Isothermal and non-isothermal kinetics of thermally stimulated reactions of solids

• Published in: International reviews in physical chemistry 1998-07, Vol.17 (3), p.407-433
• Main Authors: Vyazovkin, Sergey, Wight, Charles A.
• Format: Article
• Language: English
• ISSN: 0144-235X; 1366-591X
• DOI: 10.1080/014423598230108

This review covers both the history and present state of the kinetics of thermally stimulated reactions in solids. The traditional methodology of kinetic analysis, which is based on fitting data to reaction models, dates back to the very first isothermal studies. The model fitting approach suffers from an inability to determine the reaction model uniquely,and this does not allow reliable mechanistic conclusions to be drawn even from isothermal data. In non-isothermal kinetics, the use of the traditional methodology results in highly uncertain values of Arrhenius parameters that cannot be compared meaningfully with isothermal values. An alternative model-free methodology is based on the isoconversional method. The use of this model-free approach in both isothermal and non-isothermal kinetics helps to avoid the problems that originate from the ambiguous evaluation of the reaction model. The model-free methodology allows the dependence of the activation energy on the extent of conversion to be determined. This, in turn, permits reliable reaction rate predictions to be made and mechanistic conclusions to be drawn.