Role of isoconversional methods in varying activation energies of solid-state kinetics

The concept of variable activation energy in solid-state reaction kinetics has caused considerable debate. Activation energy variation has been detected by isoconversional or “model-free” calculation methods, which generate activation energy as a function of reaction progress. The relationship between calculation methods and artifactual variation in activation energy was investigated in this work by employing model-fitting and isoconversional methods to analyze both simulated and experimental nonisothermal data. The experimental data was for nonisothermal sulfameter-dioxolane solvate desolvation by TGA. We show that variable activation energy in simple reactions could be an artifact resulting from the incorrect application of isoconversional methods.