Polyaniline-doped broadband wave-absorbing composite material and preparation method thereof

Abstract

The present invention discloses a polyaniline-doped broadband absorbing composite material and its preparation method. CoNi alloy nanoparticles are prepared using a hydrothermal method. Then, a polyaniline-coated CoNi composite is formed on the surface of the CoNi alloy using an in-situ polymerization method. Finally, the polyaniline / CoNi composite is combined with carbon fibers and polypropylene to produce the polyaniline-doped broadband absorbing composite material. The resulting absorbing material exhibits excellent electrical conductivity, a minimum reflection loss of less than 38 dB, and an absorption band less than 10 dB greater than 4.5 GHz, demonstrating excellent broadband absorbing performance. The resulting absorbing material also exhibits excellent mechanical properties, with the tensile strength of the strips exceeding 25 MPa, demonstrating superior overall performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of absorbing materials, and relates to a wide-band radar absorbing energetic cloud damage material, a preparation method thereof, and applications thereof. Background Art

[0002] As electronic products increasingly adopt low-power, high-speed, and highly integrated circuits, these devices are more vulnerable to electromagnetic interference than ever before. This has led to the emergence of absorbing materials. Absorbing materials are generally composed of a base material and an absorbing medium, and they have excellent absorption and loss properties for electromagnetic waves projected onto the material surface.

[0003] Magnetic metal micropowder CoNi is an important electromagnetic wave absorber. It exhibits a high imaginary magnetic permeability and magnetic loss tangent, primarily absorbing and attenuating electromagnetic waves through mechanisms such as hysteresis loss, eddy current loss, and natural resonance loss. However, its susceptibility to oxidation, poor corrosion resistance, and high density severely restrict its widespread application in the field of absorbing materials. Conductive polymers offer advantages such as low density, ease of processing, and low cost. Their conjugated electron system allows the material's conductivity to vary within the range of insulators, semiconductors, and metals, making them an ideal alternative to traditional metal absorbers in electromagnetic shielding.

[0004] There has been no public report on using a polyaniline-coated CoNi composite material with good wave-absorbing properties obtained by in-situ polymerization as a filler to prepare a carbon fiber reinforced polypropylene-based composite wave-absorbing material. Summary of the Invention

[0005] The present invention relates to a wide-band absorbing composite material doped with polyaniline, as well as its preparation method and application. A polyaniline-coated CoNi composite with excellent absorbing properties is obtained by in-situ polymerization. The composite material is then introduced into polypropylene with carbon fiber to prepare a composite material. The resultant composite material combines excellent mechanical properties with absorbing properties, and has good application prospects in the fields of electromagnetic protection and military stealth materials.

[0006] The present invention is achieved through the following technical solutions.

[0007] The present invention provides a wide-band wave-absorbing composite material doped with polyaniline and a preparation method thereof, which includes the following processes: preparation of CoNi nanoparticles, preparation of a polyaniline-coated CoNi composite material, and preparation of a carbon fiber reinforced polypropylene-based wide-band wave-absorbing material.

[0008] A wide-band wave-absorbing composite material doped with polyaniline and a preparation method thereof specifically include the following steps:

[0009] Step 1: CoCl2·6H2O and NiCl2·6H2O are uniformly mixed in 50-100 mL of polyethylene glycol at a molar ratio of 1:1, and then hydrazine hydrate with a mass concentration of 5% to 10% is added and stirred to obtain a mixed solution;

[0010] Step 2: placing the mixed solution obtained in step 1 in a high-pressure reactor, reacting at 150-190° C. for 10-16 hours, washing with ethanol and deionized water 3-5 times, and drying at 60-80° C. to obtain CoNi nanoparticles;

[0011] Step 3: 20 mL of aniline monomer and 5-10 g of CoNi nanoparticles obtained in step 2 are dispersed in 50-100 mL of 1 mol / L protonic acid to prepare a mixed solution, and then 20-50 g of ammonium persulfate is added to the mixed solution. The mixture is reacted under magnetic stirring in an ice bath at 0°C for 4-6 hours, and the obtained product is filtered, washed, and dried to obtain a polyaniline-coated CoNi composite.

