Effects of electron beam sterilization on polyethylene terephthalate: Physico-chemical modifications and formation of non-volatile organic extractables.

Our investigations hereby involve the effects of ionizing radiation as a sterilization method, and especially electron beams, on a medical grade Polyethylene Terephthalate (PET). Ionizing radiations are known to induce free radicals formation in the polymer that will then either degrade or crosslink, depending on its chemical nature, ionizing type and irradiation atmosphere (Charlesby, 1967; Dole, 1972 and Dole, 1973). The evaluation of packaging material modifications under radiation sterilization is of great interest and the objective of our paper is to focus on both PET volume modifications and extractable analyses after electron beam sterilization. As regards the polymeric matrix and after sterilization, we did not observe by means of spectral analyses, any single chemical modification whatsoever, whereas by thermal techniques we evidenced polymer chain scissions. As for the non-volatile organic extractables, we further substantiate the presence of numerous compounds, namely oligomers and trimers especially, along with benzoic and terephthalic acids in particular. With respect to pharmaceutical stakes however, we claim herein that the 25kGy sterilization dose used, triggers oligomers and extractables formation, a result which is promising for further risk analysis.