Effects of foaming variables on density and morphology of expanded ethylene–propylene terpolymers



An experimental study of the relationships between foaming variables and foamed structures of expanded ethylene–propylene terpolymer (EPDM) is reported. The study was carried out using EPDM composition containing azobisformamide blowing agent. The compositions were expanded and cured in hot air into a foamed structure consisting of dense skin and foamed core. The results showed that the foam density, skin thickness, average cell size, and number of cells of the expanded rubbers can be controlled closely by the foaming variables such as residence time, foaming temperature, and blowing agent concentration.