Fabrication of Silicone Rubber Foam with Tailored Porous Structures by Supercritical CO2

Abstract

In spite of great concern on the wide application of silicone rubber foams, few works have been reported about easy-operating foaming method. In this study, the effects of silica content and foaming process on the porous structure of high-temperature-vulcanized silicon rubber foams are evaluated, which are prepared by supercritical CO2 at different conditions, with fumed silica used for reinforcement. Silicone rubber foams with cell size in 8–120 μm, cell density in 105–108 cm−3, and density between 0.45 and 0.9 g cm−3 are prepared under different saturation conditions. The results show that increasing silica content can decrease cell size. It is also found that cell density improves exponentially with increasing saturation pressure and decreasing saturation temperature. Besides, it demands less than 1 h for specimens to reach equilibrium on thickness around 3 mm. All the results indicate that the porous structures of silicone foams can be tailored by foaming process parameters facilely and are predictable with fitted equation.