Environment-friendly high-strength expandable polystyrene and preparation method thereof
By modifying sodium-based montmorillonite and hydroxyethyl cellulose, a three-dimensional reinforcing network of modified montmorillonite and modified dispersant was constructed, which solved the problem of insufficient mechanical properties of traditional expandable polystyrene materials and realized the preparation of high-strength and environmentally friendly polystyrene materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- LIAONING LITIAN NEW MATERIAL CO LTD
- Filing Date
- 2026-04-28
- Publication Date
- 2026-05-29
Smart Images
Figure CN122103404A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to an environmentally friendly, high-strength expandable polystyrene and its preparation method. Background Technology
[0002] Expandable polystyrene (EPS) is an important foamed plastic material, widely used in building insulation, packaging cushioning, and decorative materials due to its lightweight, heat insulation, sound insulation, shock absorption, and excellent molding and processing properties. Traditional EPS is typically produced from styrene monomers through a suspension polymerization process, with low-boiling-point hydrocarbon blowing agents (such as pentane) added during or after polymerization. However, with the expansion of application areas and increasingly stringent environmental requirements, traditional EPS materials have gradually revealed significant shortcomings in mechanical properties. Conventional EPS has relatively low tensile strength and impact resistance, limiting its use in applications requiring high load-bearing capacity or impact resistance (such as heavy packaging and structural components).
[0003] Patent application CN201710349183.1 discloses expandable polystyrene and its preparation method. In the expandable polystyrene, the amount of graphene accounts for 0.2wt%-1wt% of the total weight of styrene monomers before polymerization. The expandable polystyrene is pressed into sheets to obtain foam boards. The flame retardant rating of the foam boards can reach B1 level, the thermal conductivity value is reduced from the original 0.039-0.042 W / (m·K) to 0.030-0.034 W / (m·K), and the pull-out performance is increased from the original 90 kPa to 260 kPa. However, in suspension polymerization systems, graphene sheets are prone to agglomeration and recombination. Uneven dispersion can become stress concentration points, which can impair material properties. Patent application number CN202511506654.6 provides an environmentally friendly expandable polystyrene bead and its preparation process, belonging to the field of foaming material technology. The preparation process includes the following steps: S1, injecting 65.28g of deionized water into a reaction vessel, stirring, adding 0.13g of dispersant and 0.16g of composite stabilizer, dispersing for 20min, adding 31.95g of styrene monomer and 0.3g of composite initiator, and then adding pentane and silica fiber bundle composite to obtain a basic solution. The process involves several steps: S1, S2, S3, S4, S5, S6, S7, S8, S9, S1, S2, S3, S4, S8, S9, S1, S2, S3, S4, S2, S3, S4, S3, S4, S4, S5, S6, S7, S8, S9, S1, S2, S3, S4 ...
[0004] Therefore, developing an expandable polystyrene that combines high strength, good processability, and environmental friendliness to meet the needs of high-end packaging, green building, and other fields has become an urgent problem to be solved in this technology field. Summary of the Invention
[0005] To address the aforementioned problems, this invention provides an environmentally friendly, high-strength expandable polystyrene and its preparation method. Modified montmorillonite is obtained by sequentially acid-activating sodium-based montmorillonite, modifying it with silane coupling agent KH-570, and performing a composite surface treatment with hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, and polyethylene glycol. A modified dispersant is obtained by reacting hydroxyethyl cellulose with silane coupling agent KH-570 under acidic conditions. Finally, environmentally friendly, high-strength expandable polystyrene is obtained through processes such as suspension polymerization using styrene monomer, modified montmorillonite, modified dispersant, composite initiator, and foaming agent as raw materials.
[0006] The technical solution of the present invention to solve the above problems is as follows: An environmentally friendly high-strength expandable polystyrene comprises the following raw materials in parts by weight: 90-100 parts styrene monomer, 120-150 parts deionized water, 3-5 parts modified montmorillonite, 0.3-0.8 parts modified dispersant, 0.3-0.6 parts composite initiator, and 5-6 parts foaming agent; The preparation method of the modified montmorillonite is as follows: Step 1: Add sodium-based montmorillonite to deionized water at 55-65℃ and stir for 110-130 min. Let it stand and swell for 11.5-12.5 h. Then raise the temperature to 65-75℃, adjust the pH to 4.5-5.0, stir for 110-130 min, add aluminum sulfate aqueous solution, and continue stirring for 55-65 min. Then add citric acid and stir at 55-65℃ for 25-35 min. After post-treatment, activated montmorillonite is obtained. Step 2: Dissolve silane coupling agent KH-570 in anhydrous ethanol, add deionized water and glacial acetic acid, stir at room temperature for 25-35 min, then add activated montmorillonite, ultrasonically disperse for 25-35 min, heat to 70-75℃, stir and react under an inert atmosphere for 4-6 h, and obtain silane-modified montmorillonite after post-treatment. Step 3: Disperse the silane-modified montmorillonite in deionized water at 75-85℃ and ultrasonically disperse for 55-65 min. Then add hexadecyltrimethylammonium bromide and stir at 75-85℃ for 110-130 min. Then cool down to 65-75℃, add sodium dodecyl sulfonate and stir for 55-65 min. Finally, add polyethylene glycol and continue stirring for 55-65 min. After post-treatment, the modified montmorillonite is obtained.
