Advanced Fitting Method for the Kinetic Analysis of Thermogravimetric Data

Abstract

The article considered the solution of the inverse problem of chemical kinetics of the analysis of experimental data of a thermogravimetric experiment at a constant sample heating rate. The fitting method for identifying the parameters of a kinetic triplet using the integral method for a model of a solid-state reaction based on the modified Arrhenius equation is described. The effectiveness of the proposed approach was confirmed by solving test cases for low, medium, and high rates of material conversion. Unlike other methods, setting the parameters of the reaction mechanism is not required, as they are determined by the solution. Solutions for real data of TGA studies with high and low sample heating rates were compared with the results obtained by other authors and experimental data. A description of the full cycle of calculations used to identify kinetic parameters from thermogravimetric experimental data is given, from the derivation of calculated relationships to the implementation of a short (three to five formulas) program code for MS Excel spreadsheets. The presented code is easy to verify and reproduce and can be modified to solve various problems.

Non-Isothermal Degradation Mechanism of Micro/Nano Titanium Dioxide-Enhanced Polycaprolactone Biocomposite

“…Further details on the thermal stability and characteristic degradation temperatures, such as the temperature at which 5% weight loss occurs (T 5% ), the temperature of the maximum degradation rate (T max ), and the final degradation temperature (T f ), of the investigated biocomposites can be found in our previous work [2]. Since thermogravimetry is recognized as a suitable and reliable method for monitoring the thermal degradation of polymeric materials [18][19][20], the results of non-isothermal thermogravimetry from our previous work [2] are used in this work for the kinetic analysis of PCL/TiO 2 biocomposites.…”

Improvement of the Mathematical Model for Quality Assurance in the Determination of Kinetic Parameters of Thermal Degradation of Polypropylene Through Thermogravimetric Analysis

“…[10][11][12][13][14][15][16][17][18] However, according to current literature, these approximations and associated approaches are less relevant than the specific problems of chemical kinetics; they are typically solved using computers, where the exact numerical calculation of the temperature integral can be easily incorporated into the algorithms. [19,20] In this work, a linear approximation in x and a reciprocal cubic polynomial approximation in x will be used, with errors of less than 0.4% for the linear approximation in the interval −50 ≤ x ≤ −21, and less than 0.032% for the polynomial approximation in the interval −200 ≤ x ≤ −15.…”

Thermal Degradation Studies of Poly(2-ethyl hexyl acrylate) in the Presence of Nematic Liquid Crystals

“…Thermogravimetric analysis (TGA) is commonly used to determine the thermal decomposition kinetics and thermal stability of polymers [13] and can be studied using single heating and multiple heating rate methods [14]. Model-free isoconversion methods [15,16] are the most reliable approaches for calculating activation energies of thermally activated reactions. A large number of isoconversion methods have been proposed, that allow the activation energy (E) of a process to be estimated as a function of the degree of conversion (α) [17].…”