The impact of cupric ion on thermo‐oxidative degradation of chitosan

The thermal degradation of chitosan and chitosan–cupric ion compounds in air was studied using thermogravimetric and differential thermal analyses in the temperature range 30–600 °C. The impact of cupric ion on the thermo-oxidative degradation of chitosan was investigated. Fourier transform infrared and X-ray diffraction analyses were utilized to determine the microstructure of the chitosan–cupric ion compounds. Kinetic parameters such as activation energy, pre-exponential factor, Gibbs energy, and enthalpy and entropy of activation were determined using the Coats–Redfern equation. The results show that the thermo-oxidative degradation of chitosan and chitosan–cupric ion compounds is a two-stage reaction. The impact of cupric ion on the thermo-oxidative degradation of chitosan is significant, and all thermodynamic parameters indicate that the thermo-oxidative degradation of chitosan and chitosan–cupric ion compounds is a non-spontaneous process and proceeds via a mechanism involving nucleation and growth, with an Avrami–Erofeev function (A4) with the integral form [−ln(1 − α)]4. Copyright © 2010 Society of Chemical Industry