Mechanical–Microstructure Relationship and Cellular Failure Mechanism of Silicone Rubber Foam by the Cell Microstructure Designed in Supercritical CO₂

Abstract

Considering the frequent use of silicone rubber foam under stress in actual application, it is vital to study the relationship between the cell microstructure and mechanical properties of silicone rubber foam. Herein, silicone rubber foams with different cell morphologies (spherical cells and polygonal cells), porosities (from 51.4 to 82.6%), and average cell sizes (from 5 to 266 μm) have been designed by supercritical CO2 foaming. The mechanical properties and cellular failure mechanism of silicone rubber foams have been investigated to analyze the effect of cell microstructures on performances. Compared with silicone rubber foam with small cell size (<10 μm), the foam with large cells (>50 μm) shows obviously reduced compressive stress, with significantly improved elastic recovery performance (the permanent compression set at 70 °C decreased from 84.8 to 1.5%). In addition, silicone rubber foam with moderate cell size (about 50 μm) had the largest tensile strength and elongation at break. These results indicated that the cellular structure had a great influence on the mechanical properties of silicone rubber foam, providing a direction to design the cellular structure of silicone rubber foam based on its practical application.