[0012] Step 4: 5-10 g of carbon fiber is placed in an acetone solution and soaked at 60-70 ° C for 10-15 hours, then repeatedly washed with deionized water and dried at 60-80 ° C to obtain debonded carbon fiber, and the debonded carbon fiber is placed in a 10-20 mol / L nitric acid solution and oxidized at 85-95 ° C for 1-2 hours, then repeatedly washed with deionized water and dried at 60-80 ° C to obtain pre-oxidized carbon fiber;

[0013] Step 5: Take 10-15g of the polyaniline / CoNi composite obtained in step 3, 5-8g of the pre-oxidized carbon fiber obtained in step 4, 2-3g of maleic anhydride and 20-25g of polypropylene, place them in a torque rheometer and mix them at 180-210°C for 10-15min, and then hot press them at 190-200°C to obtain a wide-band absorbing composite material doped with polyaniline.

[0014] Preferably, the protonic acid is hydrochloric acid, sulfuric acid, dodecylbenzenesulfonic acid and camphorsulfonic acid.

[0015] The energetic composite obtained by the present invention detonates within the target's range to form a broadband electromagnetic wave absorption cloud with a long hovering time. By absorbing and attenuating the target's electromagnetic wave signals, the cloud paralyzes enemy command and communication, leading to a loss of combat effectiveness. The electromagnetic wave absorption cloud has a reflection loss of less than -50dB, an absorption band less than -10dB greater than 4GHz, and a hovering time of more than 40 seconds per 100g dose. This demonstrates excellent broadband electromagnetic cloud damage effectiveness and has promising application prospects for non-lethal damage to mobile targets.

[0016] Beneficial effects of the present invention:

[0017] (1) The present invention adopts a hydrothermal method to prepare CoNi nanoparticles, and then adopts an in-situ polymerization method to obtain a polyaniline-coated CoNi composite. The obtained polyaniline / CoNi composite material exhibits excellent wave absorption performance, with a minimum reflection loss of less than -38dB and an absorption band width less than -10dB greater than 4.5GHz. The excellent magnetic properties of CoNi nanoparticles promote the magnetic loss of electromagnetic waves, and the good electrical conductivity of polyaniline is beneficial to the dielectric loss of electromagnetic waves. The difference in electrical conductivity between polyaniline and CoNi particles allows the two to form an interface effect, which promotes the absorption and loss of electromagnetic waves. In addition, the polyaniline-coated CoNi structure improves the defects of CoNi particles such as easy oxidation, poor corrosion resistance, and high density.

[0018] (2) The absorbing material obtained by the present invention has excellent mechanical properties, and the tensile strength of the spline is greater than 25MPa, making it an absorbing material with excellent comprehensive performance. The present invention uses carbon fiber reinforced polypropylene to prepare a polyaniline-doped polypropylene-based composite material. The addition of carbon fiber not only enhances the mechanical properties of the composite material, but also improves the conductivity of the polypropylene matrix, thereby further improving the absorbing performance of the composite material. Because the carbon fiber surface is smooth and has poor compatibility with polypropylene, the present invention performs surface treatment on the carbon fiber and uses maleic anhydride as a "bridge" to connect the carbon fiber and the polypropylene matrix, significantly improving the compatibility between the two. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an SEM image of the brittle fracture surface of the polyaniline-doped broadband microwave-absorbing composite material prepared in Example 1. DETAILED DESCRIPTION

[0020] In order to have a clearer understanding of the technical features of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0021] Example 1

[0022] (1) CoCl2.6H2O and NiCl2.6H2O were uniformly mixed in 50 mL of polyethylene glycol at a molar ratio of 1:1, and then hydrazine hydrate with a mass concentration of 5% was added and stirred to obtain a mixed solution;

[0023] (2) placing the mixed solution obtained in step (1) in a high-pressure reactor, reacting at 160° C. for 12 h, washing with ethanol and deionized water five times, and drying at 80° C. to obtain CoNi nanoparticles;

[0024] (3) 20 mL of aniline monomer and 5 g of CoNi nanoparticles obtained in step (2) were dispersed in 50 mL of 1 mol / L hydrochloric acid to prepare a mixed solution, and then 20 g of ammonium persulfate was added to the mixed solution. After magnetic stirring in an ice bath at 0°C for 5 h, the obtained product was filtered, washed, and dried to obtain a polyaniline-coated CoNi composite.

[0025] (4) 5 g of carbon fiber was placed in an acetone solution and soaked at 70 ° C for 12 h, then repeatedly washed with deionized water and dried at 80 ° C to obtain debonded carbon fiber, and the debonded carbon fiber was placed in a 15 mol / L nitric acid solution and oxidized at 85 ° C for 2 h, then repeatedly washed with deionized water and dried at 80 ° C to obtain pre-oxidized carbon fiber;

[0026] (5) 10 g of polyaniline / CoNi composite, 5 g of pre-oxidized carbon fiber, 2 g of maleic anhydride and 20 g of polypropylene were placed in a torque rheometer and mixed at 200 °C for 15 min. Then, hot-pressed at 200 °C was obtained to obtain a wide-band absorbing composite material based on polyaniline doping.

