Effect of tall oil and heat treatment on the properties of wood material

Wood material has been used for centuries and is of great attention nowadays. Wood is used both indoor and outdoor for construction material and decorative purposes. However, it has been necessary to prolong the service life of wooden material due to the limitation of forest resources and increasing demand of wood. Environmental concerns and limitations on wood preservatives have been grown because of the heavy metal content of traditional preservatives. For this reason, environmentally friendly methods and using of nonbiocidals like vegetable oils have become important. One of these methods, heat treatment can improve the biological and physical properties of wood material. But, heat treatment reduce the mechanical properties of wood. The aim of this study is to eliminate this drawback by combination of tall oil and heat treatment. In this study, tall oil dissolved in ethanol at 10 % and 20 % concentrations respectively. Fir and poplar samples treated with tall oil solutions under 650 mmHg vacuum for 30 min and 6 bar pressure for 1 h followed by heat treatment at 180 and 200 °C for 1 and 2 h. Decay test, dimensional stabilization and mechanical tests such as bending and compression strength were performed on untreated and treated samples. Results indicate that the lowest water uptake was obtained with the formulations as follow; tall oil treatment, tall oil and heat treatment. Tall oil treatment at 20 % followed by heat treatment at 200 ºC was found to be the most effective. Generally, the combination of tall oil and heat treatment improved the mechanical properties like bending and compression strength and modulus elasticity. When the tall oil concentration increased from 10 % to 20 %, decay resistance was also increased, but the obtained results were found over 3 % mentioned in the test standard. Therefore, the formulations performed in the study were not resistant to decay fungi.