The hygrothermal fatigue induces a complex phenomenology in the epoxy composites, with degradation of the linear coefficients of expansion.
Epoxy composites, (novolac type, with SiO2 as filler, 75–85 % in weight) have been exposed to high temperature and high pressure moisture.
A role important is played by the decomposition products formed during the aging. The Molecular Weight Distribution of these species has been followed by GPC and shows that there is partial depolymerization of the matrix after 24 h treatment time. It has been found that there is surface migration of low Molecular Weight species, both additives and decomposition products.