Mechanical response of low density expanded polypropylene foams in compression and tension at different loading rates and temperatures

Polymer foams are often used for impact mitigation and protection due to low weight and excellent energy absorbing capability. Depending on the application, different loading rates and environmental conditions can be expected, including various operating temperatures. In this paper, experimental results from mechanical testing of expanded polypropylene (EPP) are presented, focusing on temperature and rate dependence. The compressive and tensile responses of two EPP foams of similar nominal density (30 kg/m3) but different morphology are compared. Both foams were tested in compression at low to intermediate strain rates (10-3 to 100s-1) to determine the strain rate dependence. The temperature dependence of one foam type was quantified in both compression and tension for temperatures between -30°C and 60°C in order to highlight the importance of operating temperature. It was found that both strain rate and temperature have a definitive effect on the mechanical properties. The morphology of the two EPP foams also seems to affect the response.