Determination of thermokinetic parameters and thermodynamic functions from thermoforming of LiMnPO4

Abstract

This article presents the determination of thermokinetic parameters and thermodynamic functions from the thermoforming of LiMnPO4. In our previous paper, a couple of thermoreaction processes, e.g., co-elimination and polycondensation of thermokinetics and thermodynamics, were incompletely determined. The co-elimination process is considered as dehydration and a deammoniation process in this paper. Evidently, an alternative technique was applied for calculating the extent of conversion values using the ratio of the peak area of the deconvoluted DTG peak after applying the Fraser–Suzuki deconvolution. An iterative equation of the integral isoconversional technique was used to estimate the reliable activation energy Eα. Each separated peak, including dehydration, deammoniation, and polycondensation, was obviously evaluated as a single kinetic process with its own kinetic parameters. In order to choose reliable mechanisms, the y(α) master plots or the plots between the experiment and the model were compared. The plots thus obtained showed that the dehydration, deammoniation, and polycondensation processes were found to be 3/2-order chemical reaction (F3/2), 2-order chemical reaction (F2), and nucleation (P3/2) mechanisms, respectively. The pre-exponential factor values were obtained from Eα, and the reaction mechanisms were found to be 3.78 × 1012, 7.05 × 1012, and 1.96 × 1013 s−1, respectively. The evaluated thermodynamic data of the activated complexes showed that the thermal reaction required thermal energy to complete the reaction.