Forest Product Industry

Fast-growing tree species are important due to their short growth time before they are harvested. Both the Poplar and Eucalyptus species are fast-growing trees. These two species have been cultivated in many parts of the world, and they are used in several ways, including in the pulp and paper industry, as wood-based panels, and as structural composite lumber. In this study, laminated veneer lumbers were produced using different combinations of Poplar (Populus x euramericana I-214) and Eucalyptus (Eucalyptus grandis) veneers. Some physical and mechanical properties, including density, thickness swelling, water absorption, modulus of elasticity, modulus of rupture, impact bending, and bonding performance were investigated. According to the test data that were obtained, the mechanical properties of laminated veneer lumbers produced with Eucalyptus were greater than those of laminated veneer lumbers produced with Poplar. When the two were combined and Eucalyptus was used as the top and bottom plies, the mechanical properties also were better than those of Poplar laminated veneer lumbers. As a result, it can be said that both Poplar and Eucalyptus veneers can be used to produce laminated veneer lumbers, and Poplar laminated veneer lumbers can be reinforced with Eucalyptus veneers.

ÖZET Yüksek sıcaklıklardaki ısıl işlem uygulaması odunu modifiye eden yöntemlerden birisidir. Yöntem, nitrojen gazı, buhar ve bitkisel yağlar gibi farklı ortamlar kullanılarak uygulanmaktadır. Odunun fiziksel özelliklerinden bazıları ısıl işlem muamelesi ile değiştirilmektedir. İşlem görmüş odunun, daralma genişleme, denge rutubeti miktarı, genişleme ve daralma anizotropisi gibi fiziksel özellikleri azalmaktadır. Odunun boyutsal kararlılığı artmaktadır. Ayrıca, istenmeyen bir sonuç olarak, odunun mekanik özellikleri de azalmaktadır. Ancak, odunun biyolojik dayanıklılığı artmaktadır. En uygun ısıl işlem sıcaklığı, odunun kullanılacağı yere göre seçilmektedir. Bu çalışmada, çam odunu (Sarıçam), 160, 180, 200 ve 220 °C sıcaklıklarda ısıl işlem görmüş ve fiziksel özellikleri ve sertlik değerleri belirlenmiştir. Ayrıca, fiziksel özellikler ve sertlik değerleri arasındaki ilişki regrasyon analizi kullanılarak belirlenmiştir. Elde edilen bulgulara göre önemli bazı sonuçlar rapor edilmiştir. ABSTRACT Heat treatment at high temperatures is the one of the methods of modifying wood. The methods were applied using different media, such as nitrogen, steam, and vegetable oils. Some of the physical properties of the wood are altered by the heat-treatment process. The physical properties of treated wood are decreased, such as swelling and shrinkage, equilibrium moisture content, and swelling and shrinkage anisotropy. Dimensional stability of wood increases. In addition, the mechanical properties of the wood are decreased, which is an undesirable outcome. However, the biological durability of the wood increases. The most suitable heat-treatment temperature is chosen based on the areas where the wood will be used. In this study, pine wood (Pinus sylvestris L.) was heat treated at temperatures of 160, 180, 200 and 220 °C, and the physical properties, including the hardness of the wood, were determined. In addition, the relationship between the physical properties and hardness was determined using regression analysis. Some important results were reported based on the data that were obtained.

Modulus of elasticity of reinforced plywood increased significantly. Reinforcement decreased the inequality between parallel and perpendicular samples. Compared to control samples, moisture content decreased, and density increased. Thickness swelling and water absorption decreased for the test groups. a b s t r a c t The reinforcement of solid wood and wood-based composite materials is not a new idea, but there have been very few studies about reinforcing poplar plywood with glass fiber fabric using phenol formalde-hyde. In this study, plywood panels were produced using poplar veneer and phenol formaldehyde adhesive and glass fiber fabric. One control group and three different test groups were set up. In addition, perpendicular and parallel test samples for each group were set up for bending tests. Some of the physical and mechanical properties of the reinforced plywood were determined using various tests. The results of the testing indicated that the plywood that was reinforced with woven glass fiber had a significantly increased modulus of rapture and modulus of elasticity of perpendicular samples. It was determined that density of the plywood was increased in the test groups. Thickness swelling and water absorption decreased for the test groups in which the plywood samples had woven glass fibers bonded onto in their surfaces. In the bending tests, the reinforcement provided by the glass fiber fabric decreased the inequalities between the parallel and perpendicular samples.