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Öğe Adhesive bond performance of heat-treated wood at various conditions(Triveni Enterprises, 2016) Kol, H.S.; Özbay, G.Heat treatment of wood leads to chemical, structural and physical changes in wood constituents, which can significantly affect the bonding performance of wood in several ways depending on the adhesive type used. In the present study, fir (Abies bornmülleriana Mattf.) and beech (Fagus orientalis L.) were heat treated at 170°C, 180°C, 190°C, 200 and 212°C for 2 hours. Four different types of adhesives were used for bonding process: melamine-urea-formaldehyde (MUF), melamine formaldehyde (MF), phenol formaldehyde (PF), and polyurethane (PUR). For all the pretreatment conditions, highest shear strength of adhesive bonds of each adhesive system was observed for untreated samples and shear strength decreased with increasing heat treatment. The strength of each adhesive bond of samples which were soaked in water was much less than dry samples, approximately half of the dry strength. Generally, the shear strength of the adhesive bonds after boiling was smaller than or similar to the values obtained for soaking. The untreated samples lost more strength after soaking and boiling than heat treated samples. With increasing heat treatment severity, reduction in shear strength increased in dry samples while decreased in soaking and boiling samples. For instance, after soaking, the untreated samples lost more strength (almost 39%) than heat treated samples (almost 24% for most severely heat treated samples). The results showed that the shear strength of adhesive bonds was influenced by heat treatment and depended on pretreatment of samples prior to testing. In general, all adhesives used performed in quite a similar way for all pretreatment conditions, and the bonding performance of heat treated fir wood was less satisfactory than that of beech wood for all adhesive system and condition. © Triveni Enterprises.Öğe Effects of some impregnation chemicals on combustion characteristics of laminated veneer lumber (LVL) produced with oak and poplar veneers(2010) Kol, H.S.; Ozbay, G.; Köse, L.; Kurt, S.The objective of this research was to investigate the effects of impregnation chemicals on the combustion properties of 3-ply laminated veneer lumber (LVL) made of Oak (Quercus petraea subsp. İberica) and Poplar (Populus tremula L.). For this purpose, oak wood was used as the outer ply and poplar used for the core ply in LVL. Borax (BX), boric acid (BA), borax+boric acid (BX+BA), and di-ammonium phosphate (DAP) were used as impregnation chemicals, and urea formaldehyde (UF), phenol formaldehyde (PF), and melamine-urea-formaldehyde (MUF) adhesives as bonding agent were used to produce LVLs. The vacuum-pressure method was used for the impregnation process. The combustion test was performed according to the procedure defined in the ASTM-E 69 standards, and during the test the mass reduction, temperature, and released gas (CO, O2) were determined for each 30 seconds. As a result, di-ammonium phosphate was found to be the most successful fire retardant chemical in LVL with MUF adhesive. LVL produced from a combination of oak and poplar veneers with MUF adhesive and impregnated with DAP can be recommended to be used as a fire resistant building material where required.Öğe Predicting Wood Strength using Dielectric Parameters(North Carolina State University, 2015) Kol, H.S.; Yalçin, I.There are various methods for nondestructive imaging of the internal structure of wood. A microwave nondestructive method based on the dielectric properties of a medium is an area of great interest for predicting wood strength in the worldwide wood industry, but the reliable prediction of strength in wood still has not been solved in a satisfying manner. Hence, answering the question of how dielectric properties of the wood are related to strength may improve the efficiency of models for predicting structural performance of wood by microwaves. Relationships were evaluated in this work between dielectric parameters (dielectric constant, loss factor, and loss tangent) and the strength properties of wood. Samples were prepared from fir and oak wood. Dielectric measurement was performed at a frequency of 9.8 GHz using Von Hippel’s Transmission Line Method. Wood density and some mechanical properties were then determined according to related ISO standards. The results showed that there were good relationships between the dielectric parameters and the MOR, MOE, IBS, and CS, especially for oak wood. The dielectric parameters were promising to predict wood strength with a high accuracy for oak but not fir, and the dielectric constant had a higher precision degree than the loss tangent and loss factor. © **Öğe Shear strength of heat-treated tali (Erythrophleum ivorense) and iroko (Chlorophora excelsa) woods, bonded with various adhesives(2009) Kol, H.S.; Özbay, G.; Altun, S.The aim of this study was to evaluate the effect of