Microwave processing of thermoplastic modified epoxy resin networks

Abstract

Microwave processing has been demonstrated to provide an alternative method to conventional thermal treatments to effectively cure reactive polymeric materials. In the current investigation, a controlled electromagnetic field in a single-mode microwave applicator was utilized to process epoxy resin thermosets. Fully cured networks (as monitored by DSC) were achieved in as little as ten minutes with equivalent mechanical properties to materials cured using three to four hour thermal curing cycles. Phase-separated morphologies ranging from discrete phases of the modifier in an epoxy resin matrix to phase inverted structures consisting of spheres of epoxy embedded in a continuous thermoplastic matrix were achieved as has been previously observed with networks cured with conventional processing techniques. However, with microwave processing it was discovered that the phase separation behavior in these multiphase networks could actually be controlled by varying the processing parameters (ie., the heating rate as governed by the microwave power level).