Following Maciejewsky and Vyazovkin?s explanation ‘‘this happens because in a single non-isothermal experiment both the temperature, T and extent of conversion, a vary simultaneously, and the approach generally fails to achieve separation of the reaction rate into the temperature dependence k?T? and the reaction model f?a?. As a result almost any f?a? can sat isfactorily fit data at the cost of drastic variations in the Arrhenius parameters, which compensate for the difference between the assumed form of the f?a? and the true but unknown reaction model’’.