High moisture strength of cassava starch/polyvinyl alcohol-compatible blends for the packaging and agricultural sectors

Abstract

This study aimed to evaluate the thermal, mechanical, physical, structural and morphological properties of new polymeric mixtures based on cassava starch (CMS) and polyvinyl alcohol (PVA) in the proportions of 0/100, 20/80, 40/60, 50/50, 60/40, 80/20 and 100/0 using the casting method. The polymer concentrations and choice of plasticizer were defined after preliminary tests. Mechanical tests revealed that blends became more flexible and ductile with increasing the PVA proportion. The spectroscopy analysis showed significant alterations on the positions and intensity of the bands in 2920, 1415, 1150, 1077, 927 and 848 cm−1, thus indicating a good compatibility among the polymers. Increase of the CMS proportion was reduced until reaching 45 % of the values of water vapor permeability (WVP) in relation to PVA biofilm. Any of the combinations was enough to make the blend less permeable than the CMS biofilm. After increasing the CMS proportions, all blends were more soluble in water compared to PVA biofilm. The exception was the 20P80A blend. Besides representing a tendency of higher opacity, all blends with elevated CMS proportions were more thermally stable when compared to those with the same proportions of PVA. Results showed the potential of such blends for applications on sectors of plastic and agricultural packages.