Pyrolysis kinetics of bio-based polyurethane: Evaluating the kinetic parameters, thermodynamic parameters, and complementary product gas analysis using TG/FTIR and TG/GC-MS

In this study, the pyrolysis behavior and reaction kinetics of bio-based polyurethane (BPU) was investigated in comparison to the individual components enzymatic lignin (EL) and polyurethane (PU). The produced gas composition during their pyrolysis were investigated using thermogravimetric (TG) analysis combined with FTIR and TG coupled with TG-GC/MS. TG analysis indicated that the decomposition of BPU was comparable with that of PU. However, the larger peak temperatures in DTA curves and residue mass for BPU than that for PU indicated that the incorporation of EL improved its thermal resistance. Most of the absorbance bands in FTIR for both samples were similar, except of the absorbance at 1500-1750 cm⁻¹ for PU and 1000-1150 cm⁻¹ for BPU. The dominant evolved products were N-containing compounds for PU and BPU, however, the phenols and furans were detected during BPU pyrolysis. Based on the Flynn-Wall-Ozawa model, the average activation energy was determined as 176.1 kJ mol⁻¹ for BPU, which was larger than 159.5 kJ mol⁻¹ for PU and smaller than that of 298.5 kJ mol⁻¹ for EL. For PU and BPU, the experimental curves were comparable with F1.5 model at the conversion rate in the α range of 0.1–0.5 and F3 model beyond that range.