Effect of γ irradiation on the impact response of rigid polyurethane foam

Abstract

Abstract An experimental study to observe the change in impact response of rigid polyurethane foam due to γ irradiation is presented. The foam samples were irradiated using a 60Co based γ irradiator, γ Chamber 5000. Dynamic tests were performed on unirradiated and irradiated cubical foam specimens in a drop weight testing machine to characterize the mechanical properties. Structural characterization was performed using phase-contrast X-ray imaging and scanning electron microscopy (SEM). The results reveal a significant change in the dynamic response of polyurethane foam after irradiation due to change in structure. The response of foam gets stiffer in the initial linear phase, and densification (lockup) occurs well below the strains at which lockup occurs for an unirradiated foam. The ramifications of this study towards the application of polyurethane foam as an impact limiter in nuclear shipping casks are discussed.