COMPATIBILITY OF POLY(3-HYDROXYBUTYRATE) POLY(ETHYLENE-CO-VINYL ACETATE) BLENDS/

The miscibility of poly(3-hydroxybutyrate) (PHB) with ethylene-vinyl a cetate (EVA) copolymers containing 70 or 85 wt% of vinyl acetate was i nvestigated. The blend of PHB and EVA70 was found to be immiscible, be cause the glass transition temperature, the melting temperature and th e spherulite growth rate under the isothermal crystallization conditio ns were independent of the blend composition. However, the melting tem perature, the spherulite growth rate and the equilibrium melting tempe rature of the PHB/EVA85 blend decreased with an increase in the EVA85 content and the Flory-Huggins interaction parameter of the blend was n egative. Therefore, PHB was found to be miscible with EVA85. (C) 1998 Elsevier Science Ltd. All rights reserved.