Highly water resistant cassava starch/poly(vinyl alcohol) films

Biodegradable films were prepared based on cassava starch (CS) and poly(vinyl alcohol) (PVA). To increase its tensile strength and flexibility, CS (20-60 wt%) was blended with PVA at various weight ratios (80-40 wt%). Triethylamine (TEA) was added as a homogeneous catalyst to increase intermolecular interaction and induce miscibility between CS and PVA. The crystallinity and hydrophobicity of blend films containing 20 wt% CS were promoted by the elimination of residual acetate groups in PVA. The number of hydrogen bonds in these blend films increased, which led to stronger interaction and more compact molecular packing between CS and PVA chains. The poor water resistance that limits the shelf-life and applications of CS blends was improved. The addition of TEA to blend films containing 20 wt% CS increased water resistance by 80% and tensile strength by as much as 440%. The development of greater structural integrity yielded ecologically sustainable, low-cost, biodegradable films with excellent physical and mechanical properties.