[0007] Further, in step 1, the mass ratio of sodium montmorillonite, deionized water, aluminum sulfate aqueous solution, and citric acid is 100:1990-2010:25-50:2-3, and the mass fraction of aluminum sulfate aqueous solution is 1.8-2.2%.
[0008] Further, in step 2, the mass ratio of silane coupling agent KH-570, anhydrous ethanol, deionized water, glacial acetic acid, and activated montmorillonite is 10-12:470-480:20-30:2-3:100.
[0009] Further, in step 3, the mass ratio of silane-modified montmorillonite, deionized water, hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, and polyethylene glycol is 100:1490-1510:35-40:3-5:4.5-5.5.
[0010] Further, the modified dispersant is prepared as follows: hydroxyethyl cellulose is added to anhydrous ethanol and stirred at room temperature for 25-35 min, then deionized water is added and stirred for another 55-65 min, the pH is adjusted to 4.5-5.0, silane coupling agent KH-570 is added, and the mixture is stirred at room temperature for 35-45 min, then the temperature is raised to 60-65℃ and stirred for 3-4 h. The modified dispersant is obtained after post-treatment.
[0011] Furthermore, the mass ratio of the hydroxyethyl cellulose, anhydrous ethanol, deionized water, and silane coupling agent KH-570 is 100:490-510:25-35:8-10.
[0012] Furthermore, the composite initiator is composed of benzoyl peroxide and tert-butyl peroxide in a mass ratio of 1:0.9-1.1.
[0013] Furthermore, the foaming agent is a mixture of n-pentane and isopentane in a mass ratio of 1:0.9-1.1.
[0014] The above-mentioned method for preparing environmentally friendly high-strength expandable polystyrene includes the following steps: Step (1): Add the modified dispersant to deionized water, stir to dissolve, then add the modified montmorillonite, and ultrasonically disperse for 25-35 minutes to obtain a suspension; Step (2): Mix the styrene monomer and the composite initiator, stir to dissolve, and then add to the suspension obtained in step (1). Heat to 80-85℃, stir and react for 4-6 hours, then heat to 90-95℃ and continue to react for 2-3 hours to obtain the polymer product. Step (3): Cool the polymerization product to 20-25℃, add foaming agent, stir for 30-60 minutes, then heat to 85-95℃ and maintain for 1-2 hours. After post-treatment, the product is obtained.
[0015] The present invention has the following beneficial effects: The modified montmorillonite and modified dispersant prepared in this invention play a core role in enhancing and stabilizing the system, and their synergistic effect is the key to comprehensively improving the mechanical properties of expandable polystyrene. This invention first chemically modifies montmorillonite. Firstly, mild acid activation and trace amounts of aluminum sulfate are used to introduce numerous hydroxyl active sites at the edges of the montmorillonite. Free aluminum ions are then removed by citric acid chelation washing, creating a reaction platform for subsequent modification. Subsequently, glacial acetic acid is used to adjust the pH in an ethanol / water system, promoting the complete hydrolysis of the silane coupling agent KH-570 and its condensation reaction with the hydroxyl groups on the montmorillonite surface. This covalently grafts active double bonds onto the montmorillonite surface and interlayer edges, allowing the inorganic filler montmorillonite to be tightly connected to the polystyrene molecular chain network through chemical bonds, fundamentally solving the problem of weak interfacial bonding between traditional fillers and the matrix. Finally, by sequentially adding hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, and polyethylene glycol, a gradient structure with an "inner oleophilic and outer hydrophilic" characteristic is constructed. This ensures stable dispersion of montmorillonite in the aqueous suspension polymerization system while also exhibiting excellent compatibility with styrene droplets entering the oil phase, achieving uniform dispersion of montmorillonite in the polystyrene matrix. Furthermore, hydroxyethyl cellulose was modified by adjusting the pH in an anhydrous ethanol / water mixture with glacial acetic acid, which caused the silane coupling agent KH-570 to undergo a condensation reaction with the hydroxyl groups on the hydroxyethyl cellulose molecular chain. This introduced hydrophobic silane segments and carbon-carbon double bonds that could participate in free radical polymerization into the originally hydrophilic dispersant molecular chain. This modified dispersant can effectively maintain the stable dispersion of styrene droplets in the early stage of suspension polymerization, ensuring uniform particle size. In the later stage of polymerization, the grafted carbon-carbon double bonds undergo copolymerization with styrene, anchoring the dispersant to the polystyrene molecular chain and avoiding the problem of traditional dispersants being easily washed away in the washing process. More importantly, both the modified montmorillonite and the modified dispersant have KH-570-derived active double bonds and hydrophobic segments grafted onto their surfaces. They exhibit good compatibility and can form physical cross-linking points through hydrogen bonds or segment entanglement. In the polymerization reaction, they jointly participate in the free radical polymerization of styrene, thereby constructing a three-dimensional reinforcing network in the polystyrene matrix with modified montmorillonite as rigid nodes and modified dispersant as flexible links. This network structure can simultaneously leverage the high rigidity of montmorillonite and the toughening effect of the dispersant. Under tensile stress, the flexible segments of the dispersant orient and stretch, effectively transferring stress. Under impact load, energy is absorbed through interfacial debonding and segment movement. Under compressive stress, the rigid network effectively resists deformation, ultimately resulting in a balanced and significant improvement in the tensile strength, flexural strength, impact strength, and compressive strength of the material.
