Effects of radiation type and dose on the properties of selected polymers

Using ionizing radiation to sterilize medical and health care products is a widespread and well established approach, as products can be treated in their final shipping container without any residuals. During irradiation, the product materials will undergo some changes due to the absorbed energy, which have to be assessed during product qualification in order to specify a maximum allowable dose for the product. However, there is a lack of a systematic approach studying polymers in regard to dose ranges encountered and all types of ionizing radiation. Therefore, the aim of this work was to investigate the influence of radiation dose and source on the resulting properties of various polymers, which were already brought into final shape via injection molding, and to compare these effects found in the mechanical and rheological properties as well as their appearance. We found, that the mechanical properties of most investigated polymers are not influenced, except for polypropylene, but that yellowing was a pronounced effect in all the cases. The differences in polymer properties due to the radiation sources are small, only some materials exhibit more degradation by gamma irradiation due to the lower dose rate applied in comparison to x-ray and e-beam irradiation.