A polystyrene foam-based flame-retardant wave-absorbing material and a preparation method thereof
By introducing magnetic sepiolite fibers and modified graphene oxide into polystyrene foam to prepare composite aerogels, the problems of flammability of polystyrene foam and insufficient performance of traditional electromagnetic wave absorbing materials are solved, achieving high-efficiency wave absorption and flame retardant properties, and improving the safety and stability of the material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LINGKUN TECH (TIANJIN) CO LTD
- Filing Date
- 2025-09-22
- Publication Date
- 2026-06-23
AI Technical Summary
Polystyrene foam is flammable, and traditional electromagnetic wave absorbing materials have problems such as high density, easy corrosion, low absorption intensity, and narrow effective absorption bandwidth, making them difficult to apply in complex environments.
Composite aerogels were prepared using magnetic sepiolite fibers and modified graphene oxide. Magnetic metals were loaded via thermal decomposition, and combined with one-dimensional magnetic sepiolite fibers and two-dimensional modified graphene oxide to form a three-dimensional oriented porous structure. The impedance matching was adjusted and magnetic nanoparticles were introduced to enhance the microwave absorption performance. Furthermore, a dense carbon layer was formed at high temperature by modifying graphene oxide with ionic liquid, which constituted a physical barrier to block the transfer of heat and oxygen.
It significantly improves the microwave absorption performance, expands the effective absorption bandwidth, enhances the material's skeletal stability and flame retardant properties, and improves application safety.
Abstract
Description
Technical Field
[0001] This invention relates to the field of microwave absorbing materials technology, specifically to a flame-retardant microwave absorbing material based on polystyrene foam and its preparation method. Background Technology
[0002] Polystyrene foam is widely used in building insulation, product packaging, chemical production, automotive, and aerospace industries due to its lightweight, good thermal insulation, excellent water resistance, high compressive strength, superior shock absorption, and good weather resistance. However, polystyrene foam is flammable and releases large amounts of toxic fumes and gases when burning, posing a serious threat to life and property. Therefore, improving its flame-retardant properties is crucial. Meanwhile, in today's rapidly developing electronic technology landscape, electromagnetic pollution has become the fourth largest form of pollution after air, water, and noise pollution. Electromagnetic absorbing materials can convert electromagnetic energy into other forms of energy, such as heat or mechanical energy, effectively addressing electromagnetic radiation issues.
[0003] Traditional electromagnetic wave absorbing materials, such as magnetic metals, ferrites, conductive polymers, and ceramics, often suffer from problems such as high density, susceptibility to corrosion, low absorption intensity, and narrow effective absorption bandwidth, severely limiting their practical application in complex environments. In contrast, carbon-based materials have attracted much attention due to their unique advantages: on the one hand, carbon-based materials have characteristics such as low density, good corrosion resistance, stable chemical properties, abundant resources, and low cost; on the other hand, the rich microstructures of carbon-based materials, including one-dimensional carbon nanotubes and carbon nanofibers, two-dimensional graphene, and three-dimensional porous carbon and carbon aerogels, provide a broad structural design space for controlling electromagnetic wave absorption performance. However, pure carbon aerogels are relatively brittle and easily damaged under external forces, and carbon aerogels have high dielectric properties, which can easily lead to impedance mismatch problems, making it difficult to obtain good wave absorption performance.
[0004] Therefore, we propose a flame-retardant microwave absorbing material based on polystyrene foam and its preparation method. Summary of the Invention
[0005] The purpose of this invention is to provide a flame-retardant microwave absorbing material based on polystyrene foam and its preparation method, so as to solve the problems raised in the prior art.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] A method for preparing a flame-retardant microwave absorbing material based on polystyrene foam includes the following steps:
[0008] Step S1: Magnetic sepiolite fibers are dispersed in sodium dodecylbenzenesulfonate solution and ultrasonically treated for 1-2 hours to obtain a magnetic sepiolite fiber dispersion; the magnetic sepiolite fiber dispersion and modified graphene oxide dispersion are mixed evenly, ascorbic acid is added, stirred evenly, and reduced at 75-85℃ for 30-60 minutes to obtain a composite hydrogel; the composite hydrogel is frozen, thawed, washed, and dried to obtain a composite aerogel;
[0009] Step S2: Combine composite aerogel, flame retardant, film-forming agent, dispersant, defoamer and deionized water to obtain microwave absorbing coating;
[0010] Step S3: Add expanded polystyrene beads into the microwave absorbing coating, stir evenly, dry, and mold to obtain a flame-retardant microwave absorbing material based on polystyrene foam.