[0016] The technical system constructed in this invention involves the synergistic and indispensable cooperation of all raw material components, which together achieve the preparation of environmentally friendly, high-strength expandable polystyrene. Styrene monomer, as the core monomer of the polymerization reaction, provides the basic framework for the polystyrene matrix. Modified montmorillonite, as the core reinforcing filler, participates in the polymerization reaction through its surface active double bonds, firmly embedding itself into the polystyrene molecular chain via chemical bonding. Its gradient structure of "oil-loving inside and hydrophilic outside" achieves uniform dispersion, fully leveraging the rigidity-reinforcing advantages of inorganic nanofillers. The modified dispersant not only fulfills the basic functions of traditional dispersants in maintaining the stability of the suspension system and ensuring uniform bead size, but also participates in the polymerization reaction through its grafted active double bonds, anchoring itself to the polystyrene molecular chain and forming a bond with the modified montmorillonite through hydrogen bonds and chain segment entanglement. The three-dimensional reinforcing network plays multiple roles in the material, simultaneously providing dispersion stabilization, interfacial bridging, and toughening reinforcement. The composite initiator, composed of benzoyl peroxide and tert-butyl peroxide in a specific ratio, works synergistically during polymerization. The low-temperature initiator ensures a smooth start-up of the polymerization reaction, while the high-temperature initiator guarantees complete polymerization in the later stages, effectively controlling the polymerization rate and reducing residual monomer content, thus providing ideal reaction conditions for the formation of the three-dimensional reinforcing network. The pentane-based blowing agent, using a specific ratio of n-pentane and isopentane, can dissolve uniformly in polystyrene beads at suitable temperatures, providing excellent foaming performance for subsequent foaming molding. The precise synergistic effect among the above raw material components, and this systematic design from microstructure to macroscopic properties, enables the expandable polystyrene prepared by this invention to comprehensively improve tensile strength, flexural strength, impact strength, and compressive strength, while also possessing excellent environmental performance and process stability, forming a complete and inseparable technical solution. Attached Figure Description
[0017] Figure 1 The graph shows the test results of tensile strength, flexural strength, impact strength, and compressive strength for Examples 1-4 and Comparative Examples 1-4. Detailed Implementation
[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0019] All raw materials used in the following examples are commercially available products. Sodium montmorillonite has a moisture content of ≤0.01%, a purity of 95%, and a particle size of 1250 mesh; it was sourced from Lingshou County Tuolin Mineral Products Processing Plant. Polyethylene glycol is PEG1000 with an active ingredient content of 99%; it was sourced from Hubei Xinjiecheng Chemical Technology Co., Ltd. Hydroxyethyl cellulose has an active ingredient content of 99%; it was sourced from Hubei Xinghengye Technology Co., Ltd.
[0020] Example 1
[0021] An environmentally friendly high-strength expandable polystyrene comprises the following raw materials in parts by weight: 90 parts styrene monomer, 120 parts deionized water, 3 parts modified montmorillonite, 0.3 parts modified dispersant, 0.3 parts composite initiator, and 5 parts foaming agent. The preparation method of the modified montmorillonite is as follows: Step S1: Add sodium montmorillonite to deionized water at 60℃, stir at 400 rpm for 120 min, let it stand to swell for 12 h, then heat to 70℃, add 5% sulfuric acid solution to adjust the pH to 4.5-5.0, stir at 300 rpm for 120 min, then add aluminum sulfate aqueous solution, continue stirring for 60 min, then add citric acid, stir at 60℃ for 30 min, then centrifuge at 4000 rpm for 15 min, wash with deionized water until pH 6.5-7.5, then vacuum dry at 60℃ for 24 h, grind through a 300 mesh sieve to obtain activated montmorillonite, wherein the mass ratio of sodium montmorillonite, deionized water, aluminum sulfate aqueous solution, and citric acid is 100:2000:40:2.5, and the mass fraction of aluminum sulfate aqueous solution is 2%; Step S2: Dissolve silane coupling agent KH-570 in anhydrous ethanol, add deionized water and glacial acetic acid, stir at room temperature for 30 min, then add activated montmorillonite, ultrasonically disperse for 30 min (ultrasonic power 400 W, frequency 40 kHz), heat to 73℃, stir and react for 5 h under nitrogen atmosphere, then centrifuge at 4000 rpm for 15 min, wash 4 times with anhydrous ethanol, then vacuum dry at 40℃ for 24 h, grind through a 300-mesh sieve to obtain silane-modified montmorillonite, wherein the mass ratio of silane coupling agent KH-570, anhydrous ethanol, deionized water, glacial acetic acid, and activated montmorillonite is 11:475:25:2.5:100; Step S3: Disperse silane-modified montmorillonite in deionized water at 80°C, and ultrasonically disperse for 60 min (ultrasonic power 400 W, frequency 40 kHz). Add hexadecyltrimethylammonium bromide, stir at 80°C for 120 min, then cool to 70°C, add sodium dodecyl sulfonate, and stir for 60 min. Finally, add polyethylene glycol and continue stirring for 60 min. Then centrifuge at 4000 rpm for 15 min, wash with deionized water at 60°C until no bromide ions are found, and no white precipitate is detected by silver nitrate. Vacuum dry at 40°C for 24 h, grind through a 300-mesh sieve to obtain modified montmorillonite. The mass ratio of silane-modified montmorillonite, deionized water, hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, and polyethylene glycol is 100:1500:37:4:5.
