Assessment of the impact of the irradiation process on the final properties of radiation-resistant polypropylene materials used for medical devices

Abstract

The global demand for sterile medical devices is increasing due to technological advancements and growing health care needs. Although Electron beam (EB) and X-ray have existed for a long time, they have been less utilized compared to other sterilization methods such as ethylene oxide and Gamma irradiation. Currently, their application is developing, offering new possibilities in response to a rapidly expanding sterilization market. This study assesses the impact of these irradiation techniques on polypropylene (PP) materials used in medical devices, focusing on their mechanical properties, structural changes, and color stability. PP is known for its sensitivity to irradiation, which makes the evaluation of its properties under different irradiation conditions particularly relevant. Three different PP grades, with varying radiotolerance claims, were exposed to controlled irradiation doses (30, 45, and 85 kGy). Analyses including electron spin resonance (ESR), rheology, tensile testing and colorimetry were carried out. They were also employed in conjunction with principal component analysis (PCA). The results allowed to evaluate irradiation-induced modification. Results indicate that Gamma irradiation induces the most significant degradation due to its low dose rate, leading to increased chain scission and oxidation effects. E-beam irradiation has the least impact, while X-ray effects are generally lower to Gamma irradiation at equivalent doses. The study highlights the importance of selecting appropriate PP formulations to ensure optimal post-irradiation performance, particularly in the context of transitioning from traditional sterilization methods to E-beam or emerging X-ray technology.