Long-Term Impact of Sterilization Cycles on the Surface and Mechanical Integrity of Medical-Grade Silicone

This study investigates the effects of repeated cleaning, disinfection, and sterilization cycles on the surface and mechanical properties of medical-grade silicone, including both pure silicone and silicone–steel composite samples. Given the critical importance of sterilization for infection control, understanding its long-term impact on material performance is essential. Samples were subjected to up to 1000 cycles, with evaluations at the initial state and after 200, 500, and 1000 cycles. The contact angle initially decreased from 117.1° to 104.0° after 200 cycles, then gradually increased, approaching the original value after 1000 cycles, likely due to the removal of degraded surface layers. Hardness measurements showed a steady increase at each stage, with an approximate 5% rise per cycle group. Notch growth testing revealed a sixfold increase in crack length after 200 cycles and a twofold increase between 500 and 1000 cycles, indicating substantial loss of mechanical integrity. Optical microscopy of the silicone–steel interface revealed progressive deterioration, including crack formation, erosion, and partial debonding, particularly after 1000 cycles. These findings highlight the material and interfacial vulnerabilities of silicone-based medical devices under prolonged sterilization protocols.