Polyurethane‐crosslinked epoxy resins. II. Compatibility and morphology

Abstract

AbstractThe polyurethane(PU)‐crosslinked diglycidyl ether of bisphenol A (DGEBA) was prepared from the reaction of the pendent secondary hydroxy group in DGEBA with the isocyanate‐terminated group present in the PU prepolymer. Though the PU acted as a crosslinking agent for the DGEBA, the morphology and dynamic mechanical behaviour of these PU‐crosslinked DGEBA could be different among themselves depending on the type and molecular weight of polyols employed in the PU. There was no significant shift in the loss modulus (E″) peaks of the DGEBA crosslinked with the polyester‐type and polyether‐type polyurethanes, but the intensity of the E″ peaks increased as the polyester‐type PU employed. The morphology of this polyester‐type PU‐crosslinked DGEBA exhibited a homogeneous one‐phase system, while the DGEBA crosslinked with the polyether‐type PU showed a two‐phase morphology with the PU particles dispersed in DGEBA matrix.