[0011] Furthermore, the liquid-to-solid ratio of the sodium dodecylbenzenesulfonate solution to the magnetic sepiolite fiber is (100-200) mL:1 g, and the mass fraction of the sodium dodecylbenzenesulfonate solution is 0.05-0.5%.
[0012] Furthermore, the volume ratio of the magnetic sepiolite fiber dispersion to the modified graphene oxide dispersion is 1:(1-3); the concentration of the modified graphene oxide dispersion is 5-10 mg / mL, and the solvent is deionized water.
[0013] Furthermore, the preparation method of the magnetic sepiolite fiber is as follows:
[0014] Carbonyl iron, tetracarbonyl nickel, and xylene were mixed evenly to obtain a magnetic metal solution. Dried sepiolite fibers were added, nitrogen gas was introduced, and a pyrolysis reaction was carried out. The solution was cooled to room temperature, discharged, washed with anhydrous ethanol, filtered, and dried to obtain magnetic sepiolite fibers.
[0015] Furthermore, the concentration of the magnetic metal solution is 40-60 wt%, and the mass ratio of carbonyl iron to tetracarbonyl nickel is 3:(1-2).
[0016] Furthermore, the liquid-to-solid ratio of the magnetic metal solution to the dried sepiolite fiber is (5-10) mL: 1 g.
[0017] Furthermore, the pyrolysis reaction temperature is controlled by a three-stage programmed heating method: the first stage is from room temperature to 100-150℃, with a heating rate of 0.4-0.8℃ / min; the second stage is from 100-150℃ to 120-200℃, with a heating rate of 0.03-0.20℃ / min; and the third stage is from 120-200℃ to 135-220℃, with a heating rate of 0.05-0.40℃ / min.
[0018] Furthermore, the modified graphene oxide is prepared as follows:
[0019] Graphene oxide was dispersed in a mixed solution of anhydrous ethanol and deionized water, and 3-chloropropyltriethoxysilane was added. The mixture was stirred at 60-70℃ for 6-12 h. After filtration, washing, and drying, silanized graphene oxide was obtained. Acetonitrile and N-octylpyridine bis(trifluoromethanesulfonyl)imide salt were mixed evenly to obtain an ionic liquid solution. The silanized graphene oxide was dispersed in the ionic liquid solution and refluxed magnetically at 80-85℃ for 12-24 h to obtain modified graphene oxide.
[0020] Furthermore, the mass ratio of the graphene oxide, anhydrous ethanol, deionized water and 3-chloropropyltriethoxysilane is 1:(15-20):(3-5):(1-3).
[0021] Furthermore, the liquid-to-solid ratio of the acetonitrile to N-octylpyridine bis(trifluoromethanesulfonyl)imide salt is (40-50) mL: 1 g.
[0022] Furthermore, the solid-liquid ratio of the silanized graphene oxide to the ionic liquid solution is 10 g: (40-50) mL.
[0023] Furthermore, the mass ratio of the modified graphene oxide to ascorbic acid is 1:(1-5).
[0024] Further, the microwave absorbing coating comprises the following components by weight: 10-20 parts of composite aerogel, 15-30 parts of flame retardant, 20-35 parts of film-forming agent, 0.3-0.5 parts of dispersant, 0.2-0.4 parts of defoamer, 0.1-0.3 parts of thickener, and 30-40 parts of deionized water.
[0025] Furthermore, the film-forming agent is a styrene-acrylic emulsion with a solid mass fraction of 45-55%.
