Modelling of nonisothermal kinetics in thermogravimetry

A new, fast and simple numerical method is proposed for modelling data of t hermogravimetric analysis under arbitrary temperature-time relationships. T he algorithm searches for activation energies and rate constants by means o f minimisation of the average square of deviation, Delta, between computed and experimental curves on a scale of the logarithm of reduced time that, i n turn, is expressed as the integral of the Arrhenius exponential. The algo rithm tests phenomenological relations by considering the process mechanism . Eighteen known models corresponding to different physical and chemical pr ocesses are included as the basic set in the algorithm. Sequential analysis of the 18 variants and arrangement of values of Delta(1/2) in ascending or der allow a selection of the best of models. The less Delta(1/2) is, the ne arer is the calculated activation energy to the correct value. Then one can detect that satisfactory models provide a good approximation of the origin al kinetic curves.