Determination of thermal stability and activation energy of polyvinyl alcohol-cassava starch blends

The thermal degradation and activation energy of polyvinyl alcohol (PVOH) blends with cassava starch (CSV) were investigated by thermogravimetry method. Neat PVOH, CSV and PVOH-CSV specimens were prepared by solution casting method. Thermogravimetry is able to provide a clear description about the thermal resistance of PVOH-starch by comparing the onset degradation temperatures and activation energies of neat PVOH, CSV and PVOH-CSV blends (20-50 wt.% of PVOH). The results showed that neat CSV has better thermal resistance than neat PVOH. This is probably due to the presence of cyclic hemiacetal structure in starch is sustainable to thermal attacks. PVOH-CSV blend exhibits enhancement in thermal stability at 40-50 wt.% of PVOH. The activation energies of 40 and 50 wt.% of PVOH loading in CSV are 149.64 and 175.49 kJ/mol, which are 5.47% and 23.69% higher than CSV, respectively. In short, blending of cassava starch with PVOH significantly improved the thermal stability of PVOH. (C) 2010 Elsevier Ltd. All rights reserved.