[0026] Furthermore, the flame retardant is one or more of expanded graphite, ammonium polyphosphate, pentaerythritol, or aluminum hydroxide.
[0027] Furthermore, the mass ratio of the expanded polystyrene beads to the microwave absorbing coating is 100:(65-85).
[0028] Furthermore, during the molding process, steam is introduced into the molding machine for heating, with a steam pressure of 0.1-0.3 MPa and a heating time of 30-60 minutes.
[0029] Compared with the prior art, the beneficial effects of the present invention are:
[0030] Based on the adsorption of magnetic metals (Fe, Ni) by sepiolite fibers, this invention loads the magnetic metals in situ onto the surface and channels of sepiolite fibers through thermal decomposition, which can achieve a uniform and dispersed distribution of the magnetic metals. This distribution helps to improve the magnetic response and wave absorption performance of the material. The modified graphene oxide is prepared by bonding ionic liquids to the interlayer and surface of silanized graphene oxide.
[0031] A composite aerogel with a three-dimensional oriented porous structure was prepared by freeze-drying using one-dimensional magnetic sepiolite fibers and two-dimensional modified graphene oxide as raw materials. The magnetic sepiolite fibers doped into the composite aerogel not only reduce the dielectric constant and adjust impedance matching, but also increase magnetic loss by introducing magnetic nanoparticles, thus significantly reducing the minimum reflection loss and expanding the effective absorption bandwidth, thereby significantly improving its microwave absorption performance. Furthermore, sepiolite fibers themselves are a high-temperature resistant silicate mineral, and their introduction greatly enhances the skeletal stability of the composite material. The loaded magnetic particles may catalyze the carbonization of sepiolite and the polymer matrix, while the ionic liquid-modified graphene oxide can form a dense and robust carbon layer at high temperatures. The synergistic effect of these two components constitutes a physical barrier, effectively blocking the transfer of heat and oxygen, interrupting the combustion cycle, and thus endowing the material with excellent flame retardant properties, significantly improving its application safety. Detailed Implementation
[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0033] It should be noted that there are no special restrictions on the suppliers of all raw materials involved in this invention. Exemplary examples include (in this embodiment) sepiolite fiber: item number 005, from Lingshou County Tusheng Mineral Products Co., Ltd.; graphene oxide: model DN-20DY, from Zhejiang Zhitai Nano-Micro New Materials Co., Ltd.; film-forming agent: 45-55wt% styrene-acrylic emulsion; dispersant: BK-735; defoamer: BYK-028; thickener: hydroxyethyl cellulose; flame retardant: a 1:1 mass ratio of expanded graphite and ammonium polyphosphate; N-octylpyridine bis(trifluoromethanesulfonyl)imide salt: item number S65058, from Shanghai Yuanye Biotechnology Co., Ltd.
[0034] The preparation method of the expanded polystyrene beads used in this embodiment is as follows: the expandable polystyrene beads are placed in water vapor and pre-foamed for 55 seconds in water vapor with a vapor pressure of 0.5 MPa and a temperature of 100°C. After the pre-foaming is completed, the beads are cured at room temperature for 20 hours to obtain expanded polystyrene beads. The expandable polystyrene beads are from Shenghao Plastic Raw Materials Co., Ltd., grade 301H, with a particle size of 0.3-0.5 mm.
[0035] In the following examples and comparative examples, 1 part equals 1g.
[0036] Example 1: A method for preparing a flame-retardant microwave absorbing material based on polystyrene foam, comprising the following processes:
[0037] Step S1: Disperse 10 parts of magnetic sepiolite fiber into 1000 mL of 0.05 wt% sodium dodecylbenzenesulfonate solution and sonicate for 1 h to obtain magnetic sepiolite fiber dispersion; mix 1000 mL of magnetic sepiolite fiber dispersion and 1000 mL of 5 mg / mL modified graphene oxide dispersion evenly, add 5 g of ascorbic acid, stir evenly, and reduce at 75℃ for 30 min to obtain composite hydrogel; place the composite hydrogel in a refrigerator, freeze at -18℃ for 6 h, thaw at room temperature for 2 h, wash with deionized water and dry to obtain composite aerogel;
[0038] Step S2: Combine 10 parts of composite aerogel, 15 parts of flame retardant, 20 parts of film-forming agent, 0.3 parts of dispersant, 0.2 parts of defoamer, 0.1 parts of thickener and 30 parts of deionized water to obtain a microwave absorbing coating;
[0039] Step S3: Add 100 parts of expanded polystyrene beads to 65 parts of microwave absorbing coating, stir evenly and dry, then pass steam into the molding machine for heating. The steam pressure is 0.1 MPa and the heating time is 60 min to obtain a flame-retardant microwave absorbing material based on polystyrene foam.
