THE HETEROGENEITY OF THE NETWORK STRUCTURE OF EPOXY POLYMERS STUDIED BY DYNAMIC AND DSC TESTS

The final network structure of epoxy polymers cured with a crosslinking agent is strongly connected with the type and amount of the curing agent and conditions. Concerning the morphology of this network, it has been reported that cured epoxies are two-phase systems, containing roughly spherical floccules arranged in a matrix resembling the constituent phases. In this paper and by using an epoxy-polymer cured with different amounts (i. e. , different than the stoichiometric one) of a curing agent, strong indications of their network-structure heterogeneity have been disclosed. For this study, two different experimental techniques, such as dynamic mechanical measurements and DSC tests have been utilized. It was found that cured epoxy-polymers consist of two extreme regions, with low and high crosslink densities, whose volume fractions have been estimated by using a mechanical model applicable for two-phase systems.