ABSTRACT
Mechanisms and dynamics of phase decomposition following polymerization-induced phase separation (PIPS) of thermoset/thermoplastic blends have been investigated. The phenomenon of PIPS is a non-linear dynamic process that involves competition between reaction kinetics and phase separation dynamics. The mechanism of PIPS has been thought to be a nucleation and growth (NG) originally, however, newer results indicate spinodal decomposition (SD). In PIPS, the coexistence curve generally passes through the reaction temperature at off-critical 92points, thus phase separation must be initiated first in the metastable region where nucleation occurs. When the system further drifts from the metastable to the unstable region, the NG structure transforms to the SD bicontinuous morphology. The crossover behavior of PIPS may be called nucleation initiated spinodal decomposition (NISD) so that it can be distinguished from the conventional SD. The formation of newer domains between the existing ones is responsible for the early stage of PIPS. Since PIPS is a non-equilibrium kinetic process, it would not be surprising to discern either NG or SD textures.
