Characterization of polyhydroxybutyrate-hydroxyvalerate (PHB-HV)/maize starch blend films

Blends of polyhydroxybutyrate-hydroxyvalerate (PHB-HV) with maize starch at starch contents of 0%, 20%, 30%, 40% and 50% were prepared by casting. The morphological and molecular properties were investigated by using Fourier transform infrared spectrometry, optical microscopy and scanning electron microscopy (SEM). The Young’s modulus, strength, strain to break obtained by tensile deformation, and puncture force decreased with an increase in starch content. FT-IR measurements indicated that no intermolecular interactions existed between the two polymers as no shift in the absorption peaks of the PHB-HV or starch in the blends was observed, which suggests that PHB-HV and starch are immiscible. Optical micrographs of PHB-HV/starch blend films did not show complete melting during blending. The blends showed a lack of interfacial adhesion between starch and PHB-HV and heterogeneous dispersion of starch granules over the PHB-HV-rich matrix, as evidenced by SEM and optical micrographs of the surface.