Differential scanning calorimetry and optical microscopy were used to determine the miscibility behaviour of poly-d(-)(3-hydroxybutyrate) (PHB) and poly(ethylene oxide) (PEO) mixtures. It was found that PHB and PEO are miscible in the melt. Consequently the blend exhibits a single glass transition temperature and a depression of the equilibrium melting temperature of PHB. The study of the isothermal crystallization process shows that at a given crystallization temperature the presence of PEO causes a depression in the growth rate of PHB spherulites. The blend exhibits a phase diagram characterized by the presence, below the apparent melting temperature of PHB and PEO, of interlamellar and/or interfibrillar homogeneous amorphous PHB/PEO mixtures. The Flory-Huggins interaction parameter (?12), obtained from melting point depression data, is composition dependent, and its value is always negative
PolyHydroxybutyrate/polyethyleneoxide blends: phase diagram, thermal and crystallization behaviour
M Avella;
1988
Abstract
Differential scanning calorimetry and optical microscopy were used to determine the miscibility behaviour of poly-d(-)(3-hydroxybutyrate) (PHB) and poly(ethylene oxide) (PEO) mixtures. It was found that PHB and PEO are miscible in the melt. Consequently the blend exhibits a single glass transition temperature and a depression of the equilibrium melting temperature of PHB. The study of the isothermal crystallization process shows that at a given crystallization temperature the presence of PEO causes a depression in the growth rate of PHB spherulites. The blend exhibits a phase diagram characterized by the presence, below the apparent melting temperature of PHB and PEO, of interlamellar and/or interfibrillar homogeneous amorphous PHB/PEO mixtures. The Flory-Huggins interaction parameter (?12), obtained from melting point depression data, is composition dependent, and its value is always negativeI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
