Preparation method of a rubber-like composite wave-absorbing material

Abstract

The application relates to the technical field of wave-absorbing materials, and particularly discloses a preparation method of a rubber clay-shaped composite wave-absorbing material, which comprises the following steps: dissolving gelatin in deionized water, uniformly stirring at 50-70 DEG C, cooling to room temperature, and obtaining a gelatin solution; dissolving tannic acid in deionized water, uniformly stirring, and obtaining a tannic acid solution; dissolving polyvinyl alcohol in deionized water, uniformly stirring at 60-70 DEG C, cooling to room temperature, and obtaining a polyvinyl alcohol solution; slowly adding the polyvinyl alcohol solution into the tannic acid solution, ultrasonically treating for 10-20 min, uniformly dispersing, and obtaining a mixed solution; adding the mixed solution into the gelatin solution under stirring, continuously heating and stirring at 50-70 DEG C for 5-10 min, removing supernatant, and obtaining a rubber clay-shaped gelatin / tannic acid / polyvinyl alcohol composite wave-absorbing material. The application has low requirements on production equipment and is easy to be industrialized; and the prepared rubber clay-shaped composite wave-absorbing material has the advantages of strong plasticity, high flexibility and good wave-absorbing performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wave-absorbing material preparation, and particularly relates to a preparation method of a rubber clay-like composite wave-absorbing material. BACKGROUND

[0002] With the wide application of electronic communication technology, especially the popularity of satellite communication, wideband radar, wireless network and multi-band, high-power electronic equipment, the problem of electromagnetic interference is increasingly serious, and designing and manufacturing new high-performance wave-absorbing materials to protect electronic equipment and human beings from electromagnetic interference and radiation pollution has become an important issue of concern in contemporary society. At the same time, the expansion of the electromagnetic emission frequency range and the increasing demand for integrated intelligent and multifunctional electronic devices have further promoted the development of wave-absorbing materials with wideband absorption, lightweight, low cost, high thermal stability and corrosion resistance.

[0003] Traditional wave-absorbing materials such as carbon-based materials (graphene, carbon nanotubes), metal-based materials (transition metal oxides / sulfides, alloys) and conductive polymers have limited controllability and poor processability. Some flexible wave-absorbing materials such as meta-structures and polymer-reinforced composites still have the disadvantages of poor ductility, poor durability and high cost. SUMMARY

[0004] In view of the deficiencies in the prior art, the application provides a simple, efficient and universal preparation method of a new flexible wave-absorbing material.

[0005] Specifically, the application provides a preparation method of a rubber clay-like composite wave-absorbing material, comprising the following steps:

[0006] Dissolve gelatin in deionized water, stir uniformly at 50-70 DEG C, and cool to room temperature to obtain a gelatin solution;

[0007] Dissolve tannic acid in deionized water, stir uniformly, and obtain a tannic acid solution;

[0008] Dissolve polyvinyl alcohol in deionized water, stir uniformly at 60-70 DEG C, and cool to room temperature to obtain a polyvinyl alcohol solution;

[0009] Slowly add the polyvinyl alcohol solution to the tannic acid solution, ultrasonically treat for 10-20 min to make it uniformly dispersed, and obtain a mixed solution;

[0010] Add the mixed solution to the gelatin solution under stirring, continue to heat and stir at 50-70 DEG C for 5-10 min, remove the supernatant, and obtain a rubber clay-like gelatin / tannic acid / polyvinyl alcohol composite wave-absorbing material.

[0011] As a further illustration of the application, the gelatin solution concentration is 0.383 mol / L, the tannin acid solution solution concentration is 0.118 mol / L, and the polyvinyl alcohol solution concentration is 2.270 mol / L.

[0012] As a further illustration of the application, the mass ratio of the gelatin, the tannin acid and the polyvinyl alcohol is 1:1:0.05-0.25.

[0013] As a further illustration of the application, the mass ratio of the gelatin, the tannin acid and the polyvinyl alcohol is 1:1:0.20.

[0014] Compared with the prior art, the application has the following beneficial technical effects:

[0015] The application provides a simple, fast and universal new method for preparing rubber clay-like composite wave-absorbing materials, which has not been reported before. The production raw materials are cheap and easy to obtain, and the method has low requirements for production equipment and is easy to industrialize. The prepared rubber clay-like composite wave-absorbing materials have the advantages of good biocompatibility, strong plasticity, high flexibility and good wave-absorbing performance. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The electromagnetic parameters of the rubber clay-like composite wave-absorbing materials prepared in Example 1 of the application and the calculated wave-absorbing performance are shown in Table 1.

[0017] Figure 2 The electromagnetic parameters of the rubber clay-like composite wave-absorbing materials prepared in Example 2 of the application and the calculated wave-absorbing performance are shown in Table 2.

