Effects of thermal modification on the chemical structure of fast-growing woods

Thermal modification improves wood properties through heat treatment alone, eliminating the need for chemical additives and expanding the potential for sustainable applications. This study evaluated chemical changes in Cedrela sp., Eucalyptus sp., and Pinus sp. woods subjected to thermal modification at 140, 180, 220, and 240 °C, using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TG/DTG). Results indicated progressive reduction of hydroxyl groups with increasing temperature for all species, reflecting decreased hygroscopicity. Eucalyptus sp. showed greater sensitivity at lower temperatures (140 °C), while Pinus sp. exhibited superior thermal stability across all treatments, with maximum crystallinity variation of 4.78%. The crystallinity index generally decreased with modification intensity, being most pronounced in Eucalyptus sp. (73.61% to 66.42% at 240 °C). Thermogravimetric analyses confirmed increased resistance to moisture adsorption, particularly from 220 °C onwards. These findings support the optimization of thermal modification protocols for fast-growing wood species, positioning them as sustainable alternatives to high-value timber in applications requiring improved dimensional stability.