Preparation method of novel epoxy resin-based explosion-proof box

Abstract

The invention discloses a preparation method of a novel epoxy resin-based explosion-proof box. The preparation method comprises the following steps: (1) preparing a modified epoxy resin matrix; (2) preparing a toughening modifier: mixing 55-65 parts of polysulfone, 25-30 parts of polyethersulfone, 3-5 parts of nano graphene oxide and 2-3 parts of a compatilizer; (3) preparing a temperature response type nano particle compound: mixing 1 to 2 parts of hollow silicon dioxide nano particles, 0.5 to 1 part of PEG-PLA (Polyethylene Glycol-Polylactic Acid) copolymer and 0.3 to 0.6 part of nano TiO2; (4) mixing products obtained in the step (1) and the step (2) according to a weight ratio of 85: 15, and carrying out vacuum defoaming at 120-140 DEG C for 30 minutes; and (5) casting and molding the mixture, keeping at 150 DEG C for 2 hours, heating to 200 DEG C, keeping at 200 DEG C for 1 hour, and curing. The preparation method of the novel epoxy resin-based explosion-proof box has the following beneficial effects that the explosion-proof box prepared by the preparation method of the novel epoxy resin-based explosion-proof box has better mechanical property, heat resistance, corrosion resistance and flame retardance, and the performance of the explosion-proof box is gradually optimized along with the rise of the internal temperature in the use process.

Description

Technical Field

[0001] The present invention relates to a preparation method of a special explosion-proof box, and in particular to a preparation method of a new epoxy resin-based explosion-proof box. Background Art

[0002] As an important safety device for protecting electrical equipment in industrial production, the material properties of the explosion-proof box are directly related to the safety and reliability of the entire system. Traditional explosion-proof boxes are mainly made of metal materials such as aluminum alloy and stainless steel. Although these materials have certain strength and processing performance, more defects have gradually emerged in practical applications.

[0003] The existing explosion-proof box manufacturing process is usually as follows: First, the metal material is formed into a basic shell structure by casting or stamping; then, mechanical processing is carried out to make functional structures such as mounting holes and wiring ports; finally, surface treatment and anti-corrosion coating are carried out. Although this traditional process has relatively mature procedures, the product performance is difficult to meet the increasingly strict safety requirements.

[0004] In practical applications, there are obvious technical defects in the existing metal material explosion-proof boxes. One is the deficiency in mechanical properties. Especially when subjected to external impacts, the metal material is prone to deformation or cracking, which not only affects the sealing performance of the explosion-proof box but also may expose the internal electrical equipment to a dangerous environment. At the same time, the heat resistance of the metal material is poor, and it is prone to thermal deformation in a high-temperature environment, affecting the structural integrity of the explosion-proof box.

[0005] In special industrial environments such as chemical industry and petroleum, the explosion-proof box is often exposed to various corrosive gases or liquids. Even after anti-corrosion treatment, traditional metal materials are still difficult to resist long-term chemical erosion, resulting in the gradual degradation of material properties and shortening the product service life.

[0006] Although the metal material itself is non-combustible, it may soften or melt in a high-temperature environment and cannot effectively prevent the spread of flames. Especially when the internal electrical equipment of the explosion-proof box operates at a high temperature for a long time, it poses a greater potential safety hazard.

[0007] In addition, as the internal equipment of the explosion-proof box continues to operate, the internal temperature keeps rising, and the performance of the existing materials will further decline. Metal materials are prone to problems such as grain boundary weakening and fatigue cracking in a high-temperature environment, affecting the service life of the explosion-proof box.

[0008] Therefore, it is of great significance to prepare a new explosion-proof box material based on epoxy resin. Summary of the Invention

[0009] The purpose of the present invention is to provide a preparation method of a novel epoxy resin-based explosion-proof box. The explosion-proof box prepared by this preparation method of the novel epoxy resin-based explosion-proof box has good mechanical properties, heat resistance, corrosion resistance and flame retardancy, and enables the explosion-proof box to gradually optimize its performance as the internal temperature rises during use.

[0010] The above technical purpose of the present invention is achieved through the following technical solutions: A preparation method of a novel epoxy resin-based explosion-proof box includes the following steps: (1) Prepare a modified epoxy resin matrix: sequentially mix 70-80 parts of bisphenol A epoxy resin, 10-15 parts of epichlorohydrin, 3-5 parts of nano-aluminum oxide, 1-2 parts of organosilicon modifier, 20-25 parts of curing agent and 0.5-1 part of accelerator; (2) Prepare a toughening modifier: mix 55-65 parts of polysulfone, 25-30 parts of polyethersulfone, 3-5 parts of nano-graphene oxide and 2-3 parts of compatibilizer; (3) Prepare a temperature-responsive nanoparticle composite: mix 1-2 parts of hollow silica nanoparticles, 0.5-1 part of PEG-PLA copolymer and 0.3-0.6 part of nano-TiO2; (4) Mix the products of steps (1) and (2) according to a weight ratio of 85:15, and perform vacuum degassing at 120-140 °C for 30 minutes; (5) Cast and mold the mixture, keep it at 150 °C for 2 hours, and then raise the temperature to 200 °C and keep it for 1 hour for curing.

