Modified glass fiber cloth and preparation method of flexible wave-absorbing material

Abstract

The application discloses a preparation method of modified glass fiber cloth, and in-situ generates a ferriferous oxide shell layer on the surface of the glass fiber cloth, namely, the modification of the glass fiber cloth is completed. The application simultaneously solves the key technical problems that the electromagnetic loss mechanism is single and the wave-absorbing performance is insufficient due to the random distribution of wave-absorbing agents, and the tensile strength of the material is low due to the flexible resin base.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flexible wave-absorbing materials, and particularly relates to a modified glass fiber cloth and a preparation method of a flexible wave-absorbing material. BACKGROUND

[0002] The rapid development of electromagnetic technology not only promotes the upgrading of military equipment, significantly improves people's living standards, but also brings a large amount of electromagnetic pollution, electromagnetic radiation, electromagnetic information leakage and other negative effects. The best way to eliminate the above negative effects is to use wave-absorbing materials to convert electromagnetic energy into heat energy in the interaction with electromagnetic waves. Among the many types of wave-absorbing materials, flexible wave-absorbing materials have received widespread attention due to their good shape adaptability, structural toughness and light weight. However, current flexible wave-absorbing materials generally dissipate electromagnetic energy through polarization loss, electrical conduction loss and magnetic loss, which are intrinsic electromagnetic loss mechanisms of the materials, and in order to balance the light weight characteristics, the loading amount of the wave-absorbing agent of the flexible wave-absorbing material is limited, so it is difficult to meet the design goals of "thin, light, wide and strong" performance at the same time. SUMMARY

[0003] The purpose of the present application is to provide a modified glass fiber cloth and a preparation method of a flexible wave-absorbing material. The present application simultaneously solves the key technical problems of the single electromagnetic loss mechanism and insufficient wave-absorbing performance of the flexible wave-absorbing material due to the random distribution of the wave-absorbing agent, and the low tensile strength of the material due to the flexible resin substrate.

[0004] Technical solution. A preparation method of a modified glass fiber cloth, in which a ferric oxide shell layer is generated in situ on the surface of the glass fiber cloth, thereby completing the modification of the glass fiber cloth.

[0005] In the aforementioned preparation method of the modified glass fiber cloth, the surface of the glass fiber cloth is subjected to plasma surface treatment for 5-15 min before modification.

[0006] In the aforementioned preparation method of the modified glass fiber cloth, the surface of the glass fiber cloth is washed with an alcohol solution and then dried at 80°C for 4-6 h before plasma surface treatment.

[0007] In the aforementioned preparation method of the modified glass fiber cloth, the modification is performed by a hydrothermal method, and the specific method is as follows: the glass fiber cloth substrate is added to a mixed solution prepared by mixing PEG, FeSO4·7H2O, H2O2 and ammonia water, and after the reaction is completed, a large number of ferric oxide nanoparticles are firmly grown on the surface of the glass fiber cloth, and then the glass fiber cloth modified by ferric oxide is obtained after cleaning and drying.

[0008] In the aforementioned preparation method of the modified glass fiber cloth, the configuration method of the mixed solution is as follows:

[0009] (a) adding PEG and FeSO4·7H2O in deionized water successively, stirring uniformly;

[0010] (b) adding ammonia and H2O2 successively while keeping stirring, mixing uniformly to obtain.

[0011] In the aforementioned preparation method of the modified glass fiber cloth, during the modification, the glass fiber cloth is put into the mixed solution for sufficient infiltration, and is put into a reaction kettle for sealing, and is taken out after being reacted at 160℃ for 4-10h, and is repeatedly washed with deionized water, and is dried at 80℃ for 6h to obtain the iron tetroxide modified glass fiber cloth.

[0012] In the aforementioned preparation method of the modified glass fiber cloth, during the modification, the adding amount of PEG and FeSO4·7H2O in step (a) is 5-20g / L and 12-22g / L respectively; and the adding amount of ammonia and H2O2 in step (b) is 175-225mL / L and 5-15mL / L.

