Rubber-Modified Epoxies. I. Cure, Transitions, and Morphology.

摘要

A methodology for investigating cure and its relationship to the development of morphology and transitions for rubber-modified thermosetting systems has been developed. An aromatic tetrafunctional diamine-cured digly-cidyl ether of bisphenol A epoxy resin (maximum glass transition temperature 167 C was modified separately with two reactive liquid rubbers; i.e., a prereacted carboxyl-terminated rubber and an amino-terminated rubber. In order to develop fully cured but distinct cure-dependent morphologies, the systems were cured isothermally at different temperatures until reactions ceased and then were postcured by heating above the maximum glass transition temperature. The maximum glass transition temperature of the matrix and the volume fraction of dispersed phase for the amino-terminated rubber-modified system were particularly sensitive to cure conditions in consequence of complications in the cure chemistry.