carbonization temperature is 850 - 950 °C, and the carbonization time is 1 - 3 h.

[0014] Preferably, the solvent is a mixed solution of dimethyl sulfoxide DMSO and water; the mass ratio of PAN, DMSO to water in the spinning solution is (10 - 20):(80 - 86):1.

[0015] Preferably, the stirring is carried out at 60 - 65 °C for 1 - 4 h, and the stirring speed is 80 - 95 r / min.

[0016] Preferably, the process of wet spinning includes: the coagulation bath for wet spinning is composed of DMSO and water, where the mass ratio of DMSO to water is 5 - 8:3. During the wet spinning process, the extrusion speed of the spinning dope is 18 mL / h, the rotation speed of the first-stage stretching is 15 - 20 r / min, the rotation speed of the second-stage stretching is 20 - 30 r / min, and the winding speed is 20 - 30 r / min.

[0017] The defoaming is ultrasonic defoaming.

[0018] The washing is water washing, the drying temperature is room temperature, and the drying time is 1 - 2 days.

[0019] Preferably, the mass of FeCo / C in the FeCo / C / PAN composite fiber accounts for 10% - 30% of the total mass of the composite fiber.

[0020] The present invention provides an application of the FeCo / C / PAN composite fiber or the FeCo / C / PAN composite fiber prepared by any of the above methods in the field of electromagnetic wave absorption.

[0021] Beneficial effects

[0022] The FeCo / C / PAN absorbing fiber prepared by the method of wet spinning in the present invention provides an effective reference for the preparation of FeCo / C-based fiber-type absorbing materials.

[0023] The FeCo / C / PAN composite fiber obtained in the present invention has good electromagnetic properties. When the content of FeCo / C is 30%, the maximum reflection loss can reach -43.83 dB, and the effective absorption bandwidth is as high as 1.39 GHz at this time, showing excellent absorbing properties.

[0024] The FeCo / C / PAN composite fiber obtained in the present invention has good impedance matching properties. By combining the magnetic carbon-based absorbing material with PAN, an absorbing fiber with electromagnetic synergistic effect is constructed. Description of the Drawings

[0025] Figure 1 are the XRD patterns of (a) FeCo / C absorbing particles and (b) FeCo / C / PAN composite absorbing fibers;

[0026] Figure 2 are the SEM and EDS patterns of FeCo / C / PAN composite absorbing fibers;

[0027] Figure 3 (a - f) are the electromagnetic parameter diagrams of FeCo / C / PAN composite absorbing fibers in the range of 2 - 18 GHz;

[0028] Figure 4 (a - c) are the three-dimensional reflection loss diagrams of FeCo / C / PAN composite absorbing fibers in the range of 2 - 18 GHz;

[0029] Figure 5 (a - b) are the comparison diagrams of impedance matching and reflection loss and the attenuation constant diagrams of FeCo / C / PAN composite absorbing fibers in the range of 2 - 18 GHz;

[0030] Figure 6 is the comparison diagram of the best reflection loss of FeCo / C / PAN absorbing fibers. Detailed Embodiments

[0031] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0032] Example 1

[0033] Preparation of Fe-Co PBA cages: Weigh 0.2 g of potassium ferricyanide and dissolve it in 60 mL of deionized water to form solution A. Weigh 0.3 g of cobalt acetate tetrahydrate, 0.3 g of trisodium citrate dihydrate, and 3 g of polyvinylpyrrolidone (PVP, K30, Mw = 40,000 Da) respectively and dissolve them in 40 mL of deionized water to form solution B. Under magnetic stirring, slowly add solution B to solution A within 1 min. After continuous stirring for about 1 min, transfer the mixed solution to an oven and react at 80 °C for 24 h. Wash the purple-black precipitate three times with deionized water and ethanol, and dry it overnight at 70 °C to obtain Fe-Co PBA cages.

