Design of lightweight silicone rubber foam for outstanding deformation recoverability based on supercritical CO2 foaming technology

Foams with light weight and low compression set are of great importance for shock absorption materials employed in cushioning, pad, body protection and precision instruments. Silicone rubber foams with different cell sizes were designed via supercritical CO2 (scCO2) foaming technology, the correlations between cellular structure and compression properties including surface hardness, compression deformation resistance, permanent compression set and compression resilience capacity were systematically investigated. Results showed that as the cell size increased, the hardness and maximum compressive stress of silicone rubber foams became lower, meanwhile, stress–strain curve exhibited prolonged plateau region. From the compression-resilience testing, it could be concluded that proper cell size increasement could improve deformation recovery capability of silicone rubber foams, simultaneously reduce permanent compression set and shorten recovery time. Besides, 50 cycles of loading–unloading compression tests were conducted to confirm proper cell size of silicone rubber foam employed in cyclic stress environment.