FEATURES OF THE WATER ABSORPTION PROCESS OF THERMALLY MODIFIED WOOD

Abstract

The paper analyzes the process of thermal modification of wood obtained by a controlled pyrolysis process of heating wood (> 180 °C), which causes some chemical changes in the structures of cell wall components (lignin, cellulose, and hemicellulose) in order to increase its durability. It has been proven that the thermal modification process causes the breakdown of hemicelluloses and the amorphous part of cellulose, reduces water absorption, and reduces the amount of substances that are a breeding ground for fungi. In addition, lignin and the resulting pseudolignin undergo polymerization and redistribution throughout the cell volume, giving the cell walls greater density, hardness, and increased hydrophobicity (water repulsion), thereby reducing their ability to absorb moisture and swell. The polymerized lignin fills the internal cavity of the cell, forming a closed porous structure with a low ability to bind water. It has been established that the most effective parameter for reducing such substances is temperature and exposure time. The results of water absorption are presented, and a dependence is determined on the basis of which the diffusion coefficient for water absorption is calculated. During the thermal modification of wood for 6 hours, water absorption decreases by more than 10 times, which makes it possible to use it in objects with high humidity.