Ahmet Can

Comparative biological resistance of differently thermal modified wood species against decay fungi, Reticulitermes grassei and Hylotrupes bajulus

Thermal modified wood has some advantages over natural wood, including decreased hygroscopicity, increased dimensional stability, and enhanced durability. In this study, European species of Scots pine (Pinus sylvestris), spruce (Picea orientalis), ash (Fraxinus spp.), and tropical species of tali (Erythrophleum ivorense), and iroko (Chlorophora excelsa) were thermally treated at 180 °C and 210 °C for 1,5 and 2 h, respectively. We evaluated the resistances of the untreated and thermally treated samples to decay induced by the white rot fungus, Trametes versicolor and two brown rot fungi, Coniophora puteana and Postia placenta. In addition, the samples were exposed to the termite Reticulitermes grassei and the longhorn beetle species Hylotrupes bajulus to evaluate their resistance to damage by the insects. During the heat treatment, the mass loss of the samples generally was between 9 and 14%. After the heat treatment, experiments were conducted to determine the effects of white and brown rot fungi on samples of Scots pine and tali, the effect of C. puteana on spruce, and the effects of C. puteana and P. placenta on ash and iroko. In all experiments, the mass loss due to damage from the various fungi was less than 1% for the samples that had been heat treated at 210 °C. The untreated and heat-treated tropical species exhibited higher durability with very low mass loss and 100% mortality of the insects when attacked by termites, whereas the other wood species had moderate attack. In addition, Hylotrupes bajulus exposure by two standart methods (EN 46 and 47) resulted in similar performances in most cases, although EN 47 treated samples at 210 °C showed improved durability for Scots pine (Pinus sylvestris) and spruce (Picea orientalis).

Dimensional stabilization of wood treated with tall oil dissolved in different solvents

Many water repellents, such as classic wood preservatives have the disadvantage of being harmful to the environment. Therefore, interest increased even eco-friendly, or of biodegradable material. Natural oils (tallow, linseed oil), appears to be capable of preventing the wood water uptake. However, the total amount of oil required to achieve a high penetration of the sapwood. The aim of this study was to investigate the water repellent efficiency of tall oil dissolved in different solvents. As solvents ethanol, methanol, acetone and tall oil water emulsions were used. Scots pine and Uludag fir sapwood samples were impregnated with tall oil formulations. For this purpose we used tall oil/solvents (W/W) at the concentrations of 10% and 20% respectively. Test samples cut into small sizes (20 x 20 x 10 ± 0,2 mm) for water uptake and tangential swelling tests. The tests were carried out based on American Wood Protection Association (AWPA) standard E4 (2003).

Mechanical, morphological and thermal properties of nano-boron nitride treated wood materials

Thermal instability is the one of the most important disadvantages of wood since it begins to decompose at a low temperature (˃110 °C). Many scientists, past and present, have conducted studies aimed at improving the thermal stability of wood. The aim of this study was to impregnate wood withnano-sized boron nitride (NBN) to improve its thermal stability and to investigate the changes in the properties of Scots pine (Pinus sylvestrist), Ash (Fraxinus exelsior), and Iroco (Chlorophora excelsa) woods after the impregnation. The effects of the impregnation with NBN also were investigated on theheat-treated woods. The impregnation was conducted with using full-cell method in a chamber under a pressure of 0.6 MPa for 1 h. Densities at 0% and 12% moisture content (MC), mechanical properties, color changes, thermal stability, and scanning electron microscopy (SEM/EDAX) analysis were determined. The test results showed that the impregnation of wood with NBN increased generally the flexural strength and elasticity of modulus at bending, but the NBN impregnation decreased generally the compression strength except for ACI, ATWI, IC, and ICI. It was also determined that the changesin density and color were statistically different after the impregnation. According to the SEM/EDAX results, deposits of nano-sized boron nitride were found inside the cell wall and on the pits. But the deposits were also determined in inside structure of the wood with EDAX analysis. Thermal stabilityin T10% and T50% of wood was found to improve after the impregnation with NBN. TG/DTG and DTA values for some samples were found to fluctuate due to the heterogeneous dispersion of the NBN in the wood.

Effect of weathering on wood treated with tall oil combined with some additives

Growing interest on bio-based material has led to focus on environmentally benign wood treatment systems because of the environmental concerns. Tall oil is a by-product from pulp and paper industry, contains resin and fatty acids, and is biodegradable. Tall oil treated wood can provide some reduction in water uptake and increase in decay resistance. In this research crude tall oil was dissolved in ethanol at 5, 10 and 15 % concentrations in the treatment of Scots pine according to full cell process. Dyestuff, iron oxide and sodium ascorbate were used an additive as 0,5 %. Weathering performance of tall oil and tall oil combined with additives were investigated in accelerated weathering chamber by application of ultraviolet irradiation and water spray. It is taken for granted that increasing concentration results in higher weight percent gain in treated samples. The best results were obtained with 10 % tall oil and iron oxide which indicated minimum total color changes. Colour measurements and visual examination revealed that iron oxide was the most effective additive in reducing weathering effect and lowering the total colour change.