Effect of thermal characteristics of different plasticisers for PVOH/sago SS blends and its weight loss degradation upon soil burial

Abstract

In this study of polyvinyl alcohol (PVOH)/SS were blended with two types of natural-based plasticizers namely, Epoxidized Soybean Oil (ESO) and Sorbitol. Thermal characteristics encompassing gelation temperature of sago starch (SS) and their enthalpy were investigated. For soil burial exposure, films were buried and weight loss for before and after two weeks were followed; the samples were exposed to soil burial tests on Malaysian soil with humidity not less than 70%. Degradation stage of the film was followed via their weight loss. From soil burial tests, the weight loss showed the degradation rate is much faster for sorbitol based blend system. Phase morphology of PVOH/SS plasticizers was viewed via Scanning Electron Microscope (SEM). From the DSC thermograph, the enthalpy formation of the ESO/ Starch is much greater than with Sorbitol and the onset of gelation were much lower for ESO SS blend. From soil burial tests, the weight loss showed the degradation rate is much faster for PVOH/ SS blend of 30:70 composition using ESO, while for sorbitol the degradation is much faster using 20:70 composition. It was found out that, the use of two different plasticisers can alter the degradation rate of the PVOH SS. From the SEM, plasticizing with ESO showed good ESO compatibility with PVOH that gives good strength.