Impact of steaming on the chemical composition of maple wood

Abstract

Chemical changes resulting from the thermal treatment of maple wood (Acer platanoides L.) through various steaming techniques were evaluated. Main wood components were isolated and characterized from the maple wood samples after steaming. Then, the isolated holocellulose and dioxane lignin were analyzed using ATR-FTIR spectroscopy. The effects of an increase in temperature and extension of the steaming period were seen primarily in the holocellulose and extractives contents, and less in the cellulose and lignin components. Certain steaming methods resulted in an increase in chemical composition, while others saw a decrease. The cellulose content of steamed maple wood was not considerably altered; however, the cellulose crystallinity did increase. The slight changes observed in this study can be attributed to several concurrent effects. While the lignin content in steamed maple wood showed only minimal changes, there were several changes in the structure of the lignin macromolecule. Demethoxylation, the decrease in the ratio of syringyl-propane to guaiacyl-propane units, and the formation of new alpha-C=O bonds were also observed. The hydrothermal treatment of wood also resulted in color changes of wood samples; the intensity of the change depended on the intensity of the treatment.