[0027] like Figure 1 This is the SEM image of the brittle fracture surface of the prepared polyaniline-doped wide-band absorbing composite material. The SEM image shows an uneven scaly surface, indicating that the composite material has a ductile fracture and good flexibility, and the polyaniline / CoNi conductive filler and carbon fiber are well dispersed in the polypropylene group.

[0028] Example 2

[0029] (1) CoCl2.6H2O and NiCl2.6H2O were uniformly mixed in 50 mL of polyethylene glycol at a molar ratio of 1:1, and then hydrazine hydrate with a mass concentration of 5% was added and stirred to obtain a mixed solution;

[0030] (2) placing the mixed solution obtained in step (1) in a high-pressure reactor, reacting at 160° C. for 12 h, washing with ethanol and deionized water five times, and drying at 80° C. to obtain CoNi nanoparticles;

[0031] (3) 20 mL of aniline monomer and 5 g of CoNi nanoparticles obtained in step (2) were dispersed in 50 mL of 1 mol / L sulfuric acid to prepare a mixed solution, and then 20 g of ammonium persulfate was added to the mixed solution. After magnetic stirring in an ice bath at 0°C for 5 h, the obtained product was filtered, washed, and dried to obtain a polyaniline-coated CoNi composite.

[0032] (4) 5 g of carbon fiber was placed in an acetone solution and soaked at 70 ° C for 12 h, then repeatedly washed with deionized water and dried at 80 ° C to obtain debonded carbon fiber, and the debonded carbon fiber was placed in a 15 mol / L nitric acid solution and oxidized at 85 ° C for 2 h, then repeatedly washed with deionized water and dried at 80 ° C to obtain pre-oxidized carbon fiber;

[0033] (5) 10 g of polyaniline / CoNi composite, 5 g of pre-oxidized carbon fiber, 2 g of maleic anhydride and 20 g of polypropylene were placed in a torque rheometer and mixed at 200 °C for 15 min. Then, hot-pressed at 200 °C was obtained to obtain a wide-band absorbing composite material based on polyaniline doping.

[0034] Example 3

[0035] (1) CoCl2.6H2O and NiCl2.6H2O were uniformly mixed in 50 mL of polyethylene glycol at a molar ratio of 1:1, and then hydrazine hydrate with a mass concentration of 5% was added and stirred to obtain a mixed solution;

[0036] (2) placing the mixed solution obtained in step (1) in a high-pressure reactor, reacting at 160° C. for 12 h, washing with ethanol and deionized water five times, and drying at 80° C. to obtain CoNi nanoparticles;

[0037] (3) 20 mL of aniline monomer and 5 g of CoNi nanoparticles obtained in step (2) were dispersed in 50 mL of 1 mol / L dodecylbenzenesulfonic acid to prepare a mixed solution, and then 20 g of ammonium persulfate was added to the mixed solution. After magnetic stirring in an ice bath at 0°C for 5 h, the obtained product was filtered, washed, and dried to obtain a polyaniline-coated CoNi composite.

[0038] (4) 5 g of carbon fiber was placed in an acetone solution and soaked at 70 ° C for 12 h, then repeatedly washed with deionized water and dried at 80 ° C to obtain debonded carbon fiber, and the debonded carbon fiber was placed in a 15 mol / L nitric acid solution and oxidized at 85 ° C for 2 h, then repeatedly washed with deionized water and dried at 80 ° C to obtain pre-oxidized carbon fiber;

[0039] (5) 10 g of polyaniline / CoNi composite, 5 g of pre-oxidized carbon fiber, 2 g of maleic anhydride and 20 g of polypropylene were placed in a torque rheometer and mixed at 200 °C for 15 min. Then, hot-pressed at 200 °C was obtained to obtain a wide-band absorbing composite material based on polyaniline doping.

