How do silicone rubber sealing rings become the guardians of elasticity under extreme temperatures?
Publish Time: 2026-02-19
As a key sealing component in industrial equipment, automotive systems, aerospace, and other fields, the performance stability of silicone rubber sealing rings directly affects the safe operation and service life of equipment. Under extreme high and low temperature alternation conditions, the material must withstand temperature ranges from -60℃ to 250℃, making the maintenance of elastic recovery rate and sealing performance a core technical challenge. Drastic temperature fluctuations can alter the molecular chain motion state of the material, leading to hardening, embrittlement, or softening failure. Maintaining stable sealing in harsh environments is a key focus of silicone rubber technology research.1. The Mechanism of Temperature's Influence on Silicone Rubber MaterialsThe main chain of silicone rubber is composed of silicon-oxygen bonds, with bond energies higher than ordinary carbon-carbon bonds, giving it excellent resistance to high and low temperatures. However, extreme temperatures still have a significant impact on the material. At low temperatures, molecular chain motion is restricted, and the elasticity near the glass transition temperature of the material decreases sharply, resulting in hardening and embrittlement. The compression rebound capacity weakens, and insufficient sealing contact pressure leads to leakage. In high-temperature environments, the thermal motion of molecular chains intensifies, and the cross-linked network may undergo thermal degradation or oxidative breakage, leading to increased permanent deformation, decreased hardness, and weakened sealing force. Alternating temperature cycles can further induce thermal stress fatigue, accelerating the material aging process, forming microcracks that gradually propagate, ultimately causing seal failure.2. Material Formulation Optimization: Enhancing Stability at the Molecular LevelThe core of improving the temperature adaptability of silicone rubber sealing rings lies in formulation optimization. The selection of the base polymer is crucial; methyl vinyl silicone rubber with high vinyl content maintains good elasticity over a wide temperature range. The cross-linking system employs peroxide vulcanization or platinum-catalyzed addition vulcanization; the former offers better heat resistance, while the latter results in lower compression set. Regarding fillers, fumed silica can enhance mechanical properties, but surface treatment is required to improve dispersibility and prevent filler-rubber interface debonding at low temperatures. Adding heat-resistant additives such as iron oxide and cerium oxide can capture free radicals generated at high temperatures, delaying thermo-oxidative aging. Low-temperature plasticizers such as low-molecular-weight silicone oils can lower the glass transition temperature and improve low-temperature flexibility. Precise formulation balance enables the material to maintain appropriate molecular chain mobility even under extreme temperatures.3. Structural Design and Process Control: Performance Assurance at the Engineering LevelThe geometric design of the sealing ring significantly impacts its temperature adaptability. The cross-sectional shape, whether circular or irregular, must account for dimensional changes due to thermal expansion and contraction, allowing for adequate compression compensation. Groove design should ensure the sealing ring maintains minimum contact pressure during low-temperature contraction and prevents excessive compression leading to permanent deformation during high-temperature expansion. In the production process, precise control of vulcanization temperature and time determines the uniformity of cross-linking density; under-vulcanization results in insufficient heat resistance, while over-vulcanization reduces elasticity. Secondary vulcanization removes low-molecular-weight volatiles, improving high-temperature stability. Mold precision and the selection of release agents affect surface quality, reduce stress concentration points, and delay fatigue crack initiation.The performance stability of the silicone rubber sealing ring under extreme high and low temperature alternating conditions is a comprehensive result of materials science, formulation technology, and engineering design. From molecular chain structure optimization to macroscopic geometric design, from production process control to full-temperature range testing and verification, every step is designed to ensure the reliability of the seal.