[0018] Figure 3 The electromagnetic parameters of the rubber clay-like composite wave-absorbing materials prepared in Example 3 of the application and the calculated wave-absorbing performance are shown in Table 3.

[0019] Figure 4 The actual wave-absorbing material X-band and Ku-band samples prepared in the example and the flexibility thereof are shown in Table 4.

[0020] Figure 5 The wave-absorbing performance chart of the rubber clay-like composite wave-absorbing materials prepared in Example 3 after being soaked in tap water for three days is shown in Figure 1.

[0021] Figure 6 The wave-absorbing performance chart of the rubber clay-like composite wave-absorbing materials prepared in Example 3 after being soaked in tap water for five days is shown in Figure 2.

[0022] Figure 7 The wave-absorbing performance chart of the rubber clay-like composite wave-absorbing materials prepared in Example 3 after being soaked in salt water for three days is shown in Figure 3.

[0023] Figure 8The wave-absorbing performance diagram of the putty-like composite wave-absorbing material prepared for Example 3 after being soaked in salt water for five days.

[0024] Figure 9 The electromagnetic parameters of the putty-like composite wave-absorbing material prepared for Comparative Example 1 and the calculated wave-absorbing performance.

[0025] Figure 10 The electromagnetic parameters of the putty-like composite wave-absorbing material prepared for Comparative Example 2 and the calculated wave-absorbing performance. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] Traditional wave-absorbing materials such as carbon-based materials (graphene, carbon nanotubes), metal-based materials (transition metal oxides / sulfides, alloys) and conductive polymers have limited controllability and poor processability. Some flexible wave-absorbing materials such as meta-structures and polymer-reinforced composites still have the disadvantages of poor ductility, poor durability and high cost.

[0028] Therefore, the present application provides a simple, efficient and universal preparation method of a novel flexible wave-absorbing material. Gelatin is a hydrolyzate of natural collagen, which contains amino groups, hydroxyl groups, carboxyl groups and other functional groups, and is easy to modify. Tannic acid molecules contain polyphenol hydroxyl structures, which have ester bonds, carboxyl groups, hydroxyl groups and other functional groups, and can act as a crosslinking agent to form a 3D network with gelatin molecules through multiple hydrogen bonds and hydrophobic interactions. In addition, they all have the advantages of wide sources, good biocompatibility and low price. Therefore, the present application utilizes the characteristics of the above raw materials and combines the technical defects of flexible wave-absorbing materials to apply the above raw materials to the preparation process of wave-absorbing materials. Polyvinyl alcohol contains many hydroxyl groups, which can form hydrogen bonds with amino groups and hydroxyl groups in gelatin and tannic acid molecules, and can be introduced into the reaction system of gelatin and tannic acid to regulate the reaction. After a large number of experiments, it is found that when the ratio of the three is about 1:1:0.20, and the preparation temperature is about 50-70 °C, and after stirring for 5-10 min, the ideal state of the flexible wave-absorbing material in the form of putty can be obtained. The wave-absorbing material has variable shape and strong ductility, and has good flexibility and adhesion. It is found through testing that the flexible wave-absorbing material has excellent wave-absorbing performance, and therefore has good application prospect in the field of wave-absorbing materials.

[0029] The following will be described with reference to specific embodiments:

[0030] Example 1 (mass ratio of gelatin, tannic acid and polyvinyl alcohol 1:1:0.05)

[0031] Take 2.00 g of gelatin and add to 20 mL of deionized water. Stir uniformly at 60 °C to fully dissolve, then cool to room temperature (25 °C) to obtain a gelatin solution. Accurately weigh 2.00 g of tannic acid and add to 10 mL of deionized water. Stir uniformly to fully dissolve to obtain a tannic acid solution. Take 1.00 g of polyvinyl alcohol and add to 10 mL of deionized water. Stir uniformly at 70 °C, then cool to room temperature (25 °C) to obtain a polyvinyl alcohol solution. Slowly drop 1 mL of the polyvinyl alcohol solution into 10 mL of the tannic acid solution, and ultrasonicate for 10 min to disperse uniformly to obtain a mixed solution. Stir the gelatin solution at 70 °C, and add the polyvinyl alcohol and tannic acid mixed solution to the gelatin solution. Stir at 70 °C for 10 min, then discard the supernatant to obtain a gelatin / tannic acid / polyvinyl alcohol composite wave-absorbing material. Figure 1 The electromagnetic parameters of the rubber-like composite wave-absorbing material prepared in this example were tested using a vector network analyzer (VNA, Agilent N5230A, USA), and the calculated wave-absorbing performance is shown. The waveguide method was used to test in the range of 8.2-18 GHz. As the thickness of the sample increased, the effective bandwidth of RL<-10 dB was 5.63 GHz when the thickness was 1.50 mm. Figure 4 The actual material X-band and Ku-band samples and their flexibility are shown.