[0011] By adopting the above technical solutions and through the above process steps, the mechanical properties, thermal stability, flame retardancy and chemical corrosion resistance of the explosion-proof box are significantly improved. The three-dimensional cross-linked network structure of epoxy resin enhances the strength and toughness of the material; the addition of nano-aluminum oxide effectively improves the tensile strength and impact strength, and at the same time enhances the heat resistance and dimensional stability; the organosilicon modifier improves the interfacial bonding force between the filler and the matrix. The toughening effect of polysulfone and polyethersulfone significantly improves the impact resistance and fracture toughness of the material; the two-dimensional sheet structure of nano-graphene oxide effectively prevents crack propagation and improves the interfacial strength. The hollow silica particles provide heat insulation and dimensional stability; the PEG-PLA copolymer decomposes under high-temperature conditions, exposing active hydroxyl groups, forming additional cross-linking points with the matrix, and realizing high-temperature performance optimization; the catalytic effect of nano-TiO2 accelerates the interfacial reaction and further improves the comprehensive performance of the material.

[0012] The present invention is further configured as: step (1) includes: heating bisphenol A epoxy resin to 80 °C and then adding epichlorohydrin; dispersing nano-aluminum oxide at a high speed of 8000-12000 rpm for 30 minutes; continuing to stir for 15 minutes after adding the organosilicon modifier; adding the curing agent and accelerator when the temperature drops below 60 °C, and stirring at a low speed.

[0013] By adopting the above technical solution, 70 - 80 parts of epoxy resin, 10 - 15 parts of epichlorohydrin, 3 - 5 parts of nano-aluminum oxide, 1 - 2 parts of organosilicon modifier, 20 - 25 parts of curing agent and 0.5 - 1 part of accelerator are mixed in sequence to ensure the uniformity and interfacial bonding strength of the material. The introduction of epichlorohydrin improves the fluidity of the epoxy resin and optimizes the processing performance; the nano-aluminum oxide is dispersed by high-speed stirring and evenly distributed in the matrix, enhancing the impact resistance and tensile strength of the material, and at the same time improving the heat resistance; the organosilicon modifier enhances the interfacial bonding strength between the filler and the matrix through chemical bonding, improving the dimensional stability and crack resistance of the material; the addition of the curing agent and accelerator ensures the complete cross-linking of the epoxy resin, enhancing the mechanical properties and chemical corrosion resistance of the material.

[0014] The present invention is further configured as follows: The step (2) includes: dissolving polysulfone and polyethersulfone in dimethylacetamide or dimethyl sulfoxide, heating to 120 °C; ultrasonically dispersing nano-graphene oxide for 30 minutes; adding maleic anhydride-modified polymer as a compatibilizer and stirring for 30 minutes.

[0015] By adopting the above technical solution, through the cooperative design of polysulfone (55 - 65 parts), polyethersulfone (25 - 30 parts), nano-graphene oxide (3 - 5 parts) and compatibilizer (2 - 3 parts), the toughness and crack resistance of the material are significantly enhanced. The flexible molecular chain segments of polysulfone and polyethersulfone absorb external impact energy through physical entanglement, significantly improving the impact resistance of the material; the two-dimensional structure of nano-graphene oxide effectively hinders the crack propagation path and enhances the crack resistance of the material through crack deflection and bridging; the compatibilizer (such as maleic anhydride-modified polymer) improves the compatibility of polysulfone, polyethersulfone and epoxy resin matrix, enhancing the interfacial bonding strength.

[0016] The present invention is further configured as follows: The step (3) includes: reacting hollow silica nanoparticles with PEG-PLA copolymer at 60 °C for 3 hours for surface modification; ball-milling the modified hollow silica with nano-TiO2 for 2 hours.

[0017] By adopting the above technical solution, a nanoparticle composite with optimized dynamic performance is prepared by mixing and processing 1-2 parts of hollow silica particles, 0.5-1 part of PEG-PLA copolymer, and 0.3-0.6 part of nano-TiO2. The hollow silica particles form a heat insulation barrier at high temperatures, reducing heat transfer. At the same time, their hollow structure reduces the coefficient of thermal expansion, improving the dimensional stability of the material. The PEG-PLA copolymer gradually decomposes in the range of 120-180 °C, exposing reactive hydroxyl groups, which chemically react with the epoxy matrix to form a new cross-linked network, further enhancing the mechanical properties and thermal stability in high-temperature environments. Nano-TiO2 catalyzes the chemical reaction of hydroxyl groups on the surface of SiO2 particles in high-temperature environments, accelerating interfacial bonding and optimizing the material properties.

[0018] The present invention is further configured such that: the nano-aluminum oxide is pre-dispersed with ethanol before being added.

[0019] By adopting the above technical solution, pre-dispersing the nano-aluminum oxide with ethanol improves the dispersibility of the particles and avoids agglomeration. The uniform distribution of nano-aluminum oxide in the matrix significantly enhances the tensile strength and impact resistance of the material. Through pre-dispersion treatment, the interfacial bonding force between nano-aluminum oxide and the epoxy resin matrix is enhanced, further improving the dimensional stability and heat resistance of the material.