[0022] The modified dispersant is prepared as follows: Hydroxyethyl cellulose is added to anhydrous ethanol and stirred at room temperature for 30 min. Then, deionized water is added and stirring is continued for 60 min. Glacial acetic acid is added to adjust the pH to 4.5-5.0. Silane coupling agent KH-570 is added and stirred at room temperature for 40 min. Then, the temperature is raised to 63℃ and stirred for 3.5 h. Part of the ethanol is removed by vacuum distillation. Then, the mixture is cooled to room temperature and centrifuged at 4000 rpm for 15 min. The mixture is washed three times with anhydrous ethanol, dried under vacuum at 50℃ for 12 h, and ground through a 200-mesh sieve to obtain the modified dispersant. The mass ratio of hydroxyethyl cellulose, anhydrous ethanol, deionized water, and silane coupling agent KH-570 is 100:500:30:9.
[0023] The composite initiator is composed of benzoyl peroxide and tert-butyl peroxide in a mass ratio of 1:0.9, and the foaming agent is a mixture of n-pentane and isopentane in a mass ratio of 1:0.9.
[0024] The above-mentioned method for preparing environmentally friendly high-strength expandable polystyrene includes the following steps: Step (1): Add the modified dispersant to deionized water, stir to dissolve, then add the modified montmorillonite, and ultrasonically disperse for 25 minutes to obtain a suspension. The ultrasonic power is 400W and the frequency is 40KHz. Step (2): Mix the styrene monomer and the composite initiator, stir to dissolve, and then add to the suspension obtained in step (1). Heat to 80°C, stir and react for 4 hours, then heat to 90°C and continue to react for 2 hours to obtain the polymerization product. Step (3): Cool the polymerization product to 20°C, add foaming agent, stir for 30 min, then heat to 85°C, keep for 1 h, centrifuge at 4000 rpm for 15 min, vacuum dry at 40°C to constant weight, and grind through a 20-mesh sieve to obtain the product.
[0025] Example 2
[0026] An environmentally friendly high-strength expandable polystyrene comprises the following raw materials in parts by weight: 100 parts styrene monomer, 150 parts deionized water, 5 parts modified montmorillonite, 0.8 parts modified dispersant, 0.6 parts composite initiator, and 6 parts foaming agent. The preparation method of the modified montmorillonite and the preparation method of the modified dispersant are the same as in Example 1.
[0027] The composite initiator is composed of benzoyl peroxide and tert-butyl peroxide in a mass ratio of 1:1.1, and the foaming agent is a mixture of n-pentane and isopentane in a mass ratio of 1:1.1.
[0028] The above-mentioned method for preparing environmentally friendly high-strength expandable polystyrene includes the following steps: Step (1): Add the modified dispersant to deionized water, stir to dissolve, then add the modified montmorillonite, and ultrasonically disperse for 35 minutes to obtain a suspension. The ultrasonic power is 400W and the frequency is 40KHz. Step (2): Mix the styrene monomer and the composite initiator, stir to dissolve, and then add to the suspension obtained in step (1). Heat to 85°C, stir and react for 6 hours, then heat to 95°C and continue to react for 3 hours to obtain the polymerization product. Step (3): Cool the polymerization product to 25°C, add foaming agent, stir for 60 min, then heat to 95°C and keep for 2 h, centrifuge at 4000 rpm for 15 min, vacuum dry at 40°C to constant weight, and grind through a 20-mesh sieve to obtain the product.
