Effect of ionizing radiation on the physicochemical and functional properties of silicone rubber and silicone foley catheter

The utilization of ionizing radiation, such as gamma ray and electron beam, in medical product sterilization has seen significant growth in recent years, driven by concerns regarding the safety of ethylene oxide sterilization. This paper examines the effects of these radiation modalities on silicone rubber, and its applicability on a silicone rubber-containing medical device, specifically a silicone foley catheter, by assessing its functional properties before and after irradiation at varying absorbed doses.Analysis of the irradiated samples revealed the presence of carbonyl groups, indicating radiation-induced oxidation. Gamma irradiation did not exhibit fundamental changes in the polymer structure but showed degradation at higher temperatures due to oxidation mechanisms. Moreover, a significant decrease in elongation at break was observed indicating that the already highly crosslinked silicone rubber experienced additional crosslinking affecting its mechanical properties. In contrast, both irradiations led to degradation, as evidenced by a decrease in TG residue. However, the mechanical properties, including tensile strength and elongation at break, were less affected. This suggests limited crosslinking and fragmentation of the polymer backbone. At a lower dose, a decrease in both strength and elongation indicated the formation of branched structures, limiting mobility, introducing irregularities, and weakening the polymer's overall strength. Despite these effects, the functional properties of the silicone foley catheter were practically unaffected at low absorbed doses, except for the discoloration of the syringe ports. Overall, the study provides insights into the effects of ionizing radiation on silicone rubber, highlighting the complex interplay between crosslinking, chain scission, and oxidation mechanisms. The findings contribute to understanding the changes in the polymer's structure and properties under different radiation modalities and doses, facilitating the development of effective sterilization techniques for medical devices containing silicone rubber.