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

The thermal decomposition of solids is usually a multistep process. Th e traditionally applied thermal analysis methods do not measure actual concentrations but rather the extent of substance conversion as a fun ction of temperature. The kinetic processing of such experimental data by the overall method which assumes that the process is a one-step re action leads to incorrect values of the Arrhenius parameters and to fa lse isokinetic relationships. This can be avoided by using isoconversi onal methods to compute the effective Arrhenius parameters as a functi on of the extent of conversion. It was shown that the dependence both of the isokinetic temperature and of its confidence interval on the ex tent of conversion can be used to detect real isokinetic relationships for multistep processes. The procedure was tested on experimental dat a and the resulting isokinetic relationship was interpreted in terms o f the reaction mechanism. (C) 1995 Academic Press, Inc.