[0040] The preparation method of magnetic sepiolite fibers is as follows:
[0041] Iron carbonyl, nickel tetracarbonyl, and xylene were mixed evenly at a mass ratio of 3:1 to obtain 50 mL of 40 wt% magnetic metal solution. Ten parts of dried sepiolite fiber were added, nitrogen gas was introduced, and a pyrolysis reaction was carried out. After cooling to room temperature, the material was discharged, washed with anhydrous ethanol, filtered, and dried to obtain magnetic sepiolite fiber. The pyrolysis reaction temperature was controlled by a three-stage programmed heating method: the first stage was from room temperature to 100℃ at a heating rate of 0.4℃ / min; the second stage was from 100℃ to 120℃ at a heating rate of 0.03℃ / min; and the third stage was from 120℃ to 150℃ at a heating rate of 0.05℃ / min.
[0042] The preparation method of modified graphene oxide is as follows:
[0043] Five parts of graphene oxide were dispersed in a mixed solution of 75 parts anhydrous ethanol and 15 parts deionized water. Five parts of 3-chloropropyltriethoxysilane were added, and the mixture was stirred at 60°C for 6 hours. After filtration, washing, and drying, silanized graphene oxide was obtained. 20 mL of acetonitrile and 0.5 g of N-octylpyridine bis(trifluoromethanesulfonyl)imide salt were mixed evenly to obtain an ionic liquid solution. Five parts of silanized graphene oxide were dispersed in 20 mL of the ionic liquid solution and magnetically stirred under reflux at 80°C for 12 hours to obtain modified graphene oxide.
[0044] Example 2: A method for preparing a flame-retardant microwave absorbing material based on polystyrene foam, comprising the following processes:
[0045] Step S1: Disperse 10 parts of magnetic sepiolite fiber into 1500 mL of 0.1 wt% sodium dodecylbenzenesulfonate solution and sonicate for 1.5 h to obtain a magnetic sepiolite fiber dispersion; mix 1000 mL of magnetic sepiolite fiber dispersion and 2000 mL of 8 mg / mL modified graphene oxide dispersion evenly, add 48 parts of ascorbic acid, stir evenly, and reduce at 80℃ for 50 min to obtain a composite hydrogel; place the composite hydrogel in a refrigerator, freeze at -18℃ for 12 h, thaw at room temperature for 6 h, wash with deionized water and dry to obtain a composite aerogel;
[0046] Step S2: Combine 15 parts of composite aerogel, 20 parts of flame retardant, 30 parts of film-forming agent, 0.4 parts of dispersant, 0.3 parts of defoamer, 0.2 parts of thickener and 35 parts of deionized water to obtain a microwave absorbing coating;
[0047] Step S3: Add 100 parts of expanded polystyrene beads to 75 parts of microwave absorbing coating, stir evenly and dry, then pass steam into the molding machine for heating. The steam pressure is 0.2 MPa and the heating time is 40 min to obtain a flame-retardant microwave absorbing material based on polystyrene foam.
