Effect of thermal treatment on the stability and structure of maize starch cast films

The use of maize starch as an alternative material for producing cast films is highly dependent on the treatment conditions in order to obtain a biopolymer with outstanding properties. Thermal treatment conditions were controlled in maize starch cast films as a preliminary step in the modification of polymer properties. The stability of the films was studied by thermogravimetry (TGA), swelling experiments and Fourier-transform infrared (FTIR) spectroscopy. FTIR analysis indicated a degradation mechanism based on elimination of water followed by depolymerization. The activation energy values obtained from TGA results of thermally treated films suggest the occurrence of marked changes in the polymer stability which is consistent with the swelling experiments and indicates the thermal treatment as a suitable method to enhance the lifetime of starch-based biopolymers.