[0013] In the aforementioned preparation method of the modified glass fiber cloth, the infiltration time is 20-30min.

[0014] A preparation method of a flexible wave-absorbing material made of the modified glass fiber cloth prepared by the aforementioned preparation method, wherein the modified glass fiber cloth is used as a filter cloth, and a carbonyl iron suspension is used as a filter object, and the filter cloth is alternately operated by vacuum filtration and drying until the surface density of the filter cloth after drying meets 0.062-0.068g / cm 2 , so as to obtain the flexible wave-absorbing material.

[0015] The aforementioned preparation method of the carbonyl iron suspension is as follows: 5wt.%-20wt.% carbonyl iron and 10wt.%-30wt.% ethyl cellulose are added into anhydrous ethanol and mixed uniformly to obtain.

[0016] Beneficial effects: the flexible wave-absorbing material prepared by the application uses glass fiber cloth as a flexible substrate, and a two-dimensional conductive network is formed on the surface of the iron tetroxide after the surface modification of the iron tetroxide, so as to improve the electric conduction loss capacity; meanwhile, the intrinsic magnetic loss is introduced on the surface of the substrate through the filter method, and on the other hand, the orientation distribution of the carbonyl iron is realized by using the micron-level height difference between the warp fibers and the weft fibers on the surface of the substrate, so as to increase the effective interaction area of the carbonyl iron and the electromagnetic wave, and multiple eddy current centers are generated in the carbonyl iron in the plane, so as to induce a new structural loss mechanism. The linkage of multiple intrinsic loss mechanisms and structural loss mechanisms is realized in the application, so as to realize the wide-frequency absorption in a thin thickness.

[0017] The flexible wave-absorbing material prepared by the two-step method of hydrothermal reaction and vacuum filtration with glass fiber cloth as a flexible substrate successfully integrates intrinsic electromagnetic loss mechanisms such as electric conduction loss and magnetic loss, and at the same time, a new structural loss mechanism is induced by the oriented distribution of carbonyl iron on the surface of the glass fiber cloth, which effectively improves the electromagnetic wave attenuation ability of the material. The flexible wave-absorbing material prepared in the application has an effective absorption bandwidth of 5.82 GHz at a thickness of only 2.0 mm, which has obvious advantages compared with typical wave-absorbing materials, and the comparison results are shown in Table 1. In addition, the flexible wave-absorbing material prepared in the application also has good mechanical properties, and the tensile strength is as high as 37.1 Mpa. The application can better meet the miniaturization development requirements of various complex-shaped equipment, and realize good electromagnetic protection effect in limited and complex space through the flexible wave-absorbing material.

[0018] The preparation method of the application has the advantages of simple process, low cost, no need for complex synthesis equipment, and can realize large-scale mass production, and has good application value and economic benefits in the field of aviation manufacturing technology.

[0019] Table 1

[0020] BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The preparation flow chart of the flexible wave-absorbing material of the application;

[0022] Figure 2 The super-depth three-dimensional graph of the flexible wave-absorbing material of the application;

[0023] Figure 3 The X-ray diffraction graph of the iron tetroxide modified glass fiber cloth prepared in Example 1;

[0024] Figure 4 The scanning electron microscope graph of the flexible wave-absorbing material prepared in Example 1;

[0025] Figure 5 The electromagnetic simulation graph of the flexible wave-absorbing material prepared in Example 1;

[0026] Figure 6 The reflection loss graph of the flexible wave-absorbing material prepared in Example 1;

[0027] Figure 7 The tensile strength graph of the flexible wave-absorbing material prepared in Example 1. DETAILED DESCRIPTION

[0028] Example 1. In this embodiment, the preparation flow chart of the flexible wave-absorbing material is shown in Figure 1 , which comprises the following steps:

[0029] Step 1 ultrasonic cleaning of glass fiber cloth in alcohol solution, remove oil stains and other impurities, dry the glass fiber cloth at 80 DEG C for 4h, then carry out 5min plasma surface treatment on the glass fiber cloth.

