Radiation effects on polypropylene for sterilization

In order to improve the resistance of gamma-radiation sterilization of polypropylene (PP), the formulations of the additives such as antioxidants, crosslinking agent, and trans-stilbene oxide (StO) have been carried out. The irradiated PP and ethylene-propylene copolymer samples with control and additives were characterized by mechanical tester, colorimetry, and Fourier transform infrared spectroscopy with total attenuated reflectance mode (FTIR-ATR). Crosslinking agent and StO formulated PP showed remarkable radiation resistance and minimum discoloration. Also, radiation resistance of ethylene-propylene copolymers with 3% of ethylene contents was better than that of PP homopolymers in the case of no additives. The proposed mechanisms of radiation stabilization with additives are also discussed.