In this study, influence of combined heat treatment and densification on mechanical properties of poplar wood (Populus usbekistanica) such as density, EMC, compression strength, modulus of elasticy, modulus of rupture and static bending strength were investigated. Poplar samples were subjected to a temperature of 120 o C, 160 o C and 200 o C for 1 and 3h. After the heat treatment, the heat treated samples were compressed in a hot press at a temperature of 120 o C, press pressure of 5 MPa and press time of 30 minutes for densification. The results showed that the heat treatment affected the densification with increasing density. Additionally, the heat treatment decreased modulus of rupture (MOR), modulus of elasticity (MOE) and impact bending strength (IBS) with increasing temperature for undensified poplar wood. In conclusion, densification process has improved all the mechanical tested properties.

One of the most important disadvantages of the wood material, whose usage is becoming more and more widespread, is the dimensional instability that occurs in its interaction with water. Therefore, studies to improve these drawbacks of wood, remain always up to date. For the mentioned purpose in this study, some chemical, morphological, physical and mechanical properties of Eucalyptus camaldulensis woods, which were naturally dried in outdoor and indoor climate in Eastern Mediterranean (Kahramanmaraş province) atmosphere conditions of Turkey, were investigated. According to the results of the study, chemical properties of Eucalyptus woods dried indoor were measured as merely 0,23 % higher than dried ones outdoor. The results of morphological measurements indicated that the fiber dimensions of eucalypt wood dried in indoor were average 1,48 % lower than the ones dried out outdoor. Also, as a result of statistical analysis, it was found that there were significant differences (ρ < 0,000) between the physical properties of Eucalyptus wood samples indoor and outdoor according to the t-test. At the same time, as a result of the t-test applied to determine the effect of drying conditions on mechanical properties of Eucalyptus wood, modulus of elasticity, compression, tensile, dynamic bending and shear strength did not cause any significant difference between indoor and outdoor, while bending and Janka hardness strengths showed significant differences at ρ < 0,000 level. Finally, when the data obtained as a whole is considered, it can be said that testing of Eucalyptus wood which requires a very sensitive drying in different climates has important contributions on the subject. Regarding eucalypts, which has a high distribution area (20 million hectares) in the world, it is recommended to relevant institutions and organizations to expand and maintain such study in the future. Lastly, according to obtained data from this study, it can be said that the experiments of Eucalyptus woods which require a very delicate drying in different environments provide important contributions on the subject.

Thyme oil, which is an anti-fungicide, was used to increase the physical and mechanical properties of wood as well as improve its strength, especially in outdoor conditions. For this purpose, Stone pine (Pinus pinea L.) wood samples classified according to the annual number of rings were exposed to either the impregnation process or the combined process, which was comprised of impregnation followed by heat treatment. As a result of the study, it was determined that the wood had different physical and mechanical properties based upon the number of annual rings. In addition, it was specified that the thyme oil used in the impregnation process improved the physical properties of the wood and also reduced the water absorption during the combined process. As a general conclusion, the impregnation process and the combined process increased the mechanical properties of the wood in parallel with an increase in the number of annual rings. The process of impregnation of wood materials with thyme oil is promising due to its anti-fungal and antibacterial properties, its ability to be used in small amounts in on-site impregnation, and it being an environmentally friendly product for the wood protection industry.

In this study, the effect of moisture content and density of panel on some physical and mechanical properties of fiberboard was investigated. The effect of moisture and density differences on some properties of fiberboard were aimed to be revealed. The test samples were obtained from fiberboards which were divided into three different density (0.590 g/cm 3 , 630 g/cm 3 and 0.680 g/cm 3 ) and moisture contents (6%, 9% and 12%) groups. Within the scope of the study, physical properties such as water absorption and thickness swelling and mechanical properties such as bending strength, modulus of elasticity, internal bond strength, Janka hardness and screw holding capacity were determined. The physical and mechanical properties of the boards with different moisture and density values differed significantly. For instance, the internal bond strengths were determined as 0.34 N/mm 2 , 0.39 N/mm 2 and 0.62 N/mm 2 in the low, medium and high density groups, respectively. Respective values for moisture content groups were found 0.52 N/mm 2 , 0.45 N/mm 2 and 0.38 N/mm 2 , respectively. Furthermore, the screw holding capacity which is important strength for fiberboard were determined as 15.3 N/mm 2 , 18.8 N/mm 2 and 25.3 N/mm 2 in the low, medium and high density groups, respectively. And respective values for moisture content groups were found as 19.8 N/mm 2 , 20.1 N/mm 2 and 19.4 N/mm 2 , respectively. In the samples belonging to the same moisture group, high mechanical properties at low moisture content and low mechanical properties at high moisture content were obtained. Research results revealed that the mechanical properties increased in parallel with the increase in density. Physical and mechanical properties of MDF boards change as the board density increases. Generally, as the board density increased, all mechanical properties increased. However, with the increase in moisture percentage, the mechanical properties of the boards decreased.

