Prerna P. Dhawade and Ramanand N. Jagtap
In differential scanning calorimetry (DSC), remnant moisture loss in samples often overlaps and distorts thermal events such as glass transitions. Temperature modulated DSC (TMDSC) is known for separating such overlapping processes. In this study, chitosan was depolymerized by oxidative degradation method. By this method, chitooligomers of different molecular weights were produced. The glass transition temperature (Tg) of chitosan and its oligomers was analyzed by temperature modulated DSC. While performing this event hermetically sealed pans were used. Tg of chitosan and its oligomers was resolved by TMDSC-exhibiting glass transition temperature in the first heating curve. The structural formation of chito-oligomers was evaluated by FTIR and 1H NMR. The water plasticizing effect on Tg of chitosan and its oligomers was discussed with the help of TMDSC measurements and the presence of water in them have been evaluated by FTIR and 1H NMR. XRD had explained the crystallinity of chitosan and its oligomers and even the effect of water on crystallinity.
