SOME PROPERTIES OF POLY(3-HYDROXYBUTYRATE)-POLY(3-HYDROXYVALERATE) BLENDS

The melting, crystallization and dynamic mechanical behaviour of blend s of bacterially produced poly[D(-)-3-hydroxybutyrate] (PHB) and poly[ D(-)-3-hydroxyvalerate] (PHV) have been investigated. Results showed t hat melt-pressed PHB-PHV blends contained phase-separated domains in t he melt which subsequently crystallized as PHB and PHV type spherulite s respectively. The two melting regions detected by DTA related to sep arate melting of PHB and PHV crystallites, which were almost unaffecte d by the blend composition. The mechanical behaviour of a random copol ymer of PHB/HV was compared with that of a blend of almost the same co mposition, and found to be markedly different.