Comparison of activation energies obtained from modulated and conventionalnon-modulated TG

Recently, model free kinetic analysis of sinusoidal modulated TG-curves has been presented. In this contribution we compare the activation energies re sulting from model free analysis of modulated TG-curves and from Vyazovkin' s model free kinetic analysis of non-modulated TG-curves. We used polytetra fluorethylene and manganese oxide as samples. As a result we find, that bot h methods deliver similar activation energies for polytetrafluorethylene. H owever, the activation energies of manganese oxide deviate substantially. The main purpose of kinetic analysis is its potential for predictions of th e temporal behavior of materials under certain thermal conditions. Analysis of modulated TG-curves allows a model free determination of the temperatur e dependence of the activation energy. However, in order to make prediction s, one still has to rely on kinetic models such as e.g. first order kinetic s. This is in contrast to Vyazovkin's approach, which allows a model free d escription of kinetic processes in terms of a conversion dependent activati on energy. This function can then be used to make kinetic predictions witho ut any further assumptions with respect to reaction models. In this paper w e further discuss this fundamental difference.