EFFECT OF THERMAL HISTORY ON WATER SORPTION, ELASTIC PROPERTIES AND THE GLASS-TRANSITION OF EPOXY-RESINS

The DGEBA/TETA (diglycidyl ether of bisphenol-A/triethylene tetramine) system was examined in postcuring conditions at 100°C for 3 and 6 days. Sorption kinetics and equilibria at different temperatures and mechanical tests have been performed on the two sets of samples. Thermal treatment of the epoxy resin containing sorbed water affects its subsequent water sorption characteristics, elastic modulus and glass transition temperature. Attention has also been given to the effects on solubility on thermal history in the presence of water. It was observed that the saturation values in such systems are determined once the higher temperature of the thermal cycle is defined. The differences in solubility of samples with different hygrothermal history are explained in terms of microcavities that can be formed by effect of crazing in the plasticized system exposed to high temperatures. © 1979.