[0029] Example 3
[0030] An environmentally friendly high-strength expandable polystyrene comprises the following raw materials in parts by weight: 95 parts styrene monomer, 130 parts deionized water, 4 parts modified montmorillonite, 0.5 parts modified dispersant, 0.4 parts composite initiator, and 5.5 parts foaming agent. The preparation method of the modified montmorillonite and the preparation method of the modified dispersant are the same as in Example 1.
[0031] The composite initiator is composed of benzoyl peroxide and tert-butyl peroxide in a mass ratio of 1:1, and the foaming agent is a mixture of n-pentane and isopentane in a mass ratio of 1:1.
[0032] The above-mentioned method for preparing environmentally friendly high-strength expandable polystyrene includes the following steps: Step (1): Add the modified dispersant to deionized water, stir to dissolve, then add the modified montmorillonite, and ultrasonically disperse for 30 minutes to obtain a suspension. The ultrasonic power is 400W and the frequency is 40KHz. Step (2): Mix the styrene monomer and the composite initiator, stir to dissolve, and then add to the suspension obtained in step (1). Heat to 83°C, stir and react for 5 hours, then heat to 92°C and continue to react for 2.5 hours to obtain the polymerization product. Step (3): Cool the polymerization product to 23°C, add foaming agent, stir for 45 min, then heat to 90°C and maintain for 1.5 h, centrifuge at 4000 rpm for 15 min, vacuum dry at 40°C to constant weight, and grind through a 20-mesh sieve to obtain the final product.
[0033] Example 4
[0034] An environmentally friendly high-strength expandable polystyrene comprises the following raw materials in parts by weight: 95 parts styrene monomer, 130 parts deionized water, 4 parts modified montmorillonite, 0.5 parts modified dispersant, 0.4 parts composite initiator, and 5.5 parts foaming agent. The preparation method of the modified montmorillonite is as follows: Step S1: Add sodium montmorillonite to deionized water at 55℃, stir at 400 rpm for 110 min, let it stand and swell for 11.5 h, then heat to 65℃, add 5% sulfuric acid solution to adjust pH to 4.5-5.0, stir at 300 rpm for 110 min, then add aluminum sulfate aqueous solution, continue stirring for 55 min, then add citric acid, stir at 55℃ for 25 min, then centrifuge at 4000 rpm for 15 min, wash with deionized water until pH 6.5-7.5, then vacuum dry at 60℃ for 24 h, grind through a 300 mesh sieve to obtain activated montmorillonite, wherein the mass ratio of sodium montmorillonite, deionized water, aluminum sulfate aqueous solution, and citric acid is 100:1990:25:2, and the mass fraction of aluminum sulfate aqueous solution is 1.8%; Step S2: Dissolve silane coupling agent KH-570 in anhydrous ethanol, add deionized water and glacial acetic acid, stir at room temperature for 25 min, then add activated montmorillonite, ultrasonically disperse for 25 min (ultrasonic power 400 W, frequency 40 kHz), heat to 70℃, stir and react for 4 h under nitrogen atmosphere, then centrifuge at 4000 rpm for 15 min, wash 4 times with anhydrous ethanol, then vacuum dry at 40℃ for 24 h, grind through a 300-mesh sieve to obtain silane-modified montmorillonite, wherein the mass ratio of silane coupling agent KH-570, anhydrous ethanol, deionized water, glacial acetic acid, and activated montmorillonite is 10:470:20:2:100; Step S3: Disperse silane-modified montmorillonite in deionized water at 75°C, and ultrasonically disperse for 55 min (ultrasonic power 400 W, frequency 40 kHz). Add hexadecyltrimethylammonium bromide, stir at 75°C for 110 min, then cool to 65°C, add sodium dodecyl sulfonate, and stir for 55 min. Finally, add polyethylene glycol and continue stirring for 55 min. Then centrifuge at 4000 rpm for 15 min, wash with deionized water at 60°C until no bromide ions are found, and no white precipitate is detected by silver nitrate. Vacuum dry at 40°C for 24 h, grind through a 300-mesh sieve to obtain modified montmorillonite. The mass ratio of silane-modified montmorillonite, deionized water, hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, and polyethylene glycol is 100:1490:35:3:4.5.
[0035] The modified dispersant is prepared as follows: Hydroxyethyl cellulose is added to anhydrous ethanol and stirred at room temperature for 25 min. Then, deionized water is added and stirring is continued for 55 min. Glacial acetic acid is added to adjust the pH to 4.5-5.0. Silane coupling agent KH-570 is added and stirred at room temperature for 35 min. Then, the temperature is raised to 60℃ and stirred for 3 h. Part of the ethanol is removed by vacuum distillation. Then, the mixture is cooled to room temperature and centrifuged at 4000 rpm for 15 min. The mixture is washed three times with anhydrous ethanol, dried under vacuum at 50℃ for 12 h, and ground through a 200-mesh sieve to obtain the modified dispersant. The mass ratio of hydroxyethyl cellulose, anhydrous ethanol, deionized water, and silane coupling agent KH-570 is 100:490:25:8.
