Decomposition of solids accompanied by melting--Bawn kinetics.

The book "Chemistry of the Solid State", edited by W.E. Garner more than 50 years ago, contained a chapter (Chapter 10) by C.E.H. Bawn which dealt with the kinetics of the thermal decompositions of solids that are accompanied by some melting. Rate equations were derived and this model has become known as the Bawn model or as "Bawn kinetics". This kinetic model has proved particularly useful in pharmaceutical stability studies. The isothermal curves of extent of decomposition, alpha, against time for this model are sigmoidal and the problems of distinguishing this model from other sigmoidal models (Prout-Tompkins, Avrami-Erofeev) have been examined. Under programmed temperature conditions, distinguishability becomes even more difficult.