Comparative studies of starch blends on the properties of PVA films

Abstract

This research studied the effects of pregelatinized starch (PST) and hydrolyzed starch (HST) at various contents with 20 phr glycerol on the properties of polyvinyl alcohol (PVA) film. FTIR analysis showed that the increase of HST preferably interacted with the hydroxyl (OH) groups and CH molecules, while the interaction of hydrogen bonding with PST interacted with OH groups of PVA, but did not affect CH stretching molecules. The blend with HST possessed lower overall thermal degradation than the blend with PST. Tensile strength by blending with PST increased from 14 MPa to 30 MPa, while the elongation at break decreased by a factor of two. On the other hand, elongation at break of the blends with HST improved from 300 (when no HST) to 350%, and its tensile strength improved slightly only with 10 and 20% blending. Regarding the water-soluble properties, hydrogen bonding interaction of starch, PVA and glycerol showed hardly any effect on the rate of dissolving the blends. However, the chemical structure of starch and the size of molecules, especially in HST dramatically increased the rate of dissolving in water.