Crystallization and morphology of poly(ethylene succinate) and poly(beta-hydroxybutyrate) blends

The melting and crystallization behavior of poly(beta-hydroxybutyrate) (PHB ) and poly(ethylene succinate) blends has been studied by differential scan ning calorimetry and optical microscopy. The results indicate that PHB and PES are miscible in the melt. Consequently the blend exhibits a depression of the melting temperature of both PHB and PES. In addition, a depression o f the equilibrium melting temperature of PHB is observed. The Flory-Huggins interaction parameter (chi(12)), obtained from melting point depression da ta, is composition dependent, and its value is always negative. Isothermal crystallization in the miscible blend system PES/PHB is examined by polariz ed optical microscope. The presence of the PES component gives a wide varie ty of morphologies. The spherulites exhibit a banded structure and the band spacing decreases with increase PES content.