POLYMER-POLYMER AND COPOLYMER COPOLYMER MISCIBILITY IN BLENDS - A MORPHOLOGICAL-STUDY

Curves of instantaneous copolymer composition vs. fractional conversion have been calculated for the copolymerization of N-vinyl-2-pyrrolidone (VP) with n-butyl acrylate (BA). Low conversion samples of poly(VP-co-BA) possessing minimal heterogeneity in composition, were blended in appropriate proportions so as to simulate the cumulative copolymer compositions produced at various levels of conversion in an actual copolymerization. The phase behavior of these blends has been examined by electron microscopy. The results show that the miscibility between the copolymers within each blend is limited and is a consequence of the compositional heterogeneity predicted from the calculated curves. A morphological study for a series of blends of the homopolymers PVP and PBA was also effected and is discussed.