[0020] In summary, the present invention has the following beneficial effects: Through the curing cross-linking reaction of the epoxy resin matrix, the epoxy groups (-CH2-O-CH-) react with the active groups (amine groups, carboxyl groups, etc.) in the curing agent to form a three-dimensional cross-linked network. The specific reaction is as follows: The epoxy groups react with amine curing agents to generate hydroxyl groups (-OH) and C-N bonds, forming a preliminary cross-linking: -CH2-O-CH-+R-NH2→-CH2-OH+-CH-NH-R This reaction proceeds fully during the process of maintaining at 150 °C for 2 hours to form a stable three-dimensional cross-linked network.

[0021] Further condensation reaction of hydroxyl groups: Under high-temperature conditions (maintaining at 200 °C for 1 hour), the hydroxyl groups (-OH) in the system can undergo a condensation reaction with the reactive hydroxyl groups on the surface of nano-fillers (such as SiO2) to generate stronger Si-O-C bonds: -Si-OH+-CH2-OH→-Si-O-CH2-+H2O Through the above cross-linking reactions, the interfacial bonding force between the matrix and the filler is significantly improved, enhancing the mechanical properties and thermal stability of the overall explosion-proof box material.

[0022] After the surface hydroxyl groups (-OH) of nano-aluminum oxide (Al2O3) particles are treated with an organosilicon modifier (such as a silane coupling agent), chemical bonds can be formed with the epoxy resin matrix: The siloxane group (Si-O-Si) of the silane coupling agent can react with the hydroxyl groups on the surface of Al2O3 to form chemical bonds; The organic groups (epoxy groups or amino groups) at the other end of the coupling agent can chemically combine with the matrix of the epoxy resin to enhance the interfacial bonding strength.

[0023] Through the above chemical reactions, the nano-aluminum oxide is evenly dispersed and can also hinder the crack propagation path, thereby improving the impact resistance and crack resistance of the material.

[0024] Polysulfone and polyethersulfone are high-performance thermoplastic polymers. Their molecular chains contain aromatic rings and ether bonds, and they have good flexibility and heat resistance; In the epoxy resin matrix, polysulfone and polyethersulfone are distributed in the crosslinked network in a physically entangled manner, which can absorb external impact energy and significantly improve the impact resistance and fracture toughness of the material; at the same time, the active groups (hydroxyl groups, carboxyl groups, etc.) in the toughening modifier can form hydrogen bonds or covalent bonds with the epoxy resin matrix to further improve the interfacial bonding force.

[0025] Nano-graphene oxide (GO) is a two-dimensional layered material. Its surface contains oxygen-containing functional groups (such as carboxyl groups, hydroxyl groups, epoxy groups, etc.), and these groups can undergo chemical reactions with the epoxy resin matrix: Ring-opening reaction of carboxyl group (-COOH) with epoxy group: -CH2-O-CH-+HOOC-→-CH2-OH+O=C-O The hydrogen bond interaction between the hydroxyl group (-OH) and the matrix improves the bonding strength of the interface; The two-dimensional sheet structure of nano-graphene oxide (GO) blocks the crack propagation path and provides crack deflection and crack bridging enhancement.

[0026] The hollow structure of hollow silica particles (h-SiO2) can effectively reduce the thermal expansion coefficient of the material and improve the dimensional stability of the material in a high-temperature environment; Thermal insulation barrier: The hollow structure forms a thermal insulation effect at high temperatures, delays heat transfer, and improves the heat resistance of the material.

[0027] The surface of h-SiO2 contains a large number of hydroxyl groups (-OH), which can undergo chemical reactions with the hydroxyl groups in the epoxy resin matrix at high temperatures to further enhance the interfacial bonding force.

[0028] In the prior art, the surface energy of h-SiO2 particles is high, and they are prone to agglomeration. The interfacial bonding force between h-SiO2 particles and the matrix is weak, which may form stress concentration points and reduce the mechanical properties of the system (such as crack concentration). In the present invention, a modified layer is formed on the surface of the nanoparticles by the PEG-PLA copolymer, which reduces the surface energy of the h-SiO2 particles, reduces the agglomeration situation, and prevents it from affecting the mechanical properties of the system.

[0029] The decomposition temperature of the PEG-PLA copolymer is usually between 120-180 °C: during the high-temperature operation of the explosion-proof box (above 120 °C), the PEG-PLA modifier gradually decomposes, exposing the active hydroxyl groups (-OH) on the surface of SiO2; the hydroxyl groups react chemically with the residual active groups (hydroxyl or epoxy groups) in the epoxy resin matrix to generate new cross-linking points, further improving the mechanical properties and thermal stability of the material.

[0030] Nano-TiO2 has catalytic activity in a high-temperature (above 120 °C) environment, which can accelerate the activation reaction of surface hydroxyl groups of SiO2: -CH2-OH + HO-Si → -CH2-O-Si- + H2O, not only improving the interfacial reaction rate, but also significantly enhancing the dynamic performance optimization of the material in a high-temperature environment, and solving the problem of performance degradation caused by high-temperature degradation of traditional materials.