[0048] The preparation method of magnetic sepiolite fibers is as follows:
[0049] Iron carbonyl, nickel tetracarbonyl, and xylene were mixed evenly at a mass ratio of 3:1.5 to obtain 80 mL of 50 wt% magnetic metal solution. Ten parts of dried sepiolite fiber were added, and nitrogen gas was introduced to carry out the pyrolysis reaction. After cooling to room temperature, the material was discharged, washed with anhydrous ethanol, filtered, and dried to obtain magnetic sepiolite fiber. The pyrolysis reaction temperature was controlled by a three-stage programmed heating method: the first stage was from room temperature to 120℃ at a heating rate of 0.6℃ / min; the second stage was from 120℃ to 150℃ at a heating rate of 0.05℃ / min; and the third stage was from 150℃ to 180℃ at a heating rate of 0.2℃ / min.
[0050] The preparation method of modified graphene oxide is as follows:
[0051] Sixteen parts of graphene oxide were dispersed in a mixed solution of 250 parts of anhydrous ethanol and 60 parts of deionized water. 32 parts of 3-chloropropyltriethoxysilane were added, and the mixture was stirred at 65°C for 10 h. After filtration, washing, and drying, silanized graphene oxide was obtained. 72 mL of acetonitrile and 1.6 g of N-octylpyridine bis(trifluoromethanesulfonyl)imide salt were mixed evenly to obtain an ionic liquid solution. Sixteen parts of silanized graphene oxide were dispersed in 72 mL of the ionic liquid solution and magnetically stirred under reflux at 82°C for 18 h to obtain modified graphene oxide.
[0052] Example 3: A method for preparing a flame-retardant microwave absorbing material based on polystyrene foam, comprising the following processes:
[0053] Step S1: Disperse 5 parts of magnetic sepiolite fiber into 1000 mL of 0.5 wt% sodium dodecylbenzenesulfonate solution and sonicate for 2 h to obtain magnetic sepiolite fiber dispersion; mix 1000 mL of magnetic sepiolite fiber dispersion and 3000 mL of 10 mg / mL modified graphene oxide dispersion evenly, add 150 parts of ascorbic acid, stir evenly, and reduce at 85℃ for 60 min to obtain composite hydrogel; place the composite hydrogel in a refrigerator, freeze at -18℃ for 12 h, thaw at room temperature for 6 h, wash with deionized water and dry to obtain composite aerogel;
[0054] Step S2: Combine 20 parts of composite aerogel, 30 parts of flame retardant, 35 parts of film-forming agent, 0.5 parts of dispersant, 0.4 parts of defoamer, 0.3 parts of thickener and 40 parts of deionized water to obtain a microwave absorbing coating;
[0055] Step S3: Add 100 parts of expanded polystyrene beads to 85 parts of microwave absorbing coating, stir evenly and dry, then pass steam into the molding machine for heating. The steam pressure is 0.3 MPa and the heating time is 30 min to obtain a flame-retardant microwave absorbing material based on polystyrene foam.
[0056] The preparation method of magnetic sepiolite fibers is as follows:
[0057] Iron carbonyl, nickel tetracarbonyl, and xylene were mixed evenly at a mass ratio of 3:2 to obtain 50 mL of a 60 wt% magnetic metal solution. Five parts of dried sepiolite fiber were added, and nitrogen gas was introduced to carry out the pyrolysis reaction. After cooling to room temperature, the solution was discharged, washed with anhydrous ethanol, filtered, and dried to obtain magnetic sepiolite fiber. The pyrolysis reaction temperature was controlled by a three-stage programmed heating method: the first stage was from room temperature to 150 °C at a heating rate of 0.8 °C / min; the second stage was from 150 °C to 200 °C at a heating rate of 0.20 °C / min; and the third stage was from 200 °C to 220 °C at a heating rate of 0.40 °C / min.
[0058] The preparation method of modified graphene oxide is as follows:
[0059] 30 parts of graphene oxide were dispersed in a mixed solution of 600 parts of anhydrous ethanol and 150 parts of deionized water. 90 parts of 3-chloropropyltriethoxysilane were added, and the mixture was stirred at 70°C for 12 h. After filtration, washing, and drying, silanized graphene oxide was obtained. 150 mL of acetonitrile and 3 g of N-octylpyridine bis(trifluoromethanesulfonyl)imide salt were mixed evenly to obtain an ionic liquid solution. 30 parts of silanized graphene oxide were dispersed in 150 mL of the ionic liquid solution and magnetically stirred under reflux at 85°C for 24 h to obtain modified graphene oxide.
