NANOSTRUCTURAL CHARACTERIZATION OF RADIATION- CURED EPOXY ACRYLATE NETWORKS

摘要

The micro structure of epoxy diacrylate networks obtained by radiation-initiated cross-linking polymerization was investigated by physical methods providing complementary information on networks heterogeneities. AFM imaging of the networks in the tapping mode provided phase contrast pictures revealing the presence of nanosized heterogeneities interpreted in terms of hard clusters initially generated in continuous matrix of a softer network. The calorimetric features of the two types of domains were determined by TMDSC analysis of samples prepared by UV- or by EB-induced polymerization. The influence of acrylate conversion on the relaxation behavior of cured samples was examined to describe the gradual evolution of the heterogeneities, in terms of local mobility and associated fraction of material, as the radiation-induced polymerization proceeds of the soft and rigid domains. The results can be analyzed according to a 2-component model describing satisfactorily the global behavior. At a given level of monomer conversion, no significant influence of the initiation mechanism and/or curing conditions was observed.