[0031] During the operation of the explosion-proof box, high-temperature conditions (120-200 °C) stimulate the dynamic reaction of temperature-responsive nanoparticles: After the PEG-PLA modifier decomposes, the hydroxyl groups on the surface of SiO2 are exposed and chemically react with the matrix to form a denser interfacial bond; Nano-graphene oxide prevents crack propagation through its lamellar structure and forms additional chemical cross-linking points with the matrix at high temperatures. This dynamic cross-linking gradually optimizes the mechanical properties of the material in a high-temperature environment, while repairing micro-cracks and extending the service life of the material.

[0032] The microscopic void structure of hollow silica can effectively absorb thermal expansion strain and reduce the thermal expansion coefficient of the material; at the same time, the thermal insulation barrier provided by the hollow particles reduces heat transfer, thereby further improving the stability of the material in a high-temperature environment.

[0033] This dynamic performance optimization enables the explosion-proof box not only to avoid material deterioration under high-temperature operating conditions, but also to gradually improve the material properties of the explosion-proof box.

[0034] In the extreme case of internal combustion in the explosion-proof box, the present invention will produce additional effects: Hollow silica particles do not decompose directly in a high-temperature combustion environment and contain a small amount of adsorbed air or moisture. When the temperature rises, they are released as water vapor or trace nitrogen; the water vapor can dilute the oxygen concentration generated during combustion, thereby inhibiting flame propagation.

[0035] In addition, PEG-PLA gradually decomposes in the range of 120 - 180 °C, and its decomposition products are mainly carbon dioxide (CO2), water (H2O) and a small amount of inert gas (nitrogen); These gases can dilute the oxygen concentration in a high-temperature combustion environment and form an inert gas barrier in the combustion area, reducing the combustion rate.

[0036] In summary, the preparation method of this new type of epoxy resin-based explosion-proof box realizes the improvement of material properties and intelligent response through multi-component composite design. Bisphenol A epoxy resin and epichlorohydrin form a basic network structure, and the interfacial bonding force is enhanced by nano-alumina and silicone modifiers; the toughening modification of polysulfone and polyethersulfone in combination with the lamellar structure of nano-graphene oxide significantly improves the impact resistance and fracture toughness of the material. Especially the temperature-responsive nanoparticle system. Under the surface modification of hollow silica nanoparticles by PEG-PLA copolymer and the catalytic action of nano-TiO2, the interfacial reaction can be gradually activated as the internal temperature of the explosion-proof box rises (120 - 200 °C), not only repairing microcracks but also continuously optimizing the material properties. At the same time, the composite material will release water vapor and inert gas under extreme combustion conditions, forming a flame retardant barrier. This dynamic response mechanism enables the performance of the explosion-proof box to increase rather than decrease during high-temperature operation, improving the service life and safety performance of the product. Specific implementation mode

[0037] A preparation method of a new type of epoxy resin-based explosion-proof box includes the following steps: (1) Prepare a modified epoxy resin matrix: Heat 70 - 80 parts of bisphenol A epoxy resin to 80 °C and then add 10 - 15 parts of epichlorohydrin; perform pre-dispersion treatment with ethanol and stir and disperse 3 - 5 parts of nano-alumina at a high speed of 8000 - 12000 rpm for 30 minutes; add 1 - 2 parts of silicone modifier and continue stirring for 15 minutes; add 20 - 25 parts of curing agent and 0.5 - 1 part of accelerator when the temperature drops below 60 °C, and stir at a low speed.

[0038] (2) Prepare a toughening modifier: Dissolve 55 - 65 parts of polysulfone and 25 - 30 parts of polyethersulfone in dimethylacetamide or dimethyl sulfoxide and heat to 120 °C; ultrasonically disperse 3 - 5 parts of nano-graphene oxide for 30 minutes; add 2 - 3 parts of maleic anhydride-modified polymer as a compatibilizer and stir for 30 minutes (3) Preparation of temperature-responsive nanoparticle composites: 1-2 parts of hollow silica nanoparticles are reacted with 0.5-1 part of PEG-PLA copolymer at 60 °C for 3 hours for surface modification; the modified hollow silica is ball-milled with 0.3-0.6 part of nano-TiO₂ for 2 hours.

[0039] (4) Mix the products of steps (1) and (2) in a weight ratio of 85:15, and degas under vacuum at 120-140 °C for 30 minutes; (5) Cast and mold the mixture, keep it at 150 °C for 2 hours, and then raise the temperature to 200 °C and keep it for 1 hour for curing.

[0040] According to the above preparation method, the present invention designed the following experiments: By setting up 5 experimental groups and 2 control groups, the performance improvement effect of the epoxy resin-based explosion-proof box is comprehensively verified. The experimental groups and the control groups adjust the ratio of key components (such as polysulfone, polyethersulfone, nano-graphene oxide, hollow silica, PEG-PLA copolymer, and nano-TiO₂, etc.) through the system.

