THE APPLICATION OF ISOCONVERSIONAL METHODS FOR ANALYZING ISOKINETIC RELATIONSHIPS OCCURRING AT THERMAL DECOMPOSITION OF SOLIDS

摘要

The thermal decomposition of solids is usually a multistep process. The traditionally applied thermal analysis methods do not measure actual concentrations but rather the extent of substance conversion as a function of temperature. The kinetic processing of such experimental data by the overall method which assumes that the process is a one-step reaction leads to incorrect values of the Arrhenius parameters and to false isokinetic relationships. This can be avoided by using isoconversional methods to compute the effective Arrhenius parameters as a function of the extent of conversion. It was shown that the dependence both of the isokinetic temperature and of its confidence interval on the extent of conversion can be used to detect real isokinetic relationships for multistep processes. The procedure was tested on experimental data and the resulting isokinetic relationship was interpreted in terms of the reaction mechanism. (C) 1995 Academic Press, Inc. [References: 30]