Thermogravimetric analysis of chitosan

Abstract The thermal degradation of chitosan at different heating rates B in nitrogen was studied by thermogravimetric analysis. The results indicate that the thermal degradation of chitosan in nitrogen is a one‐step reaction. The degradation temperatures increase with B . Experimentally, the initial degradation temperature ( T 0 ) is (1.049 B + 326.8)°C; the temperature at the maximum degradation rate, that is, the peak temperature on a differential thermogravimetry curve ( T p ), is (1.291 B + 355.2)°C; and the final degradation temperature ( T f ) is (1.505 B + 369.7)°C. The degradation rates at T p and T f are not affected by B , and their average values are 50.17% and 72.16%, respectively, the maximum thermal degradation reaction rate, that is, the peak height on a differential thermogravimetry curve ( R p ), increases with B . The relationship between B and R p is R p = (1.20 B + 2.44)% min −1 . The thermal degradation kinetic parameters are calculated with the Ozawa–Flynn–Wall method. The reaction activation energy ( E ) and frequency factor ( A ) change with an increasing degree of decomposition, and the variable trends of the two kinetic parameters are similar. The values of E and A increase remarkably during the initial stage of the reaction, then keep relatively steady, and finally reach a peak during the last stage. The velocity constants of the thermal degradation vary with the degree of decomposition and increase with the reaction temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007