No abstract

Ağaç malzemenin kullanım alanlarında diri odun ve öz odun oranları, farklı özellikleri nedeni ile dikkate alınması gereken odun elamanlarındandır. Bu çalışmada Doğu Akdeniz Yöresinden alınan Okaliptüs (Eucalyptus grandis) ve Kavak (Populus usbekistanica) odunlarında diri odun ve öz odunlarının dinamik eğilme direnci (DED) değerleri araştırılmıştır. İlgili standartlara uygun olarak diri ve öz odun kısımlarından ayrı ayrı hazırlanan örneklerde dinamik eğilme (şok) direnci testleri şok test cihazında yapılmıştır. Yapılan testlerde elde edilen verilerin analiz edilmesi ile okaliptüs ve kavak diri ve öz odunlarının DED değerlerinin p<0.000 önem düzeyinde anlamlı farklılıklar oluşturduğu görülmüştür. Yine okaliptüs ve kavak diri ve öz odunlarının ayrı ayrı ağaç türlerine bağlı olarak hesaplanan DED değerleri üzerinde ağaç türünün signifikant olarak etki ettiği belirlenmiştir. Aynı zamanda, dinamik kalite değerleri (I D ) arasında da T-testi sonuçlarına göre signifikant farklılıklar oluştuğu tespit edilmiştir. Ağaç malzemede diri ve öz odun oranları kullanım yerine bağlı olarak dikkate alınsa da genel olarak öz odun oranı yüksek ağaç odunlarının daha değerli olduğu kabul edilmektedir.

In this article, it was aimed to demonstrate the values of water absorption and thickness swelling of samples prepared by adding beech fiber degraded by Lentinus edodes fungus to PVA (Polyvinyl Acetate) and PU (Polyurethane) adhesives, which are widely used in particle boards that one of the most important raw materials of the furniture industry. For this purpose, in the test samples produced, 150 g/m 2 was added to the adhesion surfaces for the control group, and 2.5%, 5% and 7.5% of degraded beech fiber was added to the glue for the other samples. In order to determine the hygroscopic properties of the particleboard test samples, water absorbing (WA) and thickness swelling (TS) tests were performed for 2, 24, 48, 72, 96 and 336 hours. As a result of the tests and statistical analysis, it was determined that the water absorption values of the samples treated with PVA were approximately 49% lower than those treated with PU. Also, thickness swelling percentages of the samples treated with PVA approximately 60% lower than those treated with PU. In addition to these, the addition of degraded beech fiber to the glue used did not statically have a significant effect on the results of water absorption and thickness swelling values in the samples treated with PVA, while it created significant differences in those treated with PU. However, it can be said that the fiber addition has a positive effect on the water absorbing and thickness swelling in both types of glue in the long-term (96 hours and above) treatment of test samples with water. According to the data obtained within the scope of the study, if the chipboards are combined with each other in open air conditions and humid environments, it may be recommended to prefer PVA glue with degraded beech fibers as an adhesive.

Ö z e t: Bu makalenin temel amacı, Dörtyol (Hatay) yöresinde doğal olarak yetişen Saplı meşe (Q. robur L.) odununun bazı mekanik özelliklerini belirlemek ve bu özellikler ile yörenin toprak yapısı arasındaki etkileşimi araştırmaktır. İlgili yörede belirlenen deneme alanlarından temin edilen materyal üzerin de yapılan mekanik testler sonucunda; liflere paralel basınç direnci 60.2 N/mm 2 , statik eğilme direnci 100.7 N/mm 2 , elastikiyet modülü 9939.8 N/mm 2 , dinamik eğilme direnci 1.4 kgm/cm 2 , makaslama direnci 16.6 N/mm 2 , liflere paralel çekme direnci 97.7 N/mm 2 , liflere dik çekme direnci 6.6 N/mm 2 , Janka sertlik (liflere paralel yönde) 98.9 N/mm 2 ve Janka sertlik (liflere dik yönde) 79.7 N/mm 2 olarak tespit edildi. Regresyon analizi, yoğunluk ile direncin pozitif ve kuvvetli artan bir ilişkiye sahip olduğunu, toprak analizleri ise, yetişme ortamının meşe için oldukça uygun olduğunu göstermiştir. Araştırmada elde edilen temel çıktılarla birlikte hesaplanan statik ve dinamik kalite değerlerinin katkısı ile de, meşe odununun orman ürünleri endüstrisinde diğer kullanım alanları ile birlikte kereste, doğrama, parke, lambri ve mobilya endüstrisinde de değerlendirilebileceği teyit edildi.