Thermal and surface characterization of plasticized starch polyvinyl alcohol blends crosslinked with epichlorohydrin

Starch-polyvinyl alcohol (PVA) blends in 2:8 wt% were prepared with various plasticizers such as polyethylene glycol (PEG-200, PEG-400) and glycerol. The crosslinking of starch-PVA blends by epichlorohydrin was carried out in the presence of a plasticizer in situ. The obtained films were analyzed by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), dynamic mechanical and thermal analysis (DMTA), and X-ray photoelectron spectroscopy (XPS), and remarkable changes in thermal stability and glass-transition temperature have been observed on plasticizing and crosslinking in different concentrations. Different kinetic models such as Coats-Redfern, Broido, Friedman, and Chang were used to calculate the kinetic parameters of thermal decomposition. The results suggest that the thermal stability and activation energy of thermal decomposition passes through maxima at a critical concentration of plasticizer and increases with increasing crosslinker concentration. High-resolution C 1s XPS analysis was used to provide a method of differentiating the presence of various carbons associated with different environment in the films. (c) 2006 Wiley Periodicals, Inc.