[0060] Comparative Example 1: A method for preparing a flame-retardant microwave absorbing material based on polystyrene foam, comprising the following processes:
[0061] Step S1: Add 48 parts of ascorbic acid to 2000 mL of 8 mg / mL modified graphene oxide dispersion, stir evenly, reduce at 80℃ for 50 min to obtain modified graphene oxide hydrogel; place the modified graphene oxide hydrogel in a refrigerator, freeze at -18℃ for 12 h, thaw at room temperature for 6 h, wash with deionized water and dry to obtain modified graphene oxide aerogel.
[0062] Step S2: Mix 15 parts of modified graphene oxide aerogel, 20 parts of flame retardant, 30 parts of film-forming agent, 0.4 parts of dispersant, 0.3 parts of defoamer, 0.2 parts of thickener and 35 parts of deionized water to obtain a microwave absorbing coating.
[0063] Step S3: Add 100 parts of expanded polystyrene beads to 75 parts of microwave absorbing coating, stir evenly and dry, then pass steam into the molding machine for heating. The steam pressure is 0.2 MPa and the heating time is 40 min to obtain a flame-retardant microwave absorbing material based on polystyrene foam.
[0064] Comparative Example 1 is based on Example 2, but magnetic sepiolite fibers were not introduced in Comparative Example 1. The remaining process steps and reaction parameters are the same as in Example 2.
[0065] Comparative Example 2: A method for preparing a flame-retardant microwave absorbing material based on polystyrene foam, comprising the following processes:
[0066] Step S1: Disperse 10 parts of magnetic sepiolite fiber into 1500 mL of 0.1 wt% sodium dodecylbenzenesulfonate solution and sonicate for 1.5 h to obtain a magnetic sepiolite fiber dispersion; mix 1000 mL of magnetic sepiolite fiber dispersion and 2000 mL of 8 mg / mL graphene oxide dispersion evenly, add 48 parts of ascorbic acid, stir evenly, and reduce at 80℃ for 50 min to obtain a composite hydrogel; place the composite hydrogel in a refrigerator, freeze at -18℃ for 12 h, thaw at room temperature for 6 h, wash with deionized water and dry to obtain a composite aerogel;
[0067] Step S2: Combine 15 parts of composite aerogel, 20 parts of flame retardant, 30 parts of film-forming agent, 0.4 parts of dispersant, 0.3 parts of defoamer, 0.2 parts of thickener and 35 parts of deionized water to obtain a microwave absorbing coating;
[0068] Step S3: Add 100 parts of expanded polystyrene beads to 75 parts of microwave absorbing coating, stir evenly and dry, then pass steam into the molding machine for heating. The steam pressure is 0.2 MPa and the heating time is 40 min to obtain a flame-retardant microwave absorbing material based on polystyrene foam.
[0069] Comparative Example 2 is based on Example 2, except that the modified graphene oxide is replaced with unmodified graphene oxide, and the remaining process steps and reaction parameters are the same as in Example 2.
[0070] Comparative Example 3: A method for preparing a flame-retardant microwave absorbing material based on polystyrene foam, comprising the following processes:
[0071] Step S1: Disperse 10 parts of sepiolite fiber into 1500 mL of 0.1 wt% sodium dodecylbenzenesulfonate solution and sonicate for 1.5 h to obtain sepiolite fiber dispersion; mix 1000 mL of sepiolite fiber dispersion and 2000 mL of 8 mg / mL modified graphene oxide dispersion evenly, add 48 parts of ascorbic acid, stir evenly, and reduce at 80℃ for 50 min to obtain composite hydrogel; place the composite hydrogel in a refrigerator, freeze at -18℃ for 12 h, thaw at room temperature for 6 h, wash with deionized water and dry to obtain composite aerogel;
[0072] Step S2: Combine 15 parts of composite aerogel, 20 parts of flame retardant, 30 parts of film-forming agent, 0.4 parts of dispersant, 0.3 parts of defoamer, 0.2 parts of thickener and 35 parts of deionized water to obtain a microwave absorbing coating;
[0073] Step S3: Add 100 parts of expanded polystyrene beads to 75 parts of microwave absorbing coating, stir evenly and dry, then pass steam into the molding machine for heating. The steam pressure is 0.2 MPa and the heating time is 40 min to obtain a flame-retardant microwave absorbing material based on polystyrene foam.
