Study on the thermal degradation kinetics and pyrolysis characteristics of chitosan-Zn complex

- Thermal degradation kinetics and pyrolysis characteristics of chitosan-Zn complex were studied.
- Kinetic triplets were estimated by FWO, KAS and Coats-Redfern methods.
- The decomposition of chitosan-Zn complex was easier and more thorough, compared with chitosan.

The thermal degradation kinetics and pyrolysis characteristics of a chitosan-Zn complex have been studied by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and pyrolysis gas-chromatography/mass spectrometry (Py-GC/MS). FTIR analysis showed that the absorptions associated with the O  H, N  H, C  O and C  C bonds shifted to lower frequencies and became much less intense at high temperatures. Furthermore, several new peaks appeared at 3049, 2332, 2202 and 600-900 cm−1 under these conditions. TGA experiments indicated that the thermal degradation of the chitosan-Zn complex occurred over two stages. The kinetic triplets of the second thermal degradation stage were estimated by Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and Coats-Redfern methods, and the most plausible kinetic model was F3([(1−α)−2−1]/2), i.e., a third-order reaction. The Py-GC/MS results indicated that the pyrolysis of the chitosan-Zn complex was very complicated, producing many volatile products, including carbon dioxide, acetic acid and nitrogen-containing aromatic heterocyclic compounds. Compared with chitosan, the decomposition of the chitosan-Zn complex was easier and more thorough.