Kinetic evaluation of DSC curves for reacting systems with variable stoichiometric compositions

At present, the most popular programs for kinetic evaluation of reaction curves obtained by thermal analysis methods do not allow simultaneous analysis of systems with different stoichiometry. Consequently, valid predictions of the reaction behavior are limited to fixed compositions that have been investigated. Further, mechanistic conclusions should be taken with greatest caution if at all. The main aim of the new program is to determine the kinetic parameters for all (important) steps of an assumed and most probable reaction mechanism on the basis of differential scanning calorimetry (DSC) measurements and, of course, using these results to predict the reaction behavior for any complex temperature-time profile. Even if the reaction mechanism is not too complex, this can be done only if the experimental information is adequate. Therefore, besides having a sufficient reaction window (isothermal reaction temperatures and/or heating rates) the initial composition of the reaction mixture should also be varied as widely as possible. It is then possible to check the compatibility of the assumed reaction mechanism with the measured DSC curves. The new program was not developed to replace formal-kinetic evaluations but it is a valuable supplementary tool for kinetic evaluations. As a rule, results from other analytical methods must be considered in defining an adequate kinetic model, even if only the relevant elementary steps of the assumed mechanism are considered. The structure of the new evaluation program “Component kinetics” and a number of typical applications are discussed.