[0036] The composite initiator is composed of benzoyl peroxide and tert-butyl peroxide in a mass ratio of 1:1, and the foaming agent is a mixture of n-pentane and isopentane in a mass ratio of 1:1.
[0037] The preparation method of the above-mentioned environmentally friendly high-strength expandable polystyrene is the same as that in Example 3.
[0038] Comparative Example 1
[0039] An environmentally friendly high-strength expandable polystyrene comprises the following raw materials in parts by weight: 90 parts styrene monomer, 120 parts deionized water, 1 part modified montmorillonite, 0.1 parts modified dispersant, 0.1 parts composite initiator, and 5 parts foaming agent. The preparation method of the modified montmorillonite is as follows: Step S1: Add sodium montmorillonite to deionized water at 60℃, stir at 400 rpm for 120 min, let it stand to swell for 5 h, then heat to 70℃, stir at 300 rpm for 120 min, add aluminum sulfate aqueous solution, continue stirring for 60 min, then add citric acid, stir at 60℃ for 30 min, then centrifuge at 4000 rpm for 15 min, wash with deionized water until pH 6.5-7.5, then vacuum dry at 60℃ for 24 h, grind through a 300-mesh sieve to obtain activated montmorillonite, wherein the mass ratio of sodium montmorillonite, deionized water, aluminum sulfate aqueous solution, and citric acid is 100:2000:10:2.5, and the mass fraction of aluminum sulfate aqueous solution is 2%; Step S2: Dissolve silane coupling agent KH-570 in anhydrous ethanol, add deionized water and glacial acetic acid, stir at room temperature for 30 min, then add activated montmorillonite, ultrasonically disperse for 30 min (ultrasonic power 400 W, frequency 40 kHz), stir and react for 5 h, then centrifuge at 4000 rpm for 15 min, wash 4 times with anhydrous ethanol, then vacuum dry at 40℃ for 24 h, grind through a 300-mesh sieve to obtain silane-modified montmorillonite, wherein the mass ratio of silane coupling agent KH-570, anhydrous ethanol, deionized water, glacial acetic acid and activated montmorillonite is 1:475:25:2.5:100; Step S3: Disperse silane-modified montmorillonite in deionized water at 80°C, and ultrasonically disperse for 60 min (ultrasonic power 400 W, frequency 40 kHz). Add hexadecyltrimethylammonium bromide, stir at 50°C for 120 min, then cool to 70°C, add sodium dodecyl sulfonate, and stir for 60 min. Finally, add polyethylene glycol and continue stirring for 20 min. Then centrifuge at 4000 rpm for 15 min, wash with deionized water at 60°C until no bromide ions are found, and no white precipitate is detected by silver nitrate. Vacuum dry at 40°C for 24 h, grind through a 300-mesh sieve to obtain modified montmorillonite. The mass ratio of silane-modified montmorillonite, deionized water, hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, and polyethylene glycol is 100:1500:10:1:5.
[0040] The modified dispersant is prepared as follows: Hydroxyethyl cellulose is added to anhydrous ethanol and stirred at room temperature for 30 min. Then, deionized water is added and stirred for another 60 min. Then, silane coupling agent KH-570 is added and stirred at room temperature for 10 min. The temperature is then raised to 63°C and stirred for 3.5 h. Part of the ethanol is removed by vacuum distillation. The mixture is then cooled to room temperature and centrifuged at 4000 rpm for 15 min. The mixture is washed three times with anhydrous ethanol, dried under vacuum at 50°C for 12 h, and ground through a 200-mesh sieve to obtain the modified dispersant. The mass ratio of hydroxyethyl cellulose, anhydrous ethanol, deionized water, and silane coupling agent KH-570 is 100:500:30:5.
[0041] The composite initiator is composed of benzoyl peroxide and tert-butyl peroxide in a mass ratio of 1:0.5, and the foaming agent is a mixture of n-pentane and isopentane in a mass ratio of 1:0.5.
[0042] The above-mentioned method for preparing environmentally friendly high-strength expandable polystyrene includes the following steps: Step (1): Add the modified dispersant to deionized water, stir to dissolve, then add the modified montmorillonite, and ultrasonically disperse for 25 minutes to obtain a suspension. The ultrasonic power is 400W and the frequency is 40KHz. Step (2): Mix the styrene monomer and the composite initiator, stir to dissolve, and then add to the suspension obtained in step (1). Heat to 50°C, stir and react for 4 hours, then heat to 70°C and continue to react for 2 hours to obtain the polymer product. Step (3): Cool the polymerization product to 20°C, add foaming agent, stir for 30 min, then heat to 150°C, keep for 1 h, centrifuge at 4000 rpm for 15 min, vacuum dry at 40°C to constant weight, and grind through a 20-mesh sieve to obtain the product.
[0043] Comparative Example 2
[0044] An environmentally friendly, high-strength expandable polystyrene is described, in which modified montmorillonite is replaced with commercially available montmorillonite, and the rest is the same as in Example 1.
