Epoxy-amine reticulates observed by infrared spectrometry. III. Modifications of the structure and hydration abilities after irradiation in a humid atmosphere

This article is the third part of a series devoted to the study of the resp onsibilities of both humidity and irradiation in the aging process of amine -cured epoxy resins. The basic technique used in this study was infrared sp ectrometry. In previous articles, we described the hydration of two kinds o f epoxy resins widely used in the nuclear industry. In the first article, w e reported results concerning the hydration of unirradiated resins; in the second article, these resins were first submitted to ionizing radiation in a dry atmosphere. In this article, we describe the effects of irradiation i n a humid atmosphere and compare these effects to what was observed after i rradiation in a dry atmosphere, as described in the previous articles. Thes e effects were subtle: the humidity of the ambient atmosphere apparently pr otected the resins from oxidative degradation because, after irradiation in a humid atmosphere, a smaller number of carboxylic groups were formed. How ever, the water uptake increased after irradiation in a humid atmosphere. T hus, the humidity of the ambient atmosphere at the same time favored the ru pture of chains, which released steric hindrances and allowed a greater num ber of H2O molecules to reach hydrophilic sites in the resin. (C) 2001 John Wiley & Sons, Inc.