Among the various techniques for sterilizing medical devices and biopharmaceuticals, gamma irradiation remains the most widely used. Alternative radiation sterilization methods are being implemented: high energy electron beam and X-rays.

Understanding that free radicals initiate all changes in polymers during irradiation, ESR was utilized after irradiation to track the characteristics and levels of these radicals.Some of these radicals exhibit a longer lifetime, which can be detected using ESR from days to weeks after irradiation. Monitoring the quantity and identifying the types of radio induced radicals helps to assess the impact of radiation sources on materials and evaluate suitability and processing capability of irradiation technologies.

This study involves a comparative analysis of polymers (i.e. PP, PE, PA, POM, and fluoropolymer) materials that have been exposed to gamma rays, X-rays, and electron beams at different absorbed doses.

The different groups of polymers studied generated characteristic radicals regardless of the irradiation technology used. Among the 31 materials studied, a similar ESR signal and no significant difference in radical concentration were observed between gamma, X-rays, and electron beam irradiation for each group of polymers. The equivalence of the ESR signals, kinetics, and radical concentration for the different classes of polymers studied indicate that a similar radiation-matter interaction can be demonstrated1.

REFERENCE

(1)       Krieguer, B.; Marque, S. R. A.; Dorey, S.; Dupuy, N.; Girard, F.; Girard-Perier, N.; Kuntz, F.; Ludwig, N. Radical Detection and Electron-Spin Resonance (ESR) Monitoring in Polymer Materials Irradiated with Gamma and X-Rays: Polyethylene and Polypropylene. Journal of Applied Polymer Science 2024, e55098.