Studies on biodegradability, morphology and thermomechanical properties of LDPE/modified starch blends

Starch was converted to a hydrophobic derivative by phthalation. The starch phthalate (stath) thus obtained was found to show highly crystalline nature and sharp melting point. The potential of stath as a substitute for starch in the development of biodegradable blends was investigated. Blends of LDPE containing up to 30% starch were prepared and the latter was gradually replaced by stath. It was observed that the tensile strength and elongation at break increased while the modulus decreased as the starch was substituted by stath. Morphology of binary LDPE/stath blends showed improved adhesion leading to enhanced mechanical properties compared to LDPE/starch blends. DSC analysis showed no significant change in the T-m of LDPE by incorporation of 30% stath in spite of a wide difference in the T-m of the two components. Biodegradation of starch was found to decrease on esterification. However, the LDPE/stath blends showed greater degradation in soil compared to LDPE/starch blends. (C) 2000 Elsevier Science Ltd. All rights reserved.