[0041] 1. Setting of experimental groups and control groups: As shown in Table 1: Table 1: Design of experimental groups and control groups Group Polysulfone (parts) Polyethersulfone (parts) Nanographene oxide (parts) Hollow silica (parts) PEG-PLA copolymer (parts) <![CDATA[Nanometer TiO2 (parts)]]> Remarks Experimental group 1 60 28 4.5 1.5 0.8 0.5 Complete formulation (each experimental group and control group used 70 parts of bisphenol A epoxy resin, 12 parts of epichlorohydrin, and 4 parts of nanoaluminum oxide). Experimental group 2 60 28 4.5 1.5 - 0.5 PEG-PLA copolymer removed, lacking dynamic performance optimization function. Experimental group 3 60 28 - 1.5 0.8 0.5 Nanographene oxide removed, lacking crack propagation resistance. Experimental group 4 60 - 4.5 1.5 0.8 0.5 Polyethersulfone removed, reducing flexibility and impact resistance. Experimental group 5 - 28 4.5 1.5 0.8 0.5 Polysulfone removed, reducing toughening ability. Control group 1 - - - - - - Without reinforcing components, only a basic epoxy resin system. Control group 2 60 28 4.5 - - - Only contains toughening agents (polysulfone / polyethersulfone), without nano-reinforcing components.

[0042] 2. Experimental design and test plan Experimental objectives: Verify the following properties through experiments: Mechanical properties (tensile strength, impact strength, compressive strength): Evaluate the improvement effect of components on the strength and toughness of materials.

[0043] Heat resistance properties (thermal decomposition temperature, coefficient of thermal expansion): Test the stability and dimensional retention ability under high-temperature conditions.

[0044] Corrosion resistance properties (corrosion rate, mass loss rate): Verify the performance of materials in acid-base corrosion environments.

[0045] Flame retardant properties (oxygen index, UL-94 rating): Test the flame retardant properties of materials.

[0046] Dynamic performance optimization (dynamic changes in mechanical properties at high temperatures): Verify the dynamic optimization effect of PEG-PLA and temperature-responsive nanoparticles.

[0047] Experiment 1: Mechanical property test Experimental purpose: Test the effects of different components on tensile strength, impact strength, and compressive strength.

[0048] Experimental procedures: Prepare samples for each experimental group and the control group, with specimens sized 100 mm × 10 mm × 4 mm. Test the tensile strength, impact strength, and compressive strength at normal temperature (25°C) and high temperature (150°C) respectively. Conduct each test 3 times for each group and take the average value.

[0049] Test standards: Tensile strength: GB / T1040.2 - 2006; Impact strength: GB / T2571 - 1995; Compressive strength: GB / T1041 - 2008 Test equipment: Tensile testing machine (accuracy 0.01 MPa); Impact testing machine; Compression testing machine. The experimental results are shown in Table 2: Table 2: Mechanical property tests Group Temperature (°C) Tensile strength (MPa) Impact strength (kJ / m²) Compressive strength (MPa) Remarks Experimental group 1 25 85.5 12.8 155.2 Complete formulation, excellent performance. 150 90.2 13.5 160.3 Significant dynamic optimization effect at high temperatures. Experimental group 2 25 78.4 11.2 145.3 Without PEG-PLA, lacking dynamic optimization ability. 150 78.8 11.5 146.0 Limited improvement in high-temperature performance. Experimental group 3 25 76.2 10.9 143.8 Without nanographene oxide, crack resistance decreased. 150 76.5 11.0 144.0 Limited improvement in performance at high temperatures. Experimental group 4 25 74.3 10.5 140.2 Without polyethersulfone, impact resistance decreased significantly. 150 74.8 10.7 141.0 High-temperature performance remained basically stable. Experimental group 5 25 73.5 10.2 138.9 Without polysulfone, toughening ability insufficient. 150 74.0 10.3 139.5 Little change in high-temperature performance. Control group 1 25 65.2 8.8 130.5 Without any reinforcing components, lowest performance. 150 65.5 8.9 131.0 No significant improvement in high-temperature performance. Control group 2 25 72.4 9.5 135.6 Without nano-reinforcing components, only relying on toughening agents to improve performance. 150 73.0 9.7 136.2 Performance slightly improved, but dynamic optimization effect insufficient. Experiment 2: Heat resistance performance test Experiment purpose: Test the effects of different components on the thermal decomposition temperature and coefficient of thermal expansion.

[0050] Experimental procedures: Prepare samples for each experimental group and the control group, with specimens sized as circular wafers (diameter 10 mm, thickness 2 mm). Use a thermogravimetric analyzer (TGA) to test the thermal decomposition temperature of the samples (temperature range: room temperature to 800°C). Use a thermomechanical analyzer (TMA) to test the coefficient of thermal expansion of the samples.

[0051] Test standards: Thermal decomposition temperature: GB / T2951.13 - 2008; Coefficient of thermal expansion: GB / T2577 - 1989.

[0052] Test equipment: Thermogravimetric analyzer (TGA); Thermomechanical analyzer (TMA). The experimental results are shown in Table 3: Table 3: Heat resistance performance tests Group Thermal decomposition temperature (°C) <![CDATA[Coefficient of thermal expansion (10 -6 / °C)]]> Remarks Experimental group 1 320 45 Complete formulation, excellent heat resistance. Experimental group 2 300 50 Without PEG-PLA, slightly lower dynamic performance optimization. Experimental group 3 310 48 Without nanographene oxide, slightly lower thermal stability. Experimental group 4 305 52 Without polyethersulfone, dimensional stability decreased. Experimental group 5 307 51 Without polysulfone, slightly lower heat resistance. Control group 1 280 65 Without any reinforcing components, significant decrease in heat resistance. Control group 2 290 60 Without nano-reinforcing components, poor heat resistance. Experiment 3: Corrosion resistance performance test Experiment purpose: Verify the effects of different components on the acid and alkali corrosion resistance of the material.

