Features of liquid and amorphous-crystalline phase separation processes in block copolymers and in mixtures with variable molecular weights

Abstract

Curves of brightening (clearing) in polymer-polymer systems with variable MW of the components are discussed from a geometrical standpoint. Anomalies in the form of minima are possible because curves of brightening in these systems are determined by the polynodal, whereas in the systems where composition and MW are mutually independent the curve is determined by the binodal. The curves measured for PEO-polyarylate systems by an optical method, where changes in composition occur as a result of a change in MW, are similar to curves for systems with an upper critical temperature of dissolution. However, no anomalies appear on these curves. Preheating of the mixture of 5:90 composition above the binodal results in crystallization taking place, on subsequent cooling to 290 K, spontaneously from single phase solution without any preliminary separation into two amorphoyus phases.