[0030] Step 2 preparation of hydrothermal reaction solution: first add PEG and FeSO4·7H2O in deionized water, stir the above solution uniformly, then add ammonia and H2O2 into the mixed solution, and transfer the above solution into a reaction kettle containing a polytetrafluoroethylene lining after mixing uniformly.

[0031] In step 2, the addition amount of deionized water, PEG and FeSO4·7H2O is 50mL, 0.5g and 0.8g respectively, and the addition amount of ammonia and H2O2 is 10mL and 0.27mL respectively, and the stirring time is 10min.

[0032] Step 3: Put the plasma treated glass fiber cloth into the above solution and soak it thoroughly, seal the reaction kettle, take it out after reacting at 160 DEG C for 6h, rinse it repeatedly with deionized water, and dry it at 80 DEG C for 6h to obtain the glass fiber cloth modified by ferroferric oxide.

[0033] In step 3, the soaking time of the glass fiber cloth in the mixed solution is 20min.

[0034] Step 4: Preparation of carbonyl iron suspension: the proportion of carbonyl iron suspension is 5wt.% carbonyl iron and 10wt.% ethyl cellulose, and the dispersing agent is anhydrous ethanol, and the carbonyl iron suspension can be obtained by adding carbonyl iron and ethyl cellulose into anhydrous ethanol and mechanically stirring for 3h.

[0035] Step 5: using the ferroferric oxide modified glass fiber cloth as the filter cloth and the uniformly dispersed carbonyl iron suspension as the filter object, the oriented deposition of carbonyl iron on the surface of the glass fiber cloth is realized by vacuum filtration, and the filtration and drying operations are alternately carried out for multiple times until the surface density of the filter cloth after drying meets 0.065g / cm 2 , see Figure 2 .

[0036] As can be seen from Figure 1 , the whole preparation process of the application does not need complex and large equipment, the preparation method is simple, the materials used are all conventional materials, and the cost is low, which is beneficial to realize large-scale production of flexible wave-absorbing materials.

[0037] From Figure 2 , it can be seen that the glass fiber cloth surface is arranged with channels with a depth of several microns to several microns, which provides a structural basis for the oriented distribution of the flaky carbonyl iron.

[0038] From Figure 3 , it can be seen that the ferroferric oxide is generated on the surface of the glass fiber cloth after the hydrothermal reaction.

[0039] from Figure 4 It can be observed that most of the carbonyl iron is distributed vertically or obliquely in the channels between the glass fibers, and the orientation distribution is achieved by the channel structure on the surface of the glass fiber cloth.

[0040] from Figure 5 The current vector distribution results show that when carbonyl iron is horizontally distributed on the surface of glass fiber cloth, only one eddy current center is generated in its plane. However, when carbonyl iron is tilted or vertically distributed on the surface of glass fiber cloth, the number of eddy current centers in its plane increases. Therefore, it can be proved that carbonyl iron can induce a new structural loss mechanism by tilting or vertically distributing grooves several micrometers to tens of micrometers deep on the surface of glass fiber cloth, thereby further enhancing the electromagnetic loss capability of the material.

[0041] Depend on Figure 6 It can be seen that when the thickness of the flexible absorbing material is 2.0 mm, it exhibits an effective absorption bandwidth of 5.82 GHz, which is significantly superior to traditional absorbing materials.

[0042] Depend on Figure 7 It is known that the maximum tensile strength of flexible microwave absorbing materials can reach 37.1 MPa, which has certain mechanical performance advantages compared with traditional flexible microwave absorbing materials.