[0053] Experimental procedures: Immerse the samples in 10% hydrochloric acid, 10% sulfuric acid, and 10% sodium hydroxide solutions respectively for 7 days. Measure the corrosion rate and mass loss rate.

[0054] Test standards: Corrosion rate: GB / T3836.1 - 2010; Mass loss rate: GB / T16545 - 1996 Test equipment: Electronic balance (accuracy 0.001 g); Constant temperature water bath.

[0055] Table 4: Corrosion resistance tests Group Solution type Corrosion rate (mm / year) Mass loss rate (%) Remarks Experimental group 1 Hydrochloric acid 0.02 0.3 Excellent corrosion resistance. Sulfuric acid 0.03 0.4 Sodium hydroxide 0.01 0.2 Experimental group 2 Hydrochloric acid 0.05 0.6 Without PEG-PLA, slightly lower corrosion resistance. Sulfuric acid 0.06 0.7 Sodium hydroxide 0.03 0.4 Experimental group 3 Hydrochloric acid 0.04 0.5 Without nanographene oxide, stronger corrosion propagation ability. Sulfuric acid 0.05 0.6 Sodium hydroxide 0.02 0.3 Experimental group 4 Hydrochloric acid 0.06 0.7 Without polyethersulfone, further decrease in corrosion resistance. Sulfuric acid 0.07 0.8 Sodium hydroxide 0.04 0.5 Experimental group 5 Hydrochloric acid 0.07 0.8 Without polysulfone, poor corrosion resistance. Sulfuric acid 0.08 0.9 Sodium hydroxide 0.05 0.6 Control group 1 Hydrochloric acid 0.10 1.0 Without any reinforcing components, worst corrosion performance. Sulfuric acid 0.12 1.2 Sodium hydroxide 0.08 0.9 Control group 2 Hydrochloric acid 0.08 0.9 Without nano-reinforcing components, poor corrosion resistance. Sulfuric acid 0.09 1.0 Sodium hydroxide 0.06 0.7 Experiment 4: Flame retardant performance test Purpose of the experiment: To evaluate the effects of different components on the flame retardancy performance (oxygen index and UL-94 flame retardancy rating) of the material.

[0056] Experimental procedures: Oxygen index test: Sample preparation: Prepare specimens with dimensions of 100 mm × 10 mm × 4 mm according to the standard. Use an oxygen index tester to measure the lowest oxygen concentration for combustion (LOI) of the sample in a mixed gas of oxygen and nitrogen.

[0057] UL-94 flame retardancy test: Sample preparation: Prepare specimens according to the UL-94 standard. Test the horizontal and vertical combustion performances and evaluate the flame retardancy rating (V-0, V-1, V-2).

[0058] Test standards: Oxygen index: GB / T2406-2008; UL-94 flame retardancy test: UL-94.

[0059] Test equipment: Oxygen index tester; UL-94 horizontal / vertical combustion test device.

[0060] The experimental results are shown in Table 5: Table 5: Flame retardancy performance test Group Oxygen index (%) UL-94 rating Remarks Experimental group 1 35 V-0 Complete formulation, high oxygen index, excellent flame retardancy. Experimental group 2 32 V-1 Without PEG-PLA, lack of dynamic flame retardant effect of copolymer decomposition. Experimental group 3 33 V-1 Without nanographene oxide, slightly lower flame retardancy. Experimental group 4 31 V-2 Without polyethersulfone, significant decrease in flame retardancy. Experimental group 5 30 V-2 Without polysulfone, poor flame retardancy. Control group 1 28 Unqualified Without reinforcing components, lowest flame retardancy. Control group 2 30 V-2 Without nano-reinforcing components, weak flame retardancy. Experiment 5: Dynamic performance optimization test Purpose of the experiment: To verify the dynamic performance optimization effect of the nanoparticle composite (hollow silica, PEG-PLA copolymer, nano-TiO2) under high-temperature conditions and test the dynamic improvement effect of the mechanical properties of the explosion-proof box material with temperature change.

[0061] Experimental procedures: Sample preparation: Prepare specimens with dimensions of 100 mm × 10 mm × 4 mm. High-temperature environment test: Place the samples successively into a high-temperature oven. After isothermal holding at 120 °C, 150 °C, 180 °C, and 200 °C for 30 minutes, test the tensile strength and impact strength respectively and record the performance changes. Evaluation of dynamic performance changes: Compare the performances of each group at different temperatures and analyze the dynamic optimization effect.

[0062] Test standards: Tensile strength: GB / T1040.2-2006; Impact strength: GB / T2571-1995.

[0063] Test equipment: High-temperature oven (temperature range: room temperature to 300 °C); Tensile testing machine (accuracy 0.01 MPa); Impact testing machine.

