Thermal dehydration and degradation kinetics of heptylidene chitosan

Abstract

The thermal dehydration and degradation of chitosan and heptylidene chitosan were studied by differential scanning calorimetry at four different heating rates: 5, 10, 15 and 20 K min−1. The activation energy values of thermal dehydration and degradation of chitosan and heptylidene chitosan were investigated using different isoconversional and maximum rate (peak) methods viz. Kissinger–Akahira–Sunose (KAS), Tang, Starink, Flynn–Wall–Ozawa (FWO) and Bosewell. The variations of activation energy, E α, with conversion function, α, established using these different methods were found to be similar. Compared to the FWO method, the KAS method offers a significant improvement in the accuracy of the E a values. All the maximum rate (peak) methods yielded consistent values of E α for the dehydration and degradation reactions of both chitosan and HEPT-chitosan. From the results, it can be concluded that one can follow the maximum rate (peak) methods to get the value of E α ; however, the complexity of the reaction can be identified only through isoconversional methods.