Hot Compression of Calcium Chloride and Sodium Carbonate Modifies Wood for Tsoongiodendron odorum

Abstract

To enhance the density and properties of Tsoongiodendron odorum and expand its range of applications, the physical and mechanical characteristics, such as density and hardness, were investigated after impregnating a solution of sodium carbonate and calcium chloride to generate calcium carbonate filler within the wood, followed by thermal compression. The results showed that the surface density of wood was significantly increased by 86.4%. The rate of weight gain gradually increased with sodium carbonate concentration, reaching a maximum of 55.67%. Hardness increased by 85.3%. The optimal treatment process is a compression rate of 5%, a pressing temperature of 170 °C, and a hot-pressing time of 30 min. Microscopic observations revealed that the calcium carbonate was predominantly distributed on the surfaces of wood, while the surface cells exhibited deformation upon compression. Conversely, the cells in the innermost region of the wood remained largely unaltered, thereby achieving a stratified compression effect. Impregnation and compression treatment increases the hardness and bending strength of Tsoongiodendron odorum, but spring-back may occur, and the dimensional stability measures necessitate further investigation and analysis.