Gaussian model analysis and thermal decomposition kinetics of nature fibers

Abstract

The thermal decomposition of the heartwood and sapwood of eight wood species was investigated using dynamic thermogravimetric analysis in this study. To calculate the activation energy of the heartwood and sapwood, four “model-free” methods were used: the Flynn–Wall–Ozawa method, the modified Coats–Redfern method, the Friedman method, and the Kissinger method. Because the activation energy of the heartwood and sapwood was calculated using model-free methods that did not account for the reaction mechanism of the thermal decomposition of the hardwood and sapwood, the Gaussian multi-peak fitting method. The method did account for the reaction mechanism. The activation energy of the heartwood and sapwood was calculated using various methods in order to compare the results obtained by the various methods and, ultimately, to confirm the reliability of the results. The activation energy of the eight wood species' hardwood and sapwood ranged from 120 kJ/mol to 140 kJ/mol. The activation energy of the heartwood was slightly higher than that of the sapwood within the same wood species. Infrared spectrograms of the selected woods revealed that the heartwood had higher absorption peak intensities in the wavelength range of 3100–3500 cm −1 than the sapwood. This indicates that the heartwood, as opposed to the sapwood, requires more energy to sustain the chemical reaction at this stage. This is one of the primary reasons why heartwood has higher apparent activation energy values than sapwood. Furthermore, softwood had a higher activation energy than hardwood. Furthermore, when compared to other model-free methods, the Friedman method was less reliable for studying the kinetics of pyrolysis in the heartwood and sapwood of the eight wood species.