Degradation of segmented poly(etherurethane) Tecoflex® induced by electron beam irradiation:: Characterization and evaluation

We have studied the influence of electron beam irradiation on a polyurethane Tecoflex((R)) (TFX) used in medical applications: this study has been performed in order to evaluate the capability of such materials to be sterilized by electrons in industrial conditions. With this aim. thin films have been prepared and have been irradiated under a dose-rate of 5 MGy h(-1), with absorbed doses varying from 25 to 1000 kGy under O-2. Analytical techniques used were size exclusion chromatography (SEC) and Fourier transform infrared spectroscopy (FTIR). Evolved gas analysis has been performed using thermogravimetric analysis (TGA) coupled with FTIR spectroscopy (TG-FTIR). TFX films analyzed by SEC showed simultaneous scission and cross-linking that were both increasing with the irradiation dose. Various modifications of FTIR spectra were induced. with appearance of oxidation groups, identified as mainly formates, esters and carboxylic acids. Scission of chains were localized in soft (SS) and hard (HS) segments by decrease of both urethane and aliphatic ether absorbance. Finally, TG-FTIR analysis confirmed previous results: TG analysis of non-irradiated films showed a two-steps profile that was globally shifted to lower temperatures after irradiation. The coupling with FTIR allowed identification of degradation molecules: (i) oxidized SS fragments, (ii) long SS slightly oxidized and (iii) HS accompanied by SS. (C) 2001 Elsevier Science B.V. All rights reserved.