[0064] The experimental results are shown in Table 6: Table 6: Dynamic performance optimization test Group Temperature (°C) Tensile strength (MPa) Impact strength (kJ / m²) Remarks Experimental group 1 120 87.8 13.1 Dynamic optimization takes effect and the performance is significantly improved. 150 90.2 13.5 The dynamic performance is further optimized at high temperature. 180 92.5 14.0 The performance reaches the peak and the dynamic optimization fully plays its role. 200 93.0 14.2 Microcracks are repaired and the performance is stable. Experimental group 2 120 78.5 11.5 Without PEG-PLA, the dynamic optimization ability is insufficient. 150 79.2 11.6 The performance improvement is limited and no dynamic optimization trend is shown. 180 80.0 11.8 The performance is slightly improved. 200 80.2 11.9 The high-temperature performance is basically stable. Experimental group 3 120 79.0 11.8 Without nano-graphene oxide, the crack propagation ability is enhanced. 150 79.8 12.0 The performance improvement amplitude is limited. 180 80.5 12.1 The dynamic optimization performance is insufficient. 200 80.8 12.2 The performance improvement amplitude is small. Experimental group 4 120 75.0 10.8 Without polyethersulfone, the impact resistance drops significantly. 150 75.5 11.0 The performance improvement is not significant. 180 76.0 11.2 The high-temperature performance is basically stable. 200 76.3 11.3 There is no dynamic optimization effect. Experimental group 5 120 74.5 10.5 Without polysulfone, the toughening ability is insufficient. 150 75.0 10.7 The performance is slightly improved. 180 75.3 10.9 The dynamic optimization performance is insufficient. 200 75.5 11.0 The high-temperature performance improvement is limited. Control group 1 120 65.0 9.5 Without any reinforcing components, the performance is the lowest. 150 65.2 9.6 The performance basically remains unchanged at high temperature. 180 65.4 9.7 The performance remains stable, but there is no dynamic optimization effect. 200 65.5 9.8 The high-temperature performance has no improvement. Control group 2 120 72.0 10.2 Without nano-reinforcing components, the performance is relatively low. 150 72.5 10.4 The performance is slightly improved, but there is no significant dynamic optimization trend. 180 73.0 10.6 The performance remains stable. 200 73.2 10.7 The high-temperature performance improvement is limited. Conclusion: 1. Mechanical properties: The comprehensive mechanical properties of Experimental Group 1 are the best. Its tensile strength, impact strength, and compressive strength are better than those of other groups at both room temperature and high temperature. Especially at high temperature (150 °C), it shows a significant dynamic optimization effect, verifying the synergistic toughening effect of PEG-PLA copolymer, nano-graphene oxide, polysulfone, and polyethersulfone. In Experimental Group 2, the PEG-PLA copolymer is missing, and the dynamic optimization ability decreases significantly, indicating that the PEG-PLA copolymer generates crosslinking points by exposing hydroxyl groups at high temperature, significantly improving the mechanical properties. In Experimental Group 3, nano-graphene oxide is missing, the crack propagation ability is enhanced, and the impact resistance decreases, indicating that the two-dimensional sheet structure of nano-graphene oxide is important for inhibiting crack propagation. Removing polyethersulfone and polysulfone from Experimental Group 4 and Experimental Group 5 respectively results in insufficient toughening performance and decreased impact resistance. The performance of Control Group 1 is the lowest, indicating that the basic epoxy resin system cannot meet the requirements of high-performance explosion-proof boxes.

[0065] 2. Heat resistance The thermal decomposition temperature of Experimental Group 1 reaches 320 °C, and the thermal expansion coefficient is the lowest (45×10 -6 / °C), verifying the role of hollow silica, PEG-PLA copolymer, and nano-TiO2 in improving heat resistance. The heat resistance of Experimental Group 2 and Experimental Group 3 is slightly lower, indicating that the PEG-PLA copolymer and nano-graphene oxide have a positive effect on thermal stability at high temperature. The thermal expansion coefficients of Experimental Group 4 and Experimental Group 5 are higher, indicating that polysulfone and polyethersulfone play a greater role in ensuring dimensional stability at high temperature. The heat resistance of Control Group 1 deteriorates significantly, verifying the necessity of reinforcing components for improving heat resistance.

[0066] 3. Corrosion resistance The corrosion rate and mass loss rate of Experimental Group 1 are the lowest in hydrochloric acid, sulfuric acid, and sodium hydroxide environments, verifying the multiple enhancement effects of nano-graphene oxide, PEG-PLA copolymer, and hollow silica on anti-corrosion performance. The corrosion performance of Experimental Group 2 and Experimental Group 3 decreases, indicating that the dynamic crosslinking effect of the PEG-PLA copolymer and the crack inhibition ability of nano-graphene oxide are important for improving corrosion resistance. The corrosion performance of Experimental Group 4 and Experimental Group 5 further decreases, reflecting the importance of polysulfone and polyethersulfone in preventing the penetration of corrosive media. The corrosion rate of Control Group 1 is the highest, indicating the insufficient performance of the basic epoxy resin system in a chemical corrosion environment.

