High melting thermoplastic/epoxy resin blends: Influence of the curing reaction on the crystallization and melting Behavior

The influence of the cure process and the resulting reaction-induced phase separation (RIPS) on the crystallization and melting behavior of polyoxymethylene (POM) in epoxy resin diglycidylether of bisphenol A (DGEBA) blends has been studied at different cure temperatures (180 and 145 degrees C). The crystallization and melting behavior of POM was studied with DSC and the simultaneous blend morphology changes were studied using OM. At first, the influence of the epoxy monomer on the dynamically crystallized POM was investigated. Secondly, a cure temperature above the melting point of POM (T(cure) = 180 degrees C) was applied for blends with curing agent to study the influence of resulting phase morphology types on the crystallization behavior of POM in the epoxy blends. Large differences between particle/matrix and phase-inverted structures have been observed. Thirdly, the cure temperature was lowered below the melting temperature of POM, inducing isothermal crystallization prior to RIPS. As a consequence, a distinction was made between dynamically and isothermally crystallized POM. Concerning the dynamically crystallized material, a clear difference could be made between the material crystallized in the homogeneous sample and that crystallized in the phase-separated structures. The isothermally crystallized POM was to a large extent influenced by the conversion degree of the epoxy resin. (c) 2007 Wiley Periodicals, Inc.