[0032] Example 2 (mass ratio of gelatin, tannic acid and polyvinyl alcohol 1:1:0.2)

[0033] Take 2.00 g of gelatin and add to 20 mL of deionized water. Stir uniformly at 60 °C to fully dissolve, then cool to room temperature (25 °C) to obtain a gelatin solution. Accurately weigh 2.00 g of tannic acid and add to 10 mL of deionized water. Stir uniformly to fully dissolve to obtain a tannic acid solution. Take 1.00 g of polyvinyl alcohol and add to 10 mL of deionized water. Stir uniformly at 70 °C, then cool to room temperature (25 °C) to obtain a polyvinyl alcohol solution. Slowly drop 4 mL of the polyvinyl alcohol solution into 10 mL of the tannic acid solution, and ultrasonicate for 10 min to disperse uniformly to obtain a mixed solution. Stir the gelatin solution at 70 °C, and add the polyvinyl alcohol and tannic acid mixed solution to the gelatin solution. Stir at 70 °C for 10 min, then discard the supernatant to obtain a gelatin / tannic acid / polyvinyl alcohol composite wave-absorbing material. Figure 2The electromagnetic parameters and the calculated wave absorption performance of the rubber-like composite wave absorbing material prepared in the embodiment were tested by using a vector network analyzer (VNA, Agilent N5230A, USA). The waveguide method was used to test in the range of 8.2-18 GHz. With the increase of the thickness of the test sample, the effective bandwidth of RL <-10 dB was 6.05 GHz when the thickness was 1.55 mm. Figure 4 The X-band and Ku-band samples of the actual material and the flexibility thereof were exhibited.

[0034] Example 3 (mass ratio of gelatin, tannic acid and polyvinyl alcohol 1:1:0.25)

[0035] 2.00 g of gelatin was weighed and added to 20 mL of deionized water, stirred uniformly at 60 °C, and fully dissolved, and then cooled to room temperature (25 °C) to obtain a gelatin solution; 2.00 g of tannic acid was accurately weighed and added to 10 mL of deionized water, stirred uniformly, and fully dissolved to obtain a tannic acid solution; 1.00 g of polyvinyl alcohol was taken and added to 10 mL of deionized water, stirred uniformly at 70 °C, and then cooled to room temperature (25 °C) to obtain a polyvinyl alcohol solution. 5 mL of the polyvinyl alcohol solution was slowly added to 10 mL of the tannic acid solution, and ultrasonic treatment was performed for 10 min to make it uniformly dispersed to obtain a mixed solution. The gelatin solution was stirred at a certain temperature, and the polyvinyl alcohol and tannic acid mixed solution was added to the gelatin solution, heated and stirred at 70 °C for 10 min, and then the supernatant was discarded to obtain a gelatin / tannic acid / polyvinyl alcohol composite wave absorbing material. Figure 3 The electromagnetic parameters and the calculated wave absorption performance of the rubber-like composite wave absorbing material prepared in the embodiment were tested by using a vector network analyzer (VNA, Agilent N5230A, USA). The waveguide method was used to test in the range of 8.2-18 GHz. With the increase of the thickness of the test sample, the effective bandwidth of RL <-10 dB was 6.05 GHz when the thickness was 1.55 mm. Figure 4 The X-band and Ku-band samples of the actual material and the flexibility thereof were exhibited.

[0036] Resistance test

[0037] Water resistance

[0038] The sample in Example 3 to which 5 mL of polyvinyl alcohol solution was added was selected, and the wave absorption performance of the sample after being soaked in tap water for a certain period of time was recorded. Figure 5 , Figure 6 The wave absorption performance diagrams after being soaked for three days and five days, respectively, are shown in FIGS. 6 and 7. It can be seen from the figures that the bandwidth after being soaked in water for a certain period of time changes by less than 1.15 compared with the original sample, and the sample still has good wave absorption performance.

[0039] Salt tolerance

[0040] The sample of Example 3 with 5 mL of polyvinyl alcohol solution was selected and immersed in self-made salt water (5 g of salt, 100 mL of warm boiled water), and the wave absorption performance after soaking in the salt water for a certain time was recorded. The wave absorption performance after soaking for three days and five days is shown in Figures 3 and 4, respectively. It can be seen from the figures that the bandwidth after soaking in the salt water for a certain time changes less than 1.00 compared with the original sample, and the sample still has good wave absorption performance. Figure 7 、 Figure 8 The wave absorption performance after soaking for three days and five days is shown in Figures 3 and 4, respectively. It can be seen from the figures that the bandwidth after soaking in the salt water for a certain time changes less than 1.00 compared with the original sample, and the sample still has good wave absorption performance.

