Compression yielding of epoxy: Strain rate and temperature effect

The response to compressive mechanical loading of the thermosetting system epoxy polymer based on diglycidyl ether of bisphenol A (DGEBA) and an aromatic amine hardener, 4,4′-methylenedianiline (DDM) has been experimentally investigated as a function of strain rate and temperature, ranging from 0.0025 to 2500 s−1 and from room temperature to 100 °C, all below the glass transition temperature. Results showed that both the elastic modulus and the compression strength of the material significantly increased with strain rate and decreased with temperature. Quasi-static tests, performed in electromechanical machines, and dynamic tests, carried out in a Hopkinson bar, were compared and simultaneously analyzed to generate a master curve representative of the material yielding, assuming the strain rate-temperature superposition principle. Experimental data were fitted to equations based on thermally activated models for polymers.