Conclusions
The effects of glycerol concentration (0%, 2.5%, 5% and 10%, w/ w) on the mechanical and thermal properties and molecular level interactions in starch–chitosan films were comprehensively stud- ied. It can be concluded that the antiplasticization effect was ob- served in starch–chitosan–glycerol films when the glycerol concentration was 2.5% (w/w). The antiplasticization was reflected in visible surface cracking in the SEM image and the high Tg value of 2.5% (w/w) glycerol film. At glycerol concentration of 5% (w/w) and above the starch–chitosan–glycerol films were typically plasti- cized by glycerol as evidenced from the significant (p < 0.05) de- crease in both tensile strength and Tg.
The addition of glycerol promoted the interactions among chitosan, starch and glycerol through hydrogen bonding. This was reflected as the main peaks located at 3328, 2927, 1638 cm