[0045] Comparative Example 3
[0046] An environmentally friendly, high-strength expandable polystyrene is described, in which the modified dispersant is replaced with commercially available hydroxyethyl cellulose, and the rest is the same as in Example 1.
[0047] Comparative Example 4
[0048] An environmentally friendly, high-strength expandable polystyrene is described, in which modified montmorillonite is replaced with commercially available montmorillonite, and the modified dispersant is replaced with commercially available hydroxyethyl cellulose, with the rest being the same as in Example 1.
[0049] Performance testing Before conducting the following tests, the environmentally friendly high-strength expandable polystyrene prepared in Examples 1-4 and Comparative Examples 1-4 was first prepared into polystyrene boards. Pre-foaming was then carried out by saturated steam heating at 100°C and 0.1 MPa. The boards were then cured at room temperature for 24 hours and then shaped using a board forming machine at 0.2 MPa. After cooling to room temperature, the sample size was determined according to the test requirements.
[0050] Mechanical properties: Tensile strength was tested according to GB / T 9641-2025 "Test Method for Tensile Properties of Rigid Foamed Plastics"; flexural strength was tested according to GB / T 8812.2-2007 "Determination of Flexural Properties of Rigid Foamed Plastics Part 2: Determination of Flexural Strength and Apparent Flexural Modulus"; impact strength was tested according to GB / T 1843-2008 "Determination of Cantilever Beam Impact Strength of Plastics", i.e., cantilever beam notched impact strength, with a notch of type A; compressive strength was tested according to GB / T 8813-2020 "Determination of Compressive Properties of Rigid Foamed Plastics". Test results are shown in Table 1 and... Figure 1 It can be known that...
[0051] Table 1 Performance Test Results
[0052] From Table 1 and Figure 1 It can be seen that the mechanical properties of Comparative Example 1 decreased compared with the Example. The reason is that the amount of raw materials, the modification process and the preparation process all deviated from the optimal parameters, which caused the modified montmorillonite and the modified dispersant to fail to function properly. In addition, the polymerization and foaming processes were abnormal, which ultimately resulted in a significant decrease in the tensile strength, flexural strength, impact strength and compressive strength of the environmentally friendly high-strength expandable polystyrene.
[0053] From Table 1 and Figure 1 As can be seen, compared with the examples, in Comparative Example 2, the montmorillonite modified by multiple chemical steps of the present invention was directly replaced with commercially available montmorillonite without any treatment. Although the modified dispersant was retained, the commercially available montmorillonite lacked reactive groups on its surface that could chemically bond with the modified dispersant or styrene monomer. As a result, it could only form weak physical adsorption with the polystyrene matrix, and the interfacial bonding was extremely poor. At the same time, the unmodified montmorillonite was highly hydrophilic and easily agglomerated in the aqueous suspension polymerization system, making it impossible to achieve uniform dispersion. The large particles formed by agglomeration became stress concentration points inside the material, which easily caused cracks and material failure under external force. Therefore, the tensile strength, flexural strength and compressive strength of this comparative example were significantly lower than those of the examples, and its impact resistance was also greatly reduced due to the lack of an effective energy dissipation mechanism.
[0054] From Table 1 and Figure 1As can be seen, compared with the examples, in Comparative Example 3, the dispersant modified by silane coupling agent of the present invention was replaced with commercially available hydroxyethyl cellulose without any chemical modification. Although modified montmorillonite was retained, commercially available hydroxyethyl cellulose can only play a conventional dispersing and stabilizing role. Its molecular chain lacks active groups that can undergo copolymerization reaction with the double bonds or polystyrene molecular chains on the surface of modified montmorillonite. It cannot be anchored in the material system through chemical bonds and is easily washed away in the subsequent washing process. More importantly, due to the lack of the bridging effect of the modified dispersant, although the modified montmorillonite itself is reactive, it cannot form a three-dimensional reinforcing network with the dispersant. The two exist independently in the material and it is difficult to play a synergistic effect. As a result, when the material is subjected to external force, the stress cannot be transmitted and dispersed through an effective network structure. Therefore, its tensile strength, flexural strength, impact strength and compressive strength are significantly worse than those of the examples.
[0055] From Table 1 and Figure 1 As can be seen, compared with the examples, in Comparative Example 4, the modified montmorillonite was replaced with commercially available montmorillonite, and the modified dispersant was replaced with commercially available hydroxyethyl cellulose. This scheme completely abandons the active reinforcement system constructed by the multi-step chemical modification of this invention. Commercially available montmorillonite not only has weak interfacial bonding with the polystyrene matrix and is prone to agglomeration, but also cannot participate in any chemical reaction; commercially available hydroxyethyl cellulose can only play a basic dispersing role, and cannot be anchored in the material through chemical bonds, nor can it form any form of synergistic reinforcement with montmorillonite. In this case, montmorillonite is randomly distributed in the material in the form of micron-sized agglomerates, which not only cannot play a reinforcing role, but also become a source of structural defects. The dispersant is lost in large quantities after washing, resulting in a lack of effective reinforcing phase and network structure inside the material. Therefore, the tensile strength, flexural strength, impact strength and compressive strength of the expandable polystyrene prepared in this comparative example are the lowest among all tested samples, which fully demonstrates that the technical solution of the present invention, which synergistically constructs a three-dimensional reinforcing network with modified montmorillonite and modified dispersant, plays an indispensable key role in comprehensively improving the mechanical properties of materials.