[0034] Preparation of FeCo / C: Heat the Fe-Co PBA cages obtained in the above steps in a tubular furnace at a heating rate of 5 °C / min to 900 °C and carbonize for 2 h to obtain FeCo / C.

[0035] Preparation of 10% absorber-loaded absorbing fibers: FeCo / C accounts for 10% of the total mass of the fibers. The mass ratio of PAN, DMSO, and water in the spinning solution is 15:84:1. That is, weigh 0.33 g of FeCo / C and 3 g of PAN respectively, mix them evenly, add a mixed solvent composed of 16.8 g of DMSO and 0.2 g of water, and mechanically stir at 60 °C for 3 h to form a uniform spinning dope, and then ultrasonic defoaming for 30 min.

[0036] Draw the ultrasonic defoamed spinning dope with a 20 mL syringe, load it into a wet spinning device, set the injection speed to 18 mL / h, the preset primary stretching speed to 15 r / min, the secondary stretching speed to 20 r / min, and the winding speed to 25 r / min. The coagulation bath for wet spinning is composed of DMSO and water, and the mass ratio of DMSO to water is 7:3. The spinning dope is first extruded from a 21G spinneret needle into the coagulation bath for shaping, the fiber is pulled by forceps to the stretching device, and then to the winding device. According to the actual situation, adjust the spinning parameters of the fiber. Under the conditions of an injection speed of 18 mL / h, a primary stretching speed of 20 r / min, a secondary stretching speed of 30 r / min, and a winding speed of 30 r / min, obtain the FeCo / C / PAN-10 as-spun fibers.

[0037] Wash the prepared FeCo / C / PAN-10 as-spun fibers repeatedly in water and dry them at room temperature for two days to obtain FeCo / C / PAN-10 fibers.

[0038] As Figure 1 Figure a is the XRD pattern of the absorber FeCo / C obtained in this example, indicating the successful preparation of FeCo / C.

[0039] Example 2

[0040] In this example, microwave-absorbing fibers loaded with 20% microwave absorbers were prepared: FeCo / C accounted for 20% of the total mass of the fibers, and the mass ratio of PAN, DMSO, and water in the spinning solution was 15:84:1. That is, 0.75 g of FeCo / C (the same as in Example 1) and 3 g of PAN were weighed and uniformly mixed, and a mixed solvent composed of 16.8 g of DMSO and 0.2 g of water was added thereto. The mixture was mechanically stirred at 60 °C for 3 h to form a uniform spinning solution, and then defoamed by ultrasonic treatment for 30 min.

[0041] The spinning solution after ultrasonic defoaming was drawn with a 20 mL syringe and loaded into a wet spinning device. The injection speed was set at 18 mL / h, the preset primary stretching speed was 15 r / min, the secondary stretching speed was 20 r / min, and the winding speed was 25 r / min. The coagulation bath for wet spinning was composed of DMSO and water, and the mass ratio of DMSO to water was 7:3. The spinning solution was first extruded from a 21G spinneret needle into the coagulation bath for shaping, and the fiber was pulled by forceps to the stretching device and then to the winding device. According to the actual situation, the spinning parameters of the fiber were adjusted, and FeCo / C / PAN-20 nascent fibers were obtained at an injection speed of 18 mL / h, a primary stretching speed of 20 r / min, a secondary stretching speed of 30 r / min, and a winding speed of 30 r / min.

[0042] The prepared FeCo / C / PAN-20 nascent fibers were washed repeatedly in water and dried at room temperature for two days to obtain FeCo / C / PAN-20 fibers.

[0043] Example 3

[0044] In this example, microwave-absorbing fibers loaded with 30% microwave absorbers were prepared: FeCo / C accounted for 30% of the total mass of the fibers, and the mass ratio of PAN, DMSO, and water in the spinning solution was 15:84:1. That is, 1.29 g of FeCo / C (the same as in Example 1) and 3 g of PAN were weighed and uniformly mixed, and a mixed solvent composed of 16.8 g of DMSO and 0.2 g of water was added thereto. The mixture was mechanically stirred at 60 °C for 3 h to form a uniform spinning solution, and then defoamed by ultrasonic treatment for 30 min.