[0067] 4. Flame retardancy The oxygen index of Experimental Group 1 reached 35%, and the UL-94 rating was V-0, verifying the synergistic flame retardant effect of hollow silica, PEG-PLA copolymer, and nano-TiO2. The absence of PEG-PLA copolymer (Experimental Group 2) or nano-graphene oxide (Experimental Group 3) led to a decrease in the oxygen index to 32% and 33%, and the flame retardant rating dropped to V-1, indicating that dynamic response and crack inhibition are important in flame retardant performance. The oxygen indices of Experimental Groups 4 and 5 were further reduced to 31% and 30%, and the flame retardant rating dropped to V-2, indicating that toughening agents (polysulfone and polyethersulfone) play a certain role in flame retardant performance. Control Group 1 had the worst flame retardancy, with an oxygen index of only 28% and was unable to pass the UL-94 test, verifying the core role of the reinforcing component in improving flame retardant performance.

[0068] 5. Dynamic Performance Optimization The tensile strength of Experimental Group 1 at high temperature (200 °C) reached 93.0 MPa, and the impact strength reached 14.2 kJ / m², showing a significant dynamic performance optimization effect. It was verified that the PEG-PLA copolymer exposes hydroxyl groups through decomposition at high temperature and forms new crosslinking points with the epoxy matrix, thereby repairing microcracks and improving performance. The performance improvement of Experimental Groups 2 and 3 at high temperature was limited, indicating the core role of PEG-PLA copolymer and nano-graphene oxide in dynamic optimization. The performance improvement of Experimental Groups 4 and 5 was even smaller, indicating that polysulfone and polyethersulfone play a certain role in dynamic performance optimization. The high-temperature performance of Control Group 1 did not change significantly, verifying that the basic epoxy resin system cannot achieve dynamic performance optimization at high temperature.

[0069] Based on the above experimental results, the following conclusions were obtained: Significant improvement in mechanical properties: The complete formulation increased the tensile strength to 93.0 MPa and the impact strength to 14.2 kJ / m², showing excellent high strength and high toughness.

[0070] Excellent heat resistance: The thermal decomposition temperature reached 320 °C, and the coefficient of thermal expansion decreased significantly, meeting the requirements for high-temperature use.

[0071] Enhanced corrosion resistance: Low corrosion rate and mass loss rate, suitable for various corrosive environments.

[0072] Superior flame retardant performance: The oxygen index is as high as 35%, and the UL-94 rating is V-0, with excellent flame retardant performance.

[0073] Dynamic performance optimization: The performance increases instead of decreasing under high-temperature conditions, extending the service life of the material and meeting the requirements of extreme environments.

[0074] This specific embodiment is only an interpretation of the present invention and is not a limitation thereof. After reading this specification, those skilled in the art may make modifications to this embodiment that do not contribute creatively as needed, but as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A preparation method of a novel epoxy resin-based explosion-proof box, characterized in that, It includes the following steps: (1) Prepare a modified epoxy resin matrix: Mix 70 - 80 parts of bisphenol A epoxy resin, 10 - 15 parts of epichlorohydrin, 3 - 5 parts of nano-aluminum oxide, 1 - 2 parts of organosilicon modifier, 20 - 25 parts of curing agent, and 0.5 - 1 part of accelerator in sequence; (2) Prepare a toughening modifier: Mix 55 - 65 parts of polysulfone, 25 - 30 parts of polyethersulfone, 3 - 5 parts of nano-graphene oxide, and 2 - 3 parts of compatibilizer; (3) Prepare a temperature-responsive nanoparticle composite: Mix 1 - 2 parts of hollow silica nanoparticles, 0.5 - 1 part of PEG-PLA copolymer, and 0.3 - 0.6 part of nano-TiO₂; (4) Mix the products of steps (1) and (2) in a weight ratio of 85:15, and perform vacuum degassing at 120 - 140 °C for 30 minutes; (5) Cast and mold the mixture, cure it at 150 °C for 2 hours, and then raise the temperature to 200 °C and hold for 1 hour.

2. The preparation method according to claim 1, characterized in that, The step (1) includes: Heat the bisphenol A epoxy resin to 80 °C and then add epichlorohydrin; Stir and disperse the nano-aluminum oxide at a high speed of 8000 - 12000 rpm for 30 minutes; Continue stirring for 15 minutes after adding the organosilicon modifier; Add the curing agent and accelerator when the temperature drops below 60 °C and stir at a low speed.

3. The preparation method according to claim 1, wherein The step (2) includes: Dissolve the polysulfone and polyethersulfone in dimethylacetamide or dimethyl sulfoxide and heat to 120 °C; Ultrasonically disperse the nano-graphene oxide for 30 minutes; Add maleic anhydride-modified polymer as a compatibilizer and stir for 30 minutes.

4. The preparation method according to claim 1, wherein The step (3) includes: React the hollow silica nanoparticles with the PEG-PLA copolymer at 60 °C for 3 hours for surface modification; Ball-mill the modified hollow silica and nano-TiO₂ for 2 hours.

5. The preparation method according to claim 1, characterized in that, The nano-aluminum oxide is pre-dispersed with ethanol before addition.

6. An explosion-proof box, characterized in that, Prepared by the method according to any one of claims 1 - 5.