MORPHOLOGY DEVELOPMENT IN EPOXY POLYMER SYSTEMS - THERMOSETTING EPOXYMICRO PARTICLES WITH A THERMOPLASTIC SHELL/

A novel method based on phase inversion and inter-boundary reaction in a reactive system comprising a thermoplastic phenoxy and a thermosett ing epoxy has been proposed to design micro epoxy particles with a the rmoplastic polymer shell. Due to the hydroxyl group in phenoxy, inter- domain reactions were found to lead to a chemical link between the pol ymer and the epoxy network. As cure progressed, the phenoxy component was first expelled out of the epoxy spheres at initial stages of cure and a phase-separated morphology was set. Subsequently, the pendant -O H groups in the phenoxy shells were grafted onto the outer surfaces of the epoxy core particles (3-4 mu m) at high enough temperatures (187 degrees C or higher) during later stages of cure. This paper describes the mechanisms and fundamental phenomenon under which this unique met hod of preparing polymer/epoxy spheres (epoxy cores/phenoxy shell) of controlled sizes can be realized. Several factors have been found to a ffect the geometry of the epoxy spheres and the chemical bondings betw een the polymer and epoxy. (C) 1997 Elsevier Science Ltd.