The Effect of ThermoWood Method Heat Treatment on Physical and Mechanical Properties of Sorbus torminalis

Heat treatment is a modification method that has gained importance since the 1990s as part of the trend for more rational use of wooden materials. Heat-treated wood products are becoming more popular and have an established place in the market. For this reason, it is important to research applications for various wood types after heat treatment. In this study, Sorbus torminalis panels were first heat treated by the ThermoWood® method. Then, some physical properties (i.e., oven-dry density, air-dry density, shrinkage, swelling, 24-h water thickness swelling, and water retention), and mechanical properties (i.e., parallel compressive strength to grain, bending strength, and modulus of elasticity in static bending) were examined in ThermoWood® Sorbus torminalis. The results indicated that the physical property values of the heat-treated samples were lower than those of the control samples. Reductions of 14.4%, 12.1%, 64.9%, 49.3%, and 51.7% were observed for the oven-dry density (ODD), air-dry density (ADD), water thickness swelling (WTS), shrinkage (β), and swelling (α), respectively. Among the mechanical properties, there was a reduction in the bending strength (MOR) value, while the compressive strength parallel to the grain (CS) value increased up to 23.6% compared to the control samples. In contrast, no significant weight changes or changes in the modulus of elasticity in static bending (MOE) were observed.