Phenomenological kinetics - An alternative approach

Traditional phenomenological kinetics describes the process rate in terms of the progress degree (mass fraction which has already undergone the change), alpha, and with a monomial function (or combination of monomial functions for multistep processes) of (1-alpha), without any connection to the underlying mechanism at the molecular level. The approach proposed in the present work aims at the direct treatment of the experimental data, like DSC records, without suggesting any specific reaction mechanism and excluding any Arrhenius like behaviour. Formal expressions are proposed that include the thermodynamic constraints for any spontaneous process, viz. a negative drop of the Gibbs function throughout the process, and describe the process rate as the result of the effects of a thermodynamic driving force, identified with the drop of the Gibbs function, and of the medium hindrance.