The determination of activation energy from linear heating rate experiments: a comparison of the accuracy of isoconversion methods
Starink, M.J. (2003) The determination of activation energy from linear heating rate experiments: a comparison of the accuracy of isoconversion methods. Thermochimica Acta, 404, 163-176. (doi:10.1016/S0040-6031(03)00144-8).
Model-free isoconversion methods are the most reliable methods for the calculation of activation energies of thermally activated reactions. A large number of these isoconversion methods have been proposed in the literature. A classification of these methods is proposed. Type A methods such as Friedman methods make no mathematical approximations, and Type B methods, such as the generalised Kissinger equation, apply a range of approximations for the temperature integral. The accuracy of these methods is investigated, by deriving expressions for the main sources of error which includes the inaccuracy in reaction rate measurement, approximations for the temperature integral and inaccuracies in determination of temperature for equivalent fraction transformed. Both highly inaccurate and highly accurate Type B methods are identified. In cases where some uncertainty over baselines of the thermal analysis data exists or where accuracy of determination of transformation rates is limited, type B methods will often be more accurate than type A methods.
|Additional Information:||The paper derives the method for calculation of activation energy from experiments at constant heating rate known as the Starink or Type B-1.92 method in which the key equation relates the heating rate, HR, the characteristic temperature, T, and the activation energy, E, through ln(HR/T^1.92) = -1.0008 E/RT + C . The method is recognized by the ICTAC kinetics committee as the most accurate in its group, and is widely used to analyse the activation energy of reactions in thermal analysis.|
|Keywords:||DSC, thermal analysis, linear heating, precipitation, modelling, thermal activation, polymers, metals, alloys, diffusion, calorimetry, reaction rate, Avrami, JMA, crystallisation, amorphous|
|Subjects:||Q Science > QC Physics
Q Science > QD Chemistry
T Technology > TA Engineering (General). Civil engineering (General)
T Technology > TN Mining engineering. Metallurgy
T Technology > TP Chemical technology
|Divisions:||University Structure - Pre August 2011 > School of Engineering Sciences
|Date Deposited:||08 Dec 2005|
|Last Modified:||30 Jan 2015 13:49|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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