Systematic Formulation Optimization Unlocks High-Temperature Limits of Fluorosilicone Rubber for Long-Term 200°C Service

A comprehensive research breakthrough from China's National Organic Silicone Engineering Technology Center has systematically elucidated the key factors governing the thermal stability of fluorosilicone rubber (FSR), paving the way for next-generation high-performance sealing solutions.

The study reveals that both vinyl content and molecular weight of fluorosilicone raw gum critically influence thermal aging resistance. Higher vinyl content increases crosslinking density, suppressing molecular chain degradation under elevated temperatures. However, this comes with trade-offs in hardness and elongation, leading researchers to recommend a blended approach using both high and low vinyl content gums to balance properties .

Fumed silica selection is equally crucial. The research finds that silica with moderate specific surface area yields optimal mechanical properties both before and after thermal aging, avoiding the deficiencies of low-surface-area or high-surface-area alternatives.

Silane coupling agents, particularly γ-aminopropyltriethoxysilane (KH550), demonstrated superior performance in enhancing tensile strength, tear strength, and—most notably—reducing compression set, a critical parameter for sealing applications. KH550 also improved oil resistance.

The most striking finding involves heat-resistant additives: a CeO₂ and TiO₂ compound system significantly extends the service life of fluorosilicone rubber under high-temperature conditions. This formulation breakthrough is expected to enable fluorosilicone rubber to reliably serve in extreme environments such as aircraft engine accessory systems, turbocharger ducts, and deep-well drilling equipment.

Industry analysts project that commercial products based on this research will enter the market in late 2026, driving the entire sector toward higher performance benchmarks.