[0074] The preparation method of modified graphene oxide is as follows:
[0075] Sixteen parts of graphene oxide were dispersed in a mixed solution of 250 parts of anhydrous ethanol and 60 parts of deionized water. 32 parts of 3-chloropropyltriethoxysilane were added, and the mixture was stirred at 65°C for 10 h. After filtration, washing, and drying, silanized graphene oxide was obtained. 72 mL of acetonitrile and 1.6 g of N-octylpyridine bis(trifluoromethanesulfonyl)imide salt were mixed evenly to obtain an ionic liquid solution. Sixteen parts of silanized graphene oxide were dispersed in 72 mL of the ionic liquid solution and magnetically stirred under reflux at 82°C for 18 h to obtain modified graphene oxide.
[0076] Comparative Example 2 is based on Example 2, except that the magnetic sepiolite fibers are replaced with sepiolite fibers of the same mass, and the remaining process steps and reaction parameters are the same as in Example 2.
[0077] Experiment: Flame-retardant microwave absorbing materials based on polystyrene foam obtained in Examples 1-3 and Comparative Examples 1-3 were used to prepare samples. Their performance was tested and the test results were recorded.
[0078] 1. Limiting oxygen index test: The test was conducted in accordance with GB / T 2406.1-2008 "Determination of combustion behavior of plastics by oxygen index method"; 2. Impact strength was tested in accordance with GB / T 1043.1-2008 "Determination of impact performance of simply supported plastic beams", and the test results are shown in Table 1.
[0079] Table 1. Test results of relevant performance of flame-retardant and microwave-absorbing materials based on polystyrene foam.
[0080] Limiting oxygen index / % Impact strength (KJ / m) Example 1 32.4 0.78 Example 2 33.0 0.80 Example 3 33.8 0.83 Comparative Example 1 28.6 0.64 Comparative Example 2 31.2 0.72 Comparative Example 3 30.5 0.70
[0081] Based on the data in Table 1, the following conclusions can be clearly drawn:
[0082] Combining Examples 1-3 and Comparative Examples 1-3, it can be seen that the flame-retardant microwave absorbing material prepared by the present invention has excellent mechanical and flame-retardant properties; in Comparative Example 1, without the introduction of magnetic sepiolite fibers, the mechanical and flame-retardant properties of the material decreased uniformly; the flame-retardant and mechanical properties of the products obtained in Comparative Examples 2 and 3 both decreased, indicating that the present invention, by introducing magnetic sepiolite fibers and modified graphene oxide, has a synergistic effect, which improves the overall performance of the material.
[0083] 3. Radar absorption performance test: The flame-retardant radar absorbing materials based on polystyrene foam prepared in Examples 1-3 and Comparative Examples 1-3 were tested in accordance with GJB 2038A-2011 "Test Method for Reflectivity of Radar Radar Absorbing Materials". The results are shown in Table 2.
[0084] Table 2 Test results of microwave absorption performance of flame-retardant microwave absorbing materials based on polystyrene foam
[0085] 0.5GHz 1GHz 6GHz 10GHz 18GHz Example 1 -19.7 -28.8 -30.7 -35.8 -22.0 Example 2 -20.1 -29.5 -31.6 -37.4 -23.4 Example 3 -21.6 -31.2 -33.5 -38.7 -24.6 Comparative Example 1 -15.8 -23.7 -25.2 -31.5 -19.7 Comparative Example 2 -18.4 -26.6 -28.9 -34.2 -21.5 Comparative Example 3 -17.3 -24.5 -26.8 -33.9 -20.3
[0086] As can be seen from the test results in Table 2, the flame-retardant microwave absorbing material based on polystyrene foam prepared in this invention has excellent microwave absorption performance.
