Biodegradable films from PHB-8HV copolymers and polyalcohols blends: crystallinity, dynamic mechanical analysis and tensile properties

Blends of poly(3-hydroxybutyrate)-poly(3-hydroxyvalerate) (PHB-HV) and poly alcohols have been prepared by solvent casting. The polyalcohols used were castor oil (CO) and polypropylene glycol (PPG400 and PPG1000). Thermal beha viour, crystallinity, morphology and dynamic mechanical properties of syste ms with various PPG1000 compositions have been studied. Crystallinity was d etermined by means of Fourier transform infrared spectroscopy (FTIR) and X- ray diffraction. Final morphology was studied by means of scanning electron microscopy (SEM). Dynamical mechanical analysis showed two glass transitio n temperatures for the blends, corresponding to separate phases of PHB-HV a nd polyalcohols. Blend immiscibility was found. Polyalcohol addition enhanc es the crystallinity of PHB-HV. However, the storage modulus value decrease s, upon the addition of amorphous compound. (C) 1999 Society of Chemical In dustry.