Chemical, Crystallinity and Morphological Changes of Rubberwood (Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg.) Hydrothermally Treated in Different Buffered Media

Abstract

Hydrothermal treatment is an efficient and environmentally friendly method of enhancing the dimensional stability and durability of wood. The destructive effects of formic and acetic acids generated during thermal treatment, on the other hand, are known to have a negative impact on wood strength. As a result, hydrothermal treatment in different buffered media (acidic, neutral, and alkaline buffer) was performed in this study to mitigate the effects of the acids. As heating media, acidic buffer (pH 4 and 6), alkaline buffer (pH 8 and 10), and tap water (pH 7.43) were used to treat rubberwood at three different temperatures (160 °C, 180 °C, and 200 °C). The effects of different buffered media and treatment temperatures on the chemical components, crystallinity, and morphological changes in treated and untreated rubberwood were studied. The results of the experiments revealed that the chemical constituents of rubberwood changed along with the pH of the buffered media and treatment temperature. Rubberwood treated in alkaline media showed the least degradation, whereas water medium caused the most severe degradation. The crystallinity of wood increased initially (from 160 to 180 °C) and then decreased further at 200 °C. In addition, minimal damage to the wood cell was observed in an alkaline medium.