Wood Temperature

Effect of temperature on the change of wood components can be described as follows: during drying in the interval 40°-90°C, some minor chemical changes probably start to occur, most likely certain extractives. For high temperature drying in the interval 90°-150°C, the changes for all wood components are more obvious. At temperatures of 150°-250°C, major changes in the wood components occur, both degradation and modification, and at temperatures above 250C carbonization processes generally occur with the formation of CO2 and other pyrolysis products. The heat treatment of wood changes it chemical composition by degrading cell wall compounds and extractives. The extractives in the wood degrade more easily, and these compounds evaporate from the wood during the heat treatment. The hemicelluloses are the first structural compounds to be thermally affected. Cellulose and lignin degrade more slowly and at higher temperatures than the hemicelluloses.
The change in wood structure and chemical components during heat treatment affected the properties of wood. Hidayat et al. (2014) revealed that heat treatment resulted in a darkening of wood and the color became dark with temperature increase. Their study also revealed that the effect of treatment temperature on color change in sapwood is more obvious than in heartwood. Hidayat et al., (2014) …show more content…
The resulting wood is more hydrophobic as Metsa-Kortelainen et al. (2006) reported that heat treatment of Scots pine and Norway spruce heartwood at temperatures 170°C, 190°C, 210°C, 230°C evidently decreased the water absorption of wood, with the higher the temperature, the lower the amount of absorbed moisture. Hakkoe et al. (2005) reported that at temperatures higher than 130°C, rearrangement of wood hydrophilic polymers and plasticization of lignin occurs, which limit both dimensional swelling and water