Poly(vinyl alcohol)/modified cassava starch blends plasticized with glycerol and sorbitol

Abstract

A series of blend films comprised 88% hydrolyzed poly(vinyl alcohol) (PVA) with native cassava starch (NCS), high-oxidized cassava starch (HCS), and pre-gelatinized cassava starch (PCS) was prepared via solution casting. The blends were plasticized with glycerol or glycerol-sorbitol mixture. The structure of each blend film was characterized by Fourier-transform infrared spectroscopy and X-ray diffraction analysis. Cross-sections of the PVA/HCS and PVA/PCS blend films, imaged by scanning electron microscopy, indicated a PVA-rich/starch-rich bilayer structure, irrespective of the type of plasticizer in the blend. High degree of swelling of the blend films resulted to the fast degradation. All blend films were completely degraded in soil after 4 days. Significantly, we identified a number of blend films showed greater strength and elongation at break than low density polyethylene, suggesting that these environmentally benign blends could be ideal candidates for widespread applications currently dominated by petroleum-derived products.