The effect of heat treatment on anatomical, physical, color and mechanical properties of birch wood

Since the information related to heat treatment of wood by industrial method is mainly related to coniferous wood, this research seeks to investigate the physical and mechanical properties of birch wood after heat treatment in the industrial furnace. For this purpose, birch wood according to the instructions of the Thermowood Association of Finland for the production of Class D Thermowood was used. Water absorption, dry and critical density and 12% Moisture, shrinkage, swelling, and color components (L*a*b*), anatomical features and wettability test, mechanical properties of wooden samples including MOE, MOR, impact strength and compression strength parallel to gain were evaluated and compared to the control samples. The results showed that the color of thermos-treated wood has become significantly darker than the control one. In birch wood, the moisture content of heat-treated wood showed a decrease of 117.7% compared with the control sample. The critical density of heat-treated wood showed an increase of 7.3% compared with the control sample. The dry density of the sample after heat treatment showed a decrease of 0.6% compared with the control sample. The density after heat treatment showed an increase of 2.3% compared with the control sample. The shrinkage and swelling of the thermos-treated sample showed a decrease of 100.5% and 115.4%, respectively, compared with the control sample. It was more difficult to prepare the section of the heat-treated wood than the control sample, while destruction of vessels, fibers, and rays was visible. The modulus of elasticity, modulus of rupture, impact strength and compression strength parallel to gain of the heat-treated samples showed a decrease of 3.22, 3.4, 147.97 and 2.95%, respectively, compared with the control sample.