![]() ![]() The released acid works as a catalyst to facilitate the hydrolysis of hemicelluloses into oligomeric and monomeric structures. As wood is heated, acetic acid is formed by the hydrolysis of acetylated hemicelluloses. Most extractible compounds are formed by the alteration and degradation of hemicelluloses and lignin during thermal treatment. The extent of degradation depends on many factors, such as temperature, wood moisture content and processing time. ![]() reported that the wood densification process acts as a mild thermo-chemical pre-treatment which can impact biomass composition and structure.ĭuring wood densification, particularly at a high treatment temperature, the individual wood components undergo different chemical degradations. In recent years, many research efforts have been dedicated to using the appropriate densification process to improve wood properties. The main purpose of densification is to enhance wood density, which improves its mechanical performance and commercial value. The thermo-hygromechanical (THM) densification process involves the utilization of steam, heat and pressure to compress the wood structure. ![]() This species is widely used in the manufacture of furniture, flooring, farm tools, cutting blocks, fuelwood, veneer and other products. The sugar maple ( Acer saccharum Marsh.) is an important commercial hardwood in Canada, which has a relatively high hardness, dense grain and light color. Densification also facilitated the cleavage of the lignin side chains, resulting in increased phenyl units with short chains released during the pyrolysis process. The densification treatment favored the depolymerization of hemicelluloses and cellulose as indicated by an increased anhydrous sugar (levoglucosan) release during the pyrolysis process. The Py-GC/MS and XPS results show an increase of the oxygen/carbon atomic (O/C) ratio, which indicated that chemical substances containing oxygenated functionality were formed through the densification process. The results of the ATR-FTIR spectra confirmed the decomposition of hemicelluloses and the relative increase of cellulose and lignin contents on the wood surface. The obtained results suggest that the THM densification treatment resulted in significant chemical changes on the wood surface. The functional groups, surface chemical composition and internal structure and components of the control and densified samples were investigated using attenuated total reflection Fourier transform infrared (ATR-FTIR), X-ray photoelectron (XPS) spectroscopy and pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The THM densification process was performed at two different temperatures (180 ☌ and 200 ☌) with and without steam. The aim of this study was to investigate the effects of heat and steam on the chemical properties of thermo-hygromechanical (THM)-densified sugar maple wood. ![]()
0 Comments
Leave a Reply. |