Degradation of epoxy resins under high energy electron beam irradiation:: Radio-oxidation

The degradation of two epoxy systems exposed to electron beam irradiation in oxygen atmosphere has been studied and compared to our previous results obtained under helium atmosphere. A multi-scale approach to the degradation has been carried out using a variety of analytical methods including solid state NMR spectroscopy, 2D-WISE experiments, SEC measurements and infrared spectroscopy associated with chemical derivatisation treatments. It is shown that the degradation of both polymers is governed by radiolytic processes which involve chain scissions. The formation of oxidation products, mainly carboxylic acid chain ends, was shown at the surface of the irradiated film. Oxidative degradation is limited to the first 20 mu m of the film due to the low oxygen diffusion coefficient in epoxy polymers combined with the high dose rates of irradiation. (C) 2007 Published by Elsevier Ltd.