Thermal degradation kinetics of chitosan–cobalt complex as studied by thermogravimetric analysis

The thermal degradation of chitosan–cobalt complex at different heating rates in nitrogen was studied by thermogravimetric analysis (TGA) in the temperature range 30–800 °C. Fourier transform-infrared (FTIR) and X-ray diffractogram (XRD) analyses were utilized to determine the micro-structure of chitosan–cobalt complex. The results indicate that the thermal degradation of chitosan–cobalt complex in nitrogen is a two-step reaction, characteristic temperatures and the maximum reaction rate of thermal degradation increase with the increment of heating rate. The kinetic parameters were determined by using Friedman and Flynn–Wall–Ozawa methods. Coats–Redfern method was used to discuss the probable degradation mechanism. The results show that activation energy of the complex resulting from two kinetic methods has similar variable tendency, and the solid-state decomposition in the first degradation stage, which is non-spontaneous, goes to a mechanism involving nucleation and growth, Avrami–Erofeev function (A4) with integral form [−ln(1 − α)]4.