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-resolved light scattering, optical microscope and differential scanning calorimetry (DSC). The mixture loaded with curing agent was a single-phase system in the early stage of curing. When the cure reaction proceeded, phase separation took place via the spinodal decomposition induced by polymerization of epoxy resin. This was supported by the characteristic change of light scattering profile with curing time. Cure reaction plays an important role in the progress of phase separation. The bigger the cure reaction rate is, the longer periodic distance will be. The overall two-phase structure was basically locked in when the conversion approached 80% estimated by DSC, and finally the co-continuous two-phase structure was successfully obtained.