DEPENDENCE OF DYNAMIC-MECHANICAL BEHAVIOR OF DGEBA DDM STOICHIOMETRICEPOXY SYSTEMS ON THE CONDITIONS OF CURING PROCESS/

Dynamic viscoelastic properties of diglycidyl ether of bisphenol A (DG EBA) cured with diaminodiphenylmethane (DDM) have been studied. The re laxation spectra of stoichiometric mixtures have been investigated as a function of the casting procedure and the thermal history during cur ing. Variations on the temperatures of the loss peaks and also on thei r magnitude have been observed when a solvent was employed to cast the mixtures. These variations have been attributed to the existence of h igh crosslinked regions formed at the earlier stage of curing inside t he overall matrix. The results obtained from mixtures cured with diffe rent thermal histories underline the importance of adequate selection of curing conditions in order to obtain the optimum properties for the se materials. Differences in crosslink density amongst the mixtures cu red at different conditions have been correlated to the extent of reac tion obtained by infrared measurements. (C) 1995 John Wiley & Sons, In c.