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In high-tech fields such as aerospace, energy extraction, automotive manufacturing, and industrial equipment, rubber products often need to withstand extreme high temperatures, pressures, or strong corrosive environments. Traditional rubber materials are prone to thermal aging, mechanical performance degradation, and even decomposition at high temperatures, leading to sealing failure, structural damage, and other issues. High temperature resistant rubber compounds can significantly improve the reliability of rubber products under extreme working conditions through molecular structure design, filler optimization, and process innovation. This article will analyze how high-temperature resistant rubber products can cope with challenges of high temperature, high pressure, and complex chemical environments from four aspects: material selection, formula design, process optimization, and application cases.

 

1、 Material Selection: Breakthrough from Molecular Structure to Thermal Stability

1. Silicone rubber: the "elastic guardian" at high temperatures

Silicone rubber (such as methyl vinyl silicone rubber VMQ) has become a material for high-temperature resistant rubber due to its unique silicon oxygen bond (Si-O) structure. The bond energy of silicon oxygen bond (422.5 kJ/mol) is much higher than that of carbon carbon bond (347 kJ/mol), allowing it to maintain elasticity above 250 ℃. For example, in aviation engine seals, VMQ rubber can work continuously for 5000 hours at 200 ℃ with a compression deformation rate of less than 15%, far superior to nitrile rubber (NBR) which has a compression deformation rate of over 30%. In addition, the low-temperature performance of silicone rubber (maintaining flexibility at -60 ℃) makes it an ideal material for components such as oil seals and O-rings in the aerospace industry.

 

2. Fluororubber: a "chemical shield" in highly corrosive environments

Fluororubber (such as FKM, FFKM) endows materials with extremely strong chemical and high temperature resistance by introducing fluorine atoms. Perfluoroether rubber (FFKM) can work for a long time at 300 ℃ and is highly inert to media such as fuel, hydraulic oil, strong acids and alkalis. A certain oil drilling equipment manufacturer uses FFKM rubber to manufacture seals. In a corrosive environment containing hydrogen sulfide (H ₂ S) at 250 ℃, the sealing life is three times longer than traditional FKM rubber, and the leakage rate is reduced to less than 0.01%.

 

3. Ethylene propylene rubber and special blend rubber: balance between cost-effectiveness and performance

Ethylene propylene diene monomer (EPDM) is commonly used for sealing automotive cooling systems due to its ozone resistance and aging resistance. By combining with peroxide vulcanization system, EPDM can maintain long-term stability at 150 ℃. The sealing strip of a new energy vehicle battery pack adopts EPDM/silicone rubber blend adhesive, which combines the high temperature resistance of silicone rubber with the cost advantage of EPDM, and has a working life of over 10 years in an electrolyte environment at 175 ℃.

 

2、 Formula design: Collaborative optimization of fillers, vulcanizing agents, and additives

1. Packing system: Improve mechanical performance and thermal stability

The selection of fillers for high-temperature resistant rubber compounds should take into account both reinforcement and thermal stability. White carbon black (SiO ₂) is commonly used for reinforcing silicone rubber due to its high specific surface area and low thermal conductivity. Adding 50 parts of gas-phase white carbon black to a certain aviation seal formula can increase the tensile strength of silicone rubber to 12MPa while reducing the coefficient of thermal expansion. In addition, the addition of high-temperature resistant fillers such as ceramic fibers and aramid fibers can significantly improve the tear resistance and ablation resistance of rubber products. For example, in the sealing of rocket engine nozzles, adding 20% ceramic fiber silicone rubber composite material can maintain structural integrity at 1200 ℃.

 

2. Sulfurization system: control crosslinking density and thermal decomposition

The choice of vulcanizing agent directly affects the thermal stability of rubber. The peroxide vulcanization system (such as DCP) is suitable for high-temperature rubber because its vulcanization product is a carbon carbon bond (C-C), and its thermal decomposition temperature is higher than that of the sulfur vulcanization system. In a certain fluororubber formula, the use of a double-2,5 vulcanization system (BIPB) can increase the thermal decomposition starting temperature of the vulcanized rubber to 350 ℃ at 300 ℃. In addition, adding anti-aging agents (such as RD, MB) can inhibit thermal oxidative degradation and prolong the life of rubber products.

 

3. Additive system: precise regulation of functional additives

High temperature resistant rubber products require the addition of functional additives to cope with special working conditions. For example, adding aluminum hydroxide (ATH) or magnesium hydroxide (MDH) flame retardants to silicone rubber can increase its flame retardant rating to UL94 V-0; Adding graphite or molybdenum disulfide lubricant can reduce the friction coefficient between rubber and metal, making it suitable for sealing high-temperature bearings. After adding 5% graphite lubricant to the sealing ring formula of a certain automobile turbocharger, the friction coefficient decreased to below 0.1 and the wear rate decreased by 40%.

