Tailoring of the thermal, mechanical and dielectric properties of the polypropylene foams using gamma-irradiation

Abstract

This study investigate the influence of gamma-irradiation (GI) doses from 0 up to 50 kGy on the polypropylene (PP) foams, mainly the impact on their structural and physical properties. It was found that structural properties were not significantly changed and the cellular structure of the PP foams sustain the same, while the thermal properties were significantly enhanced with increasing GI doses, due to the present cross-linking created within the irradiation. The cross-linking was confirmed also by the swelling measurements. The dielectric properties shows the three time increase of capacitance with increasing GI doses, due to the additional charges created in the foam voids by GI. Investigated mechanical properties in case of tensile tests as well as dynamical mechanical analysis proved, that enhanced behaviour was observed only in case of samples with irradiated by low doses, 1 kGy and 5 kGy, respectively, while the higher doses significantly decrease these ones, due to the present scission confirmed by FTIR and other investigations. Finally, it was found the competition between the cross-linking of the PP foam and present scission due to the applied GI and therefore the physical properties can be easily tailored.