REACTION-INDUCED PHASE-SEPARATION IN RUBBER-MODIFIED EPOXY-RESIN

The phase separation mechanism and structure development during curing of epoxy with a novel liquid rubber-ZR were investigated by time-reso lved light scattering, optical microscope and differential scanning ca lorimetry (DSC). The mixture loaded with curing agent was a single-pha se system in the early stage of curing. When the cure reaction proceed ed, phase separation took place via the spinodal decomposition induced by polymerization of epoxy resin. This was supported by the character istic change of light scattering profile with curing time. Cure reacti on plays an important role in the progress of phase separation. The bi gger the cure reaction rate is, the longer periodic distance will be. The overall two-phase structure was basically locked in when the conve rsion approached 80% estimated by DSC, and finally the co-continuous t wo-phase structure was successfully obtained.