heat treatment on the shear strength of tali (Erythrophleum ivorense) and iroko (Chlorophora excelsa) woods, bonded with some structural adhesives. Shear strength of untreated and heat-treated woods bonded with phenol-formaldehyde (PF), melamine-urea-formaldehyde (MUF), melamine-formaldehyde (MF), and polyurethane (PUR) adhesives was studied. An industrial heat treatment method (ThermoWood) was used. The timbers were thermally modified for 2 hours at 180 °C. Laminated samples having two sample sets were prepared from untreated and heat-treated wood for the shear strength test. The results of the tests showed that the heat treatment affected shear strength of laminated wood negatively. Although there was a considerable difference in adhesive bond shear strength between untreated and treated wood, both wood species bonded with the adhesives fulfilled the required value for shear strength of the adhesive bonds. PF, MUF, MF, and PUR adhesives performed in a rather similar way for both wood species.Öğe Some technological properties and uses of paulownia (Paulownia tomentosa Steud.) wood(Triveni Enterprises, 2010) Akyildiz, M.H.; Kol, H.S.The aim of this study is to determine some physical and mechanical properties of Paulownia tomentosa wood grown in Turkey The samples trees harvested from Kargi in Corum. Physical properties including air-dry density, oven-dry density, basic density, swelling, shrinkage and oven-dry and air-dry thermal conductivity coefficients; mechanical properties including bending strength, modulus of elasticity in bending, compression strength parallel to grain, hardness, bonding strength were analyzed. Paulownia tomentosa wood's air dry and oven dry densities were determined as 0.317 and 0.294 g cm-3; basic density was determined as 0.272 g cm-3; volumetric shrinkage and swelling were determined as 7.78 and 8.41 %; tangential, radial and longitudinal air-dry thermal conductivity coefficients were determined as 0.089, 0.090 and 0.133 kcal/mh°C, respectively. Fiber saturation point (FSP) was found 28.79%; bending strength, Modulus of elasticity in bending, compression strength parallel to grain and Brinell hardness values (parallel and perpendicular to grain) were determined as 43.56N mm-2, 4281.32 N mm-2,25.55 N mm-2, 2.01 kgf mm-2 and 0.88 kgf mm-2, respectively. Consequently, paulownia wood can be widely used for various purposes such as house construction, furniture making, pulp and paper and handicrafts. © Triveni Enterprises, Lucknow (India).Öğe Thermal and dielectric properties of pine wood in the transverse direction(2009) Kol, H.S.In this paper, the thermal conductivity and dielectric parameters for pine [Pinus sylvestris (L.)] woods were determined in transverse directions for moisture conditions from oven-dry to 22 percent at a room temperature of 22 to 24 °C. Results indicate that the behaviors of thermal conductivity and dielectric parameters with moisture content and structural directions were similar. In general, the properties increased within the range studied with increasing moisture content. The radial values were similar to tangential values for both thermal conductivity and dielectric properties. The data presented here should be useful in most design problems where pine wood is subjected to microwave electric fields and heat changes.Öğe The transverse thermal conductivity coefficients of some hardwood species grown in Turkey(Forest Products Society, 2009) Kol, H.S.Thermal conductivity values for ash, oak, silver wattle, poplar, and beech were measured. Thermal conductivity coefficients of the wood species were determined for radial and tangential directions at four different moisture conditions, ranging from 0 to 22 percent moisture content (MC). Equations predicting thermal conductivities of the wood species according to the MC are proposed in the tangential and radial directions. The thermal conductivity test was performed with a quick thermal conductivity meter based on the ASTM C1113-99 hot-wire method, and measurements were carried out at a room temperature of 20°C to 24°C. The effect of density and porosity on thermal conductivity was also investigated. Results showed the behavior of all wood species studied is quantitatively similar. Thermal conductivity increased with increasing MC. Tangential thermal conductivity values within the MC range of 0 to 22 percent changed from 0.089 to 0.147 W/m-K for poplar, 0.127 to 0.222 W/m-K for beech, 0.113 to 0.202 W/m-K for ash, 0.142 to 0.290 W/m-K for silver wattle, and 0.130 to 0.219 W/m-K for oak. Tangential thermal conductivity was similar to radial thermal conductivity. Radial thermal conductivity was 1.08 times tangential thermal conductivity for poplar, 1.01 times for beech, 1.06 times for ash, 0.95 times for silver wattle, and 1.03 times for oak, respectively. The data are useful when calculating the energy required to kiln-dry lumber and predicting the thermal insulating qualities of log homes made from the species. © 2009 Forest Products Society.