[0040] Example 4

[0041] (1) CoCl2.6H2O and NiCl2.6H2O were uniformly mixed in 50 mL of polyethylene glycol at a molar ratio of 1:1, and then hydrazine hydrate with a mass concentration of 5% was added and stirred to obtain a mixed solution;

[0042] (2) placing the mixed solution obtained in step (1) in a high-pressure reactor, reacting at 160° C. for 12 h, washing with ethanol and deionized water five times, and drying at 80° C. to obtain CoNi nanoparticles;

[0043] (3) 20 mL of aniline monomer and 5 g of CoNi nanoparticles obtained in step (2) were dispersed in 50 mL of 1 mol / L camphorsulfonic acid to prepare a mixed solution, and then 20 g of ammonium persulfate was added to the mixed solution. After magnetic stirring in an ice bath at 0°C for 5 h, the obtained product was filtered, washed, and dried to obtain a polyaniline-coated CoNi composite;

[0044] (4) 5 g of carbon fiber was placed in an acetone solution and soaked at 70 ° C for 12 h, then repeatedly washed with deionized water and dried at 80 ° C to obtain debonded carbon fiber, and the debonded carbon fiber was placed in a 15 mol / L nitric acid solution and oxidized at 85 ° C for 2 h, then repeatedly washed with deionized water and dried at 80 ° C to obtain pre-oxidized carbon fiber;

[0045] (5) 10 g of polyaniline / CoNi composite, 5 g of pre-oxidized carbon fiber, 2 g of maleic anhydride and 20 g of polypropylene were placed in a torque rheometer and mixed at 200 °C for 15 min. Then, hot-pressed at 200 °C was obtained to obtain a wide-band absorbing composite material based on polyaniline doping.

[0046] Table 1 shows the absorbing properties and mechanical properties of the broadband absorbing composite materials doped with polyaniline prepared in Examples 1 to 4. The minimum reflection loss values ​​(R Lmin ) is between -39dB and -37dB, and the reflection loss is less than -10dB (99%). a ) is between 4.4GHz and 4.8GHz, showing good electromagnetic wave absorption and loss effects; the tensile strength of the obtained absorbing material is greater than 25MPa, and it has good mechanical properties.

[0047] Table 1. Absorption and mechanical properties of the composite materials obtained in the examples

[0048] Group Example 1 Example 2 Example 3 Example 4 <![CDATA[R Lmin (dB)]]> -38 -37 -38 -39 <![CDATA[E a (GHz)]]> 4.5 4.4 4.6 4.8 Tensile strength (MPa) 25 27 25 26

Claims

1. A method for preparing a wide-band microwave-absorbing composite material doped with polyaniline, characterized in that: The steps include: Step 1: CoCl2·6H2O and NiCl2·6H2O are uniformly mixed in 50-100 mL of polyethylene glycol at a molar ratio of 1:1, and then hydrazine hydrate with a mass concentration of 5% to 10% is added and stirred to obtain a mixed solution; Step 2: placing the mixed solution obtained in step 1 in a high-pressure reactor, reacting at 150-190° C. for 10-16 hours, washing with ethanol and deionized water 3-5 times, and drying at 60-80° C. to obtain CoNi nanoparticles; Step 3: 20 mL of aniline monomer and 5-10 g of CoNi nanoparticles obtained in step 2 are dispersed in 50-100 mL of 1 mol / L protonic acid to prepare a mixed solution, and then 20-50 g of ammonium persulfate is added to the mixed solution. The mixture is reacted under magnetic stirring in an ice bath at 0°C for 4-6 hours, and the obtained product is filtered, washed, and dried to obtain a polyaniline-coated CoNi composite. Step 4: 5-10 g of carbon fiber is placed in an acetone solution and soaked at 60-70 ° C for 10-15 hours, then repeatedly washed with deionized water and dried at 60-80 ° C to obtain debonded carbon fiber, and the debonded carbon fiber is placed in a 10-20 mol / L nitric acid solution and oxidized at 85-95 ° C for 1-2 hours, then repeatedly washed with deionized water and dried at 60-80 ° C to obtain pre-oxidized carbon fiber; Step 5: Take 10-15g of the polyaniline / CoNi composite obtained in step 3, 5-8g of the pre-oxidized carbon fiber obtained in step 4, 2-3g of maleic anhydride and 20-25g of polypropylene, place them in a torque rheometer and mix them at 180-210°C for 10-15min, and then hot press them at 190-200°C to obtain a wide-band absorbing composite material doped with polyaniline.

2. The method for preparing a wide-band microwave-absorbing composite material doped with polyaniline according to claim 1, characterized in that: The protonic acid in step 3 is hydrochloric acid, sulfuric acid, dodecylbenzenesulfonic acid and camphorsulfonic acid.

Images