[0087] It will be apparent to those skilled in the art that the present 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 characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.
Claims
1. A method for preparing a flame-retardant microwave absorbing material based on polystyrene foam, characterized in that: Includes the following steps: Step S1: Magnetic sepiolite fibers are dispersed in sodium dodecylbenzenesulfonate solution and ultrasonically treated for 1-2 hours to obtain a magnetic sepiolite fiber dispersion; the magnetic sepiolite fiber dispersion and modified graphene oxide dispersion are mixed evenly, ascorbic acid is added, stirred evenly, and reduced at 75-85℃ for 30-60 minutes to obtain a composite hydrogel; the composite hydrogel is frozen, thawed, washed, and dried to obtain a composite aerogel; Step S2: Combine composite aerogel, flame retardant, film-forming agent, dispersant, defoamer, thickener and deionized water to obtain microwave absorbing coating; Step S3: Add expanded polystyrene beads into the microwave absorbing coating, stir evenly, dry, and mold to obtain a flame-retardant microwave absorbing material based on polystyrene foam. The preparation method of the magnetic sepiolite fiber is as follows: Carbonyl iron, tetracarbonyl nickel and xylene are mixed evenly to obtain a magnetic metal solution. Dried sepiolite fibers are added, nitrogen gas is introduced to carry out a pyrolysis reaction, the temperature is cooled to room temperature, the material is discharged, washed with anhydrous ethanol, filtered and dried to obtain magnetic sepiolite fibers. The modified graphene oxide is prepared as follows: Graphene oxide was dispersed in a mixed solution of anhydrous ethanol and deionized water, and 3-chloropropyltriethoxysilane was added. The mixture was stirred at 60-70°C for 6-12 hours. After filtration, washing, and drying, silanized graphene oxide was obtained. Acetonitrile and N-octylpyridine bis(trifluoromethanesulfonyl)imide salt were mixed evenly to obtain an ionic liquid solution. The silanized graphene oxide was dispersed in the ionic liquid solution and refluxed magnetically at 80-85°C for 12-24 hours to obtain modified graphene oxide.
2. The method for preparing a flame-retardant microwave absorbing material based on polystyrene foam according to claim 1, characterized in that: The liquid-to-solid ratio of the sodium dodecylbenzenesulfonate solution to the magnetic sepiolite fiber is (100-200) mL:1 g, and the mass fraction of the sodium dodecylbenzenesulfonate solution is 0.05-0.5%.
3. The method for preparing a flame-retardant microwave absorbing material based on polystyrene foam according to claim 1, characterized in that: The volume ratio of the magnetic sepiolite fiber dispersion to the modified graphene oxide dispersion is 1:(1-3); the concentration of the modified graphene oxide dispersion is 5-10 mg / mL, and the solvent is deionized water.
4. The method for preparing a flame-retardant microwave absorbing material based on polystyrene foam according to claim 1, characterized in that: The microwave absorbing coating comprises the following components by weight: 10-20 parts of composite aerogel, 15-30 parts of flame retardant, 20-35 parts of film-forming agent, 0.3-0.5 parts of dispersant, 0.2-0.4 parts of defoamer, 0.1-0.3 parts of thickener, and 30-40 parts of deionized water.
5. The method for preparing a flame-retardant microwave absorbing material based on polystyrene foam according to claim 1, characterized in that: The film-forming agent is a styrene-acrylic emulsion with a solid mass fraction of 45-55%.
6. The method for preparing a flame-retardant microwave absorbing material based on polystyrene foam according to claim 1, characterized in that: The flame retardant is one or a mixture of expanded graphite, ammonium polyphosphate, pentaerythritol, or aluminum hydroxide.
7. The method for preparing a flame-retardant microwave absorbing material based on polystyrene foam according to claim 1, characterized in that: The mass ratio of expanded polystyrene beads to microwave absorbing coating is 100:(65-85).
8. A flame-retardant microwave absorbing material based on polystyrene foam prepared by the preparation method according to any one of claims 1-7.