Accelerating thermal decomposition of wood cell wall with glycerol

Abstract Thermal modification reduces the hygroscopicity of timber potentially reducing susceptibility to biological degradation, but it is also energetically intensive. Identifying methods for accelerating the process could reduce these inputs. The potential effects of glycerol pretreatment on thermal modification was investigated by pre-treating poplar wood (Populus tomentosa Carr.) with 60% glycerol followed by thermal modification at temperatures between 120 and 200 °C for 4 h. Potential changes in the wood were analyzed using high performance liquid chromatography, infrared spectroscopy, X-ray diffraction, scanning electron microscopy and fluorescence microscopy to detect the changes in cell wall components, crystallinity, the average size of the crystalline region and cell wall thickness. Glycerol accelerated lignin decomposition over the entire temperature range. Thermal modification altered the degree of cellulose crystallinity as well as the average size of the crystalline region and the effects were more noticeable with the glycerol pre-treatment. The cell wall thickness of thermally treated wood decreased with increasing temperature and glycerol accelerated this process. Glycerol appears to enhance the modification process with increasing treatment temperature.