Kissinger kinetic analysis of data obtained under different heating schedules

Abstract

The dynamic heating rate method developed by TA Instruments ( Hi-Res ™ ) is a kind of sample controlled thermal analysis in which a linear relati onship between the logarith m of the heating rate and the rate of weight change is imposed. It is s hown in this paper that the reacted fraction at the maximum reaction rate strongly depends on the parameters selected for the Hi-Res heating algorithm, what invalidates the use of the Kissinger method for analysing Hi-Res data unless that the reaction fits a first order kinetic law. Only in this latter case, it has been demonstrated that it is not required that a constant value of the reacted fr action at the maximum reaction rate is fulfilled for determining the activation energy from the Kissi nger method. In such a case the Kissinger plot gives the real activation energy, independently of both the heating schedule used and the value of the reacted fraction, α m , at the maximum.