Thermal Decomposition Using TG–FTIR Coupled Analysis

Abstract

Thermal decomposition analysis is fundamental for evaluating the stability, degradation pathways, and safety profile of materials exposed to elevated temperatures. Thermogravimetric analysis (TG) provides quantitative information on mass loss, while Fourier-transform infrared spectroscopy (FTIR) identifies evolved gaseous products. The coupling of TG with FTIR (TG–FTIR) offers a comprehensive analytical platform capable of correlating weight-loss events with chemical species released during thermal degradation. This integrated technique has gained increasing importance in polymer science and pharmaceutical research. Selected polymeric and pharmaceutical samples were subjected to TG–FTIR analysis under a nitrogen atmosphere. Approximately 8–10 mg of each sample was heated from 25°C to 800°C at a constant heating rate of 10°C/min. The evolved gases were transferred through a heated interface to the FTIR gas cell to prevent condensation. TG and DTG curves were recorded and synchronized with FTIR spectra to identify volatile degradation products and correlate them with specific thermal events. Distinct multi-stage decomposition patterns were observed for all samples. Polymeric materials demonstrated higher onset degradation temperatures compared to pharmaceutical compounds. FTIR analysis revealed the evolution of CO₂, CO, H₂O, and volatile organic compounds at characteristic temperatures corresponding to dehydration, bond cleavage, and oxidative degradation phases. The integration of TG and FTIR data enabled accurate identification of decomposition pathways and estimation of kinetic parameters. TG–FTIR coupling provides a robust and informative technique for comprehensive thermal characterization. The method enhances mechanistic understanding of degradation behavior and supports the development of thermally stable materials in industrial and pharmaceutical applications.