[0045] With a 20 mL syringe, draw the degassed spinning solution by ultrasonic treatment, load it into the wet spinning device, set the injection speed at 18 mL / h, the preset primary stretching speed at 15 r / min, the secondary stretching speed at 20 r / min, and the winding speed at 25 r / min. The coagulation bath for wet spinning consists of DMSO and water, with the mass ratio of DMSO to water being 7:3. The spinning solution is first extruded from a 21G spinneret needle into the coagulation bath for shaping, and the fiber is then drawn by tweezers to the stretching device and further to the winding device. According to the actual situation, adjust the spinning parameters of the fiber. Under the conditions of an injection speed of 18 mL / h, a primary stretching speed of 20 r / min, a secondary stretching speed of 30 r / min, and a winding speed of 30 r / min, the FeCo / C / PAN-10 as-spun fiber is obtained.

[0046] Wash the prepared FeCo / C / PAN-30 as-spun fiber several times in water and dry it at room temperature for two days to obtain the FeCo / C / PAN-30 fiber.

[0047] As Figure 1 Figure b shows the XRD of the FeCo / C / PAN composite absorbing fiber. The peaks of PAN and FeCo / C can be seen, and as the content of FeCo / C increases, the metal peaks increase. The XRD pattern indicates the successful preparation of the FeCo / C / PAN fiber.

[0048] As Figure 2 Figures show the SEM and EDS images of the FeCo / C / PAN composite absorbing fiber. It can be seen from the figures that the diameter of the FeCo / C / PAN composite absorbing fiber is 95 - 146 μm, and it can be seen from the EDS pattern that there are four elements, C, N, Fe, and Co, in the fiber.

[0049] Use a vector network analyzer to measure the electromagnetic parameters of the FeCo / C / PAN fiber in the frequency range of 2 - 18 GHz (the fibers obtained under different FeCo / C contents are denoted as FeCo / C / PAN-x (x = 10, 20, and 30)), and calculate the tangent of the dielectric constant (tanδ ε ) and the tangent of the permeability (tanδ μ ). As Figure 3 shown, Figure 3 in (a), (b), and (c), it can be seen that the real part (ε′) and the imaginary part (ε") of the complex dielectric constant of FeCo / C / PAN-x, and tanδ ε all increase with the increase in the content of FeCo / C, indicating that the dielectric loss ability of FeCo / C / PAN-x increases with the increase in the content of FeCo / C. Figure 3 in (d), (e), and (f), it can be seen that the real part (μ′) and the imaginary part (μ") of the complex permeability of FeCo / C / PAN-x, and tanδ μThe change is not obvious with the increase of the content of FeCo / C, indicating that the magnetic loss ability of FeCo / C / PAN-x is basically the same.

[0050] As Figure 4 Figure 5 shows the three-dimensional reflection loss (3D RL) diagram of FeCo / C / PAN fibers in the range of 2 - 18 GHz. It can be seen that the minimum reflection loss (RL min ) of FeCo / C / PAN-10 is -9.38 dB. Due to the low content of FeCo / C and low dielectric loss, there is no absorption bandwidth. The RL min of FeCo / C / PAN-20 at 4.5 mm is -11.57 dB, and the effective absorption bandwidth is 0.78 GHz; the RL min of FeCo / C / PAN-30 at 2.5 mm is -43.83 dB, and the effective absorption bandwidth is 1.39 GHz. This shows that when the content of FeCo / C is 30%, it has the best wave absorption performance.