[0041] Comparative Example 1 (mass ratio of gelatin, tannic acid and polyvinyl alcohol 1:1:0.25)

[0042] 2.00 g of gelatin was weighed and added to 20 mL of deionized water, stirred uniformly at 60 °C, and fully dissolved, and then cooled to room temperature (25 °C) to obtain a gelatin solution; 2.00 g of tannic acid was accurately weighed and added to 10 mL of deionized water, stirred uniformly, and fully dissolved to obtain a tannic acid solution; 1.00 g of polyvinyl alcohol was taken and added to 10 mL of deionized water, stirred uniformly at 70 °C, and then cooled to room temperature (25 °C) to obtain a polyvinyl alcohol solution. 5 mL of the polyvinyl alcohol solution was slowly dropped into 10 mL of the tannic acid solution, and ultrasonic treatment was performed for 10 min to make it uniformly dispersed to obtain a mixed solution. The gelatin solution was stirred at a certain temperature, and the polyvinyl alcohol and tannic acid mixed solution was added to the gelatin solution, and heated and stirred at 90 °C for 20 min, and then the supernatant was discarded to obtain a gelatin / tannic acid / polyvinyl alcohol composite wave absorption material. Figure 9 The electromagnetic parameters of the composite wave absorption material prepared in the comparative example were tested by using a vector network analyzer (VNA, Agilent N5230A, USA), and the calculated wave absorption performance is shown in Figure 5. The waveguide method was used to test in the range of 8.2-18 GHz, and with the increase of the thickness of the test sample, the effective bandwidth of RL<-10 dB was 2.06 GHz when the thickness was 1.77 mm. It can be seen that: when the stirring time and temperature are increased, the electromagnetic wave absorption performance decreases obviously.

[0043] Comparative Example 2 (mass ratio of gelatin, tannic acid and polyvinyl alcohol 1:0.6:0.25)

[0044] Take 2.00 g of gelatin, add to 20 mL of deionized water, stir evenly at 60 °C, make it fully dissolved, then cool to room temperature (25 °C), get the gelatin solution; accurately take 2.00 g of tannic acid, add to 10 mL of deionized water, stir evenly, make it fully dissolved, get the tannic acid solution; take another 1.00 g of polyvinyl alcohol, add to 10 mL of deionized water, stir evenly at 70 °C, then cool to room temperature (25 °C), get the polyvinyl alcohol solution. Take 5 mL of polyvinyl alcohol solution and slowly drop into 6 mL of tannic acid solution, ultrasonic for 10 min, make it evenly dispersed, get the mixed solution. Stir the gelatin solution at a certain temperature, and add the polyvinyl alcohol and tannic acid mixed solution to the gelatin solution, heat and stir at 50 °C for 10 min, then pour away the supernatant, get the gelatin / tannic acid / polyvinyl alcohol composite wave-absorbing material. The following Figure 10 The electromagnetic parameters of the composite wave-absorbing material prepared in the above-mentioned comparative example were tested by using a vector network analyzer (VNA, Agilent N5230A, USA), and the calculated wave-absorbing performance was shown in the following table. The test was carried out by using waveguide method in the range of 8.2-18 GHz. With the increase of the thickness of the test sample, the effective bandwidth of RL <-10 dB was 3.07 GHz when the thickness was 2.03 mm. It can be seen from comparative example 3 that the electromagnetic wave absorbing performance decreased obviously after changing the ratio of gelatin and tannic acid.

[0045] It should be noted that in this paper, terms such as "including", "containing" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or equipment.

[0046] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a rubbery composite wave-absorbing material, characterized by, The application relates to a gelatin / tannic acid / polyvinyl alcohol composite wave-absorbing material. Gelatin is dissolved in deionized water, stirred uniformly at 50-70 DEG C, and cooled to room temperature to obtain a gelatin solution with a concentration of 0.383 mol / L; Tannic acid is dissolved in deionized water, stirred uniformly to obtain a tannic acid solution with a concentration of 0.118 mol / L; Polyvinyl alcohol is dissolved in deionized water, stirred uniformly at 60-70 DEG C, and cooled to room temperature to obtain a polyvinyl alcohol solution with a concentration of 2.270 mol / L; The polyvinyl alcohol solution is slowly added into the tannic acid solution, ultrasonically treated for 10-20 min, and uniformly dispersed to obtain a mixed solution; The mixed solution is added into the gelatin solution under stirring, continuously heated and stirred at 50-70 DEG C for 5-10 min, and then the supernatant is removed to obtain the rubber-like gelatin / tannic acid / polyvinyl alcohol composite wave-absorbing material; wherein the mass ratio of the gelatin, the tannic acid and the polyvinyl alcohol is 1:1:0.05-0.

25.

2. The method for preparing the clay-like composite microwave absorbing material as described in claim 1, characterized in that, The mass ratio of the gelatin, the tannic acid and the polyvinyl alcohol is 1:1:0.20.

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