TRANSITION FROM METASTABILITY TO INSTABILITY IN A BINARY-LIQUID MIXTURE

In a binary mixture of oligomers of styrene and caprolactone, we have studied a transition from metastability to instability by changing a quench depth systematically under an off-critical quench condition. The concentration distribution function turns out to be a good fingerprint for determining whether phase separation is nucleation-growth type or spinodal-decomposition type. We also demonstrate clear morphological and kinetice evidence of a diffuse metastable-unstable transition or crossover phenomena theoretically predicted for the system with a finite-range interaction. © 1990 The American Physical Society.