[0051] As Figure 5 (a) shows the comparison of Z and RL of FeCo / C / PAN fibers within the frequency range of 2 - 18 GHz under the best absorption performance. It can be seen that only the impedance matching of FeCo / C / PAN-30 is close to 1. Therefore, the impedance matching of FeCo / C / PAN-30 is the best. As Figure 5 (b) shows the attenuation constant of FeCo / C / PAN fibers within 2 - 18 GHz. It can be seen that with the increase of the content of FeCo / C, the attenuation constant gradually increases, indicating that when the content of FeCo / C is 30%, FeCo / C / PAN-30 has the best attenuation performance for electromagnetic waves. The previous analysis shows that the impedance matching of FeCo / C / PAN-30 is the best, which proves that FeCo / C / PAN-30 has the best wave absorption performance.

[0052] Comparative Example 1

[0053] In this example, wave-absorbing fibers loaded with 40% wave-absorbing particles were prepared: FeCo / C accounted for 40% of the total mass of the fibers, and the mass ratio of PAN, DMSO, and water in the spinning solution was 15:84:1. That is, 2 g of FeCo / C (the same as in Example 1) and 3 g of PAN were weighed and uniformly mixed, and a solvent composed of 16.8 g of DMSO and 0.2 g of water was added thereto, and mechanically stirred at 60 °C for 3 h to form a uniform spinning solution, and then ultrasonic defoaming was carried out for 30 min.

[0054] With a 20 mL syringe, draw the degassed spinning solution by ultrasound, load it into the wet spinning apparatus, and set the injection speed at 18 mL / h, the first-stage stretching speed at 10 r / min, the second-stage stretching speed at 15 r / min, and the winding speed at 15 r / min. The coagulation bath for wet spinning consists of DMSO and water, with the mass ratio of DMSO to water being 7:3. The spinning solution is first extruded from a 21G spinneret needle and enters the coagulation bath for shaping. Compared with the above absorbent content, when the FeCo / C content increases to 40%, the fibers are prone to breakage and uneven thickness, making it difficult to spin uniform long filaments and collect them.

Claims

1. A FeCo / C / PAN composite fiber, characterized in that, The composite fiber is obtained by spinning with raw materials containing FeCo / C and PAN.

2. A preparation method of FeCo / C / PAN composite fiber, comprising: Mixing FeCo / C, polyacrylonitrile PAN, and a solvent, stirring to obtain a spinning solution, subjecting it to wet spinning after degassing, washing, and drying to obtain FeCo / C / PAN composite fiber.

3. The preparation method according to claim 2, characterized in that, The preparation of FeCo / C includes: carbonizing Fe-Co PBA cages to obtain FeCo / C.

4. The preparation method according to claim 3, wherein The carbonization process parameters: the heating rate during carbonization is 3 - 7 °C / min, the carbonization temperature is 850 - 950 °C, and the carbonization time is 1 - 3 h.

5. The preparation method according to claim 2, wherein The solvent is a mixed solution of dimethyl sulfoxide DMSO and water; the mass ratio of PAN, DMSO, and water in the spinning solution is (10 - 20):(80 - 86):

1.

6. The preparation method according to claim 2, characterized in that, The stirring is carried out at 60 - 65 °C for 1 - 4 h.

7. The preparation method according to claim 2, wherein The process of the wet spinning includes: the coagulation bath for wet spinning is composed of DMSO and water, where the mass ratio of DMSO to water is 5 - 8:

3. During the wet spinning process, the extrusion speed of the spinning dope is 18 mL / h, the rotation speed of the first-stage stretching is 15 - 20 r / min, the rotation speed of the second-stage stretching is 20 - 30 r / min, and the winding speed is 20 - 30 r / min.

8. The preparation method according to claim 2, characterized in that, The mass of FeCo / C in the FeCo / C / PAN composite fiber accounts for 10% - 30% of the total mass of the composite fiber.

9. Application of the FeCo / C / PAN composite fiber according to claim 1 or the FeCo / C / PAN composite fiber prepared by any of the methods according to claims 2 - 8 in the field of electromagnetic wave absorption.

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