CORRELATION BETWEEN THE SHAPE OF A TG DTG CURVE AND THE FORM OF THE KINETIC MECHANISM WHICH IS APPLYING

A method of identifying the reaction mechanism in non-isothermal kinetics is presented based on the symmetry, width and height of the DTG curve. Using a computer program, which allows the calculation of a thermogravimetric curve from selected Arrhenius parameters, heating rate and reaction mechanism, it has been possible to study how these variables alter the shape of the DTG curves. It is shown that the value of alpha (fraction decomposed) at which the maximum rate is obtained is characteristic for any specific mechanism, and is altered only slightly by the magnitude of the Arrhenius parameters and the heating rate. As such, with complementary information based on the width of the DTG peaks, it is usually possible to identify the mathematical expression which describes the reaction.