[0043] Example 2

[0044] In this embodiment, the preparation process of the flexible microwave absorbing material includes the following steps:

[0045] Step 1: Ultrasonically clean the fiberglass cloth in an alcohol solution to remove oil and other impurities. After drying the fiberglass cloth at 80°C for 4 hours, perform plasma surface treatment on the fiberglass cloth for 5 minutes.

[0046] Step 2: Prepare the hydrothermal reaction solution: Add PEG and FeSO4·7H2O to deionized water in sequence and stir the solution until homogeneous; while stirring, add ammonia and H2O2 to the mixed solution in sequence and mix until homogeneous. Then transfer the solution to a reaction vessel with a polytetrafluoroethylene liner.

[0047] In step 2, the amounts of deionized water, PEG, and FeSO4·7H2O added are 50 mL, 0.5 g, and 0.8 g, respectively, while the amounts of ammonia and H2O2 added are 10 mL and 0.27 mL, respectively, and the stirring time is 10 min.

[0048] Step 3: The plasma-treated glass fiber cloth is fully immersed in the above solution, the reaction vessel is sealed, and after reacting at 160°C for 6 hours, it is taken out, rinsed repeatedly with deionized water, and dried at 80°C for 6 hours to obtain the iron oxide-modified glass fiber cloth.

[0049] wherein in step 3, the glass fiber cloth is immersed in the mixed solution for 20 min.

[0050] Step 4: Preparation of the carbonyl iron suspension: the carbonyl iron suspension is prepared by mixing 10 wt.% of carbonyl iron, 10 wt.% of ethyl cellulose, and anhydrous ethanol as a dispersant, and stirring the mixture for 3 h to obtain the carbonyl iron suspension.

[0051] Step 5: The glass fiber cloth modified by the ferriferrous oxide is used as a filter cloth, and the uniformly dispersed carbonyl iron suspension is used as a filter object. The oriented deposition of the carbonyl iron on the surface of the glass fiber cloth is achieved by vacuum filtration. The filtration and drying operations are alternately performed for multiple times until the surface density of the filter cloth after drying meets the requirement of 0.068 g / cm 2 .

[0052] Example 3

[0053] A flexible wave-absorbing material, which is composed of a glass fiber cloth modified by ferriferrous oxide and a surface-loaded carbonyl iron.

[0054] The glass fiber cloth needs to be washed with an alcohol solution before in-situ growth of the ferriferrous oxide. After drying at 80℃ for 4-6 h, the glass fiber cloth is subjected to plasma surface treatment for 5-15 min.

[0055] The ferriferrous oxide shell layer generated in-situ on the surface of the glass fiber cloth is obtained by a hydrothermal method. Specifically, the glass fiber cloth substrate subjected to the plasma surface treatment is added to a solution prepared by mixing polyvinyl alcohol (PEG), ferrous sulfate heptahydrate (FeSO4·7H2O), hydrogen peroxide (H2O2), and ammonia water. After the reaction, a large amount of ferriferrous oxide nanoparticles are firmly grown on the surface of the glass fiber cloth. After washing and drying, the glass fiber cloth modified by the ferriferrous oxide is obtained.

[0056] The preparation method of the aforementioned glass fiber cloth modified by the ferriferrous oxide specifically includes the following steps:

[0057] (a) PEG and FeSO4·7H2O are sequentially added to deionized water, and the solution is stirred uniformly;

[0058] (b) While maintaining the stirring, ammonia water and H2O2 are sequentially added to the mixed solution, and after uniform mixing, the solution is transferred to a reaction kettle containing a polytetrafluoroethylene liner;

[0059] (c) The glass fiber cloth subjected to the plasma treatment is immersed in the solution for sufficient time, the reaction kettle is sealed, and after reaction at 160℃ for 4-10 h, the glass fiber cloth is taken out, washed repeatedly with deionized water, and dried at 80℃ for 6 h to obtain the glass fiber cloth modified by the ferriferrous oxide.