 

3、 Process optimization: full process control from mixing to molding

1. Mixing process: precise control of temperature and shear force

The mixing of high-temperature rubber compound requires strict control of temperature and time. For example, during the mixing of fluororubber, temperatures exceeding 120 ℃ can easily lead to burning. Therefore, a low-temperature slow mixing process should be adopted, and sulfurizing agents and fillers should be added in stages. A certain enterprise has reduced the temperature fluctuation range of the mixing machine to ± 3 ℃ by introducing an intelligent temperature control system, which has improved the dispersion uniformity of the rubber material by 30%.

 

2. Molding process: combination of high-pressure injection and molding technology

High temperature resistant rubber products are often produced through injection molding or compression molding. High pressure injection molding (such as liquid silicone rubber injection machines) can ensure that the rubber material is fully filled in complex molds, reducing bubbles and defects. A certain aviation seal manufacturer uses liquid silicone rubber injection molding technology to achieve a seal size accuracy of ± 0.05mm and increase production efficiency by 50%. Compression molding is suitable for large-sized products, and by optimizing the mold temperature and pressure curve, the density and mechanical properties of the product can be improved.

 

3. Post treatment process: secondary vulcanization and surface treatment

Secondary vulcanization (post vulcanization) can further enhance the thermal stability and mechanical properties of rubber products. For example, after secondary vulcanization at 200 ℃ for 4 hours, the compression deformation rate of fluororubber products can be reduced to below 10%. In terms of surface treatment, plasma treatment or chemical coating can enhance the bonding strength between rubber and metal. A certain enterprise has increased the bonding strength between rubber and aluminum alloy to 12MPa by coating silane coupling agent on the surface of rubber, meeting the sealing requirements under extreme working conditions.

 

4、 Application case: Practical verification from aerospace to industrial equipment

1. Aerospace: Core materials for high-temperature sealing and shock absorption systems

In aviation engines, silicone rubber O-rings need to withstand high temperatures of 200 ℃ and fuel corrosion. After adopting VMQ rubber seals, the leakage rate of a certain type of engine decreased from 0.1% to 0.01%, and the service life was extended to 8000 hours. In spacecraft shock absorber systems, shock absorbers made of fluororubber/nitrile rubber blends can maintain damping performance within the range of -60 ℃ to 250 ℃, effectively reducing the impact of launch vibrations on precision instruments.

 

2. Energy extraction: corrosion-resistant and high-temperature sealing solutions

The seals in oil drilling equipment need to withstand high temperatures of 250 ℃ and corrosive media containing hydrogen sulfide. The FFKM rubber seal developed by a certain enterprise has a working life of over 5000 hours and a leakage rate of less than 0.005% in an environment with a H ₂ S concentration of 1000ppm. In nuclear power plant steam generators, sealing gaskets made of silicone rubber/ceramic fiber composite materials can maintain sealing performance in 350 ℃ and high-pressure steam environments, replacing traditional metal gaskets and reducing leakage risks.

 

3. Automotive industry: the "safety guard" of new energy vehicle battery packs

The battery pack of new energy vehicles needs to be sealed in a high temperature of 175 ℃ and electrolyte environment. A certain enterprise uses EPDM/silicone rubber blend adhesive to make sealing strips. By optimizing the formula and process, the sealing strips can achieve a volume expansion rate of less than 5% and a compression deformation rate of less than 10% after soaking in electrolyte for 1000 hours, meeting the IP67 waterproof level requirements.

 

4. Industrial equipment: Innovative applications of high-temperature bearings and valve seals

In the bearings of high-temperature fans in steel plants, sealing rings made of silicone rubber/graphite composite materials can work at 200 ℃ and high-speed rotation (5000rpm), with a friction coefficient of less than 0.1 and a lifespan three times longer than traditional rubber sealing rings. In chemical valves, fluororubber O-rings can withstand strong acid and alkali corrosion at 300 ℃, with a leakage rate of less than 0.001%, ensuring industrial production safety.

 

5、 Future trend: integration of intelligence and sustainability

With the advancement of Industry 4.0 and green manufacturing, high-temperature resistant rubber compounds and rubber products are developing towards intelligence and sustainability. For example, a self-healing silicone rubber developed by a laboratory introduces dynamic covalent bonds into its molecular chains, allowing the rubber to automatically repair cracks at high temperatures and extend its lifespan to twice that of traditional materials. In addition, the research and development of bio based high-temperature resistant rubber is also accelerating. A certain enterprise has reduced the carbon footprint of the rubber material by 40% by combining natural rubber with bio based plasticizers, and its high-temperature resistance performance is comparable to traditional materials.

 

conclusion

High temperature resistant rubber products have become an indispensable key material under extreme working conditions through material innovation, formula optimization, and process upgrades. From aerospace to energy extraction, from the automotive industry to industrial equipment, high-temperature resistant rubber products are driving technological progress in high-tech fields with their excellent performance and reliability. In the future, with the increasing demand for intelligence and sustainability, high-temperature resistant rubber mixing technology will continue to break through boundaries and provide safer and more efficient solutions for industrial development.