A comment on mathematical expressions used in solid state reaction kinetics studies by thermal analysis

Abstract

Computer calculations pertaining to the reaction kinetics analyses of simulated thermoanalytical data, generated under non-isothermal conditions, have been performed. Results obtained by using the two forms of the differential and integral equations descriptive of three different models of rate-controlled solid state reactions: phase boundary movement, nucleation-growth and three-dimensional diffusion, have been examined and compared. Calculations have also been performed to examine the correctness of employing the simple diffusion model equations to analyze data generated by taking into consideration differences in the density of reactant and product. For all models studied and compared, the activation energies are the same, but the pre-exponential factors differ slightly. They can be interconverted by the use of an appropriate multiplicative constant.