[0060] The adding amount of deionized water, PEG and FeSO4·7H2O in step (a) is 50 mL, 0.5 g and 0.8 g respectively.

[0061] The adding amount of ammonia water and H2O2 in step (b) is 10 mL and 0.27 mL respectively, and the stirring time is 5-10 min.

[0062] The soaking time of the glass fiber cloth in the mixed solution in step (c) is 20-30 min.

[0063] The preparation method of the flexible wave-absorbing material is as follows: the above-obtained Fe3O4 modified glass fiber cloth is used as a filter cloth, and a uniformly dispersed carbonyl iron suspension is used as a filtering object, and the orientation distribution of the carbonyl iron on the surface of the Fe3O4 modified glass fiber cloth is realized by vacuum filtration.

[0064] The proportion of the carbonyl iron suspension is 5wt.%-10wt.% of carbonyl iron and 10wt.%-20wt.% of ethyl cellulose, and the dispersing agent is anhydrous ethanol, and the carbonyl iron suspension can be obtained by adding the carbonyl iron and the ethyl cellulose into the anhydrous ethanol and mechanically stirring for 3-5 h.

[0065] The Fe3O4 modified glass fiber cloth is repeatedly subjected to the filtration and drying alternately until the surface density of the filter cloth after drying meets 0.062-0.068 g / cm 2 The flexible wave-absorbing material is obtained.

Claims

1. A method for preparing a flexible microwave absorbing material, characterized in that, Modified glass fiber cloth was used as the filter cloth, and carbonyl iron suspension was used as the filter object. Vacuum filtration and drying were performed alternately until the areal density of the dried filter cloth met the requirements of 0.062–0.068 g / cm³. 2 The modification method of the modified glass fiber cloth is as follows: a ferric oxide shell layer is generated in situ on the surface of the glass fiber cloth, thus completing the modification of the glass fiber cloth. The modification is carried out by hydrothermal method: the glass fiber cloth substrate is added to a mixed solution prepared by PEG, FeSO4·7H2O, H2O2 and ammonia. After the reaction is completed, a large number of ferric oxide nanoparticles are firmly grown on the surface of the glass fiber cloth. After cleaning and drying, the glass fiber cloth modified by ferric oxide is obtained.

2. The preparation method according to claim 1, characterized in that, Before modification, the surface of the glass fiber cloth is subjected to plasma surface treatment for 5 to 15 minutes.

3. The preparation method according to claim 2, characterized in that, Before plasma surface treatment, the surface of the glass fiber cloth is washed with an alcohol solution and then dried at 80°C for 4–6 hours.

4. The preparation method according to claim 1, characterized in that, The method for preparing the mixed solution is as follows: (a) Add PEG and FeSO4·7H2O to deionized water one after another and stir until homogeneous; (b) While stirring, add ammonia and H2O2 in sequence and mix well to obtain the final product.

5. The preparation method according to claim 4, characterized in that, During modification, the glass fiber cloth is fully immersed in the mixed solution and then placed in a sealed reaction vessel. After reacting at 160°C for 4–10 hours, it is removed, repeatedly rinsed with deionized water, and dried at 80°C for 6 hours to obtain the iron oxide-modified glass fiber cloth.

6. The preparation method according to claim 4, characterized in that, During modification, the addition amounts of PEG and FeSO4·7H2O in step (a) are 5–20 g / L and 12–22 g / L, respectively; the addition amounts of ammonia and H2O2 in step (b) are 175–225 mL / L and 5–15 mL / L, respectively.

7. The preparation method according to claim 5, characterized in that, The soaking time is 20 to 30 minutes.

8. The preparation method according to claim 1, characterized in that, The carbonyl iron suspension is prepared as follows: 5 wt.% to 20 wt.% carbonyl iron and 10 wt.% to 30 wt.% ethyl cellulose are added to anhydrous ethanol and mixed well.

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