[0056] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.
Claims
1. An environmentally friendly, high-strength expandable polystyrene, characterized in that, The raw materials include the following parts by weight: 90-100 parts styrene monomer, 120-150 parts deionized water, 3-5 parts modified montmorillonite, 0.3-0.8 parts modified dispersant, 0.3-0.6 parts composite initiator, and 5-6 parts foaming agent; The preparation method of the modified montmorillonite is as follows: Step 1: Add sodium-based montmorillonite to deionized water at 55-65℃ and stir for 110-130 min. Let it stand and swell for 11.5-12.5 h. Then raise the temperature to 65-75℃, adjust the pH to 4.5-5.0, stir for 110-130 min, add aluminum sulfate aqueous solution, and continue stirring for 55-65 min. Then add citric acid and stir at 55-65℃ for 25-35 min. After post-treatment, activated montmorillonite is obtained. Step 2: Dissolve silane coupling agent KH-570 in anhydrous ethanol, add deionized water and glacial acetic acid, stir at room temperature for 25-35 min, then add activated montmorillonite, ultrasonically disperse for 25-35 min, heat to 70-75℃, stir and react under an inert atmosphere for 4-6 h, and obtain silane-modified montmorillonite after post-treatment. Step 3: Disperse the silane-modified montmorillonite in deionized water at 75-85℃ and ultrasonically disperse for 55-65 min. Then add hexadecyltrimethylammonium bromide and stir at 75-85℃ for 110-130 min. Then cool down to 65-75℃, add sodium dodecyl sulfonate and stir for 55-65 min. Finally, add polyethylene glycol and continue stirring for 55-65 min. After post-treatment, the modified montmorillonite is obtained.
2. The environmentally friendly high-strength expandable polystyrene according to claim 1, characterized in that, In step 1, the mass ratio of sodium montmorillonite, deionized water, aluminum sulfate aqueous solution, and citric acid is 100:1990-2010:25-50:2-3, and the mass fraction of aluminum sulfate aqueous solution is 1.8-2.2%.
3. The environmentally friendly high-strength expandable polystyrene according to claim 1, characterized in that, The mass ratio of silane coupling agent KH-570, anhydrous ethanol, deionized water, glacial acetic acid, and activated montmorillonite in step 2 is 10-12:470-480:20-30:2-3:
100.
4. The environmentally friendly high-strength expandable polystyrene according to claim 1, characterized in that, The mass ratio of silane-modified montmorillonite, deionized water, hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, and polyethylene glycol in step 3 is 100:1490-1510:35-40:3-5:4.5-5.
5.
5. The environmentally friendly high-strength expandable polystyrene according to claim 1, characterized in that, The modified dispersant is prepared as follows: hydroxyethyl cellulose is added to anhydrous ethanol and stirred at room temperature for 25-35 min. Then deionized water is added and stirred for another 55-65 min. The pH is then adjusted to 4.5-5.0, and silane coupling agent KH-570 is added. The mixture is stirred at room temperature for 35-45 min, then heated to 60-65℃ and stirred for 3-4 h. The modified dispersant is obtained after post-treatment.
6. The environmentally friendly high-strength expandable polystyrene according to claim 5, characterized in that, The mass ratio of the hydroxyethyl cellulose, anhydrous ethanol, deionized water, and silane coupling agent KH-570 is 100:490-510:25-35:8-10.
7. The environmentally friendly high-strength expandable polystyrene according to claim 1, characterized in that, The composite initiator is composed of benzoyl peroxide and tert-butyl peroxide in a mass ratio of 1:0.9-1.
1.
8. The environmentally friendly high-strength expandable polystyrene according to claim 1, characterized in that, The foaming agent is a mixture of n-pentane and isopentane in a mass ratio of 1:0.9-1.
1.
9. The method for preparing environmentally friendly high-strength expandable polystyrene according to any one of claims 1-8, characterized in that, Includes the following steps: Step (1): Add the modified dispersant to deionized water, stir to dissolve, then add the modified montmorillonite, and ultrasonically disperse for 25-35 minutes to obtain a suspension; Step (2): Mix the styrene monomer and the composite initiator, stir to dissolve, and then add to the suspension obtained in step (1). Heat to 80-85℃, stir and react for 4-6 hours, then heat to 90-95℃ and continue to react for 2-3 hours to obtain the polymer product. Step (3): Cool the polymerization product to 20-25℃, add foaming agent, stir for 30-60 minutes, then heat to 85-95℃ and maintain for 1-2 hours. After post-treatment, the product is obtained.