Cure kinetics and phase separation behavior in the phenolic resin/poly(methyl methacrylate) blends

Single-phase mixtures of phenolic derivatives with poly(methyl methacrylate) (PMMA) were cured in the presence of hexamethylenetetramine and the effects of crosslinking density of phenolic resins and molecular weight of PMMA on the phase separation and the reaction kinetics during curing were investigated by light scattering, differential scanning calorimetry and optical microscopy. The time variation of light scattering profiles during curing demonstrated the development of characteristic feature for spinodal decomposition. The observation with optical microscope revealed that co-continuous two-phase structure appeared after a certain time lag and coarsened to a spherical domain structure consisting of phenolic-rich domains dispersed in PMMA matrix. The periodic distances in the phase-separated structure changed with time: the lower the fraction of multi-functional phenolic in total phenols, the larger the periodic distance.