A STUDY OF THE STRUCTURE OF PRE-GELLED EPOXY NETWORKS

Ammonium salts of pre-gelled epoxy networks, in the form of spherical clusters, were prepared by the addition of hydrogen chloride in methan ol solution to partially cured bisphenol A diglycidyl ether/ethylene d iamine epoxy resins. The formation of ammonium salts resulted from the interaction of hydrogen chloride with the amine groups of the pre-gel led epoxy networks, as indicated by their infra-red and solid-state C- 13 n.m.r. spectra and X-ray diffraction patterns. By increasing the ti me allowed for branching reactions or by increasing the concentration of branched molecular chains, the spherical clusters tended to form as agglomerations of ribbon textures, which were then demonstrated to be associated with the packing of the branched molecular chains. The pac ked networks could also be detected through X-ray diffraction studies of the post-gelled epoxy resins.