HEAT-TREATMENT OF CHITOSAN FILMS

Chitosan films, prepared from aqueous solutions of chitosan in 1 % v/v acetic acid, were subjected to heat treatment in an oven at known temperatures for specific durations. The effect of heat treatment on the water resistance of the films was measured by the extent of swelling and dissolution of the films in aqueous media of different pH. The results were correlated to heat induced changes in the physical characteristics of the films. Heat treatment enhanced to a greater extent the water resistance of chitosan films in a medium of low pH than in one of high pH. The improved water resistance may be attributed to the formation of crosslinks and/or crystallites in the films. Both the temperature and duration of heat treatment influenced the degree of heat induced changes in the films.