Thermogravimetric Analysis of Composite Phase-Change Materials

The paper explores the application of the Kolmogorov–Johnson–Mehl–Avrami (KJMA) equation with a temperature-dependent rate constant for analyzing thermogravimetric data of composite phase-change materials. Traditional methods, such as Ozawa–Flynn–Wall and Kissinger–Akahira–Sunose equations, require multiple heating rates, which is not always feasible. The study focuses on cellulose microfibrils, Trametes hirsuta mycelium, and cellulose/mycelium composites loaded with eicosane or stearic acid. The KJMA equation, modified with an Arrhenius term, is shown to effectively fit the TGA and DTGA curves, although further modifications are needed to accurately capture asymmetric DTGA peaks. The two-stage KJMA equation is introduced to handle multiple thermal processes, demonstrating promising results in reproducing the shapes of TGA and DTGA curves. This innovative approach offers a practical solution for thermogravimetric analysis under constrained conditions.