Browsing by Author "Akyildiz M.H."

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Effects of heat treatment on calabrian pine (Pinus brutia Ten.) wood
(2009-08-01) Ates S.; Akyildiz M.H.; Ozdemir H.
In this study, the effects of heat treatment on some physical, mechanical, chemical properties, and cellulose crystallinity of calabrian pine (Pinus brutia Ten.) were evaluated. Wood specimens were treated with heat under atmospheric pressure at three different temperatures (130, 180, and 230 °C) and two different time levels (2 and 8 h). Air-dry density (Dm), oven-dry density (D0), shrinkage (β), swelling (α), fiber saturation point (FSP), compression strength parallel to grain (σc//), bending strength (σb), modulus of elasticity (MOE) in bending, equilibrium moisture content (EMC), holocellulose, and alcohol solubility were decreased, whereas 1% NaOH solubility and lignin content were increased, depending on the heating temperature and time. Cellulose crystallinity of the samples was not changed significantly. 130 °C showed a minimal effect; on the other hand, 230 °C showed a maximum effect on all properties of the treated wood. That's why, for the heat treatment process, 130 °C for 2 h should be applied in situations where mechanical properties such as modulus of elasticity, compression strength, bending strength, and hardness are important. However, 230 °C for 2 h should be used in situations where it is preferred to obtain favorable physical properties, such as density, shrinkage, swelling, and moisture content.
Screw-nail withdrawal and bonding strength of paulownia (Paulownia tomentosa Steud.) wood
(2014-01-01) Akyildiz M.H.; Akyildiz, MH
The effects of screw type, moisture content, and grain direction on the screw and nail withdrawal strength and bonding strength were investigated for paulownia (Paulownia tomentosa Steud.) wood grown in Turkey. The withdrawal strength was carried out according to the ASTM-D 143 and ASTM-D 1761 and Turkish Standard 6094 in three directions (tangential, radial, and longitudinal) on 60 samples. The moisture content of half of the samples was 12 % and that of the other half 28 %.The experiment of bonding strength (BS EN 205) was applied to both sanded surfaces jointed by poly-vinly acetate and Desmodur-VTKA adhesives. Results of the tests indicate that, the withdrawal strength values at 12 % moisture content were higher than the 28 % for screws whereas the withdrawal strength for 28 % moisture content was higher than 12 % for nails. The maximum withdrawal strength value was found in the chipboard screw. In the case of directions, the withdrawal strength values of radial direction were found to be higher than the others for all parameters. The lowest withdrawal strength values were found in the longitudinal directions for both nails and screws. For adhesive types, the highest bonding strength of D-VTKA was found to be 5.64 N mm-2 and it was higher than the bonding strength with PVAc (5.33 N mm-2). However, there were no significant statistical differences between the two adhesive types. The results show that paulownia wood can be used for different purposes such as house construction, roof systems, and box cases as it possesses enough strength. © 2014 The Japan Wood Research Society.
Screw-nail withdrawal and bonding strength of paulownia (Paulownia tomentosa Steud.) wood
(2014-01-01) Akyildiz M.H.
The effects of screw type, moisture content, and grain direction on the screw and nail withdrawal strength and bonding strength were investigated for paulownia (Paulownia tomentosa Steud.) wood grown in Turkey. The withdrawal strength was carried out according to the ASTM-D 143 and ASTM-D 1761 and Turkish Standard 6094 in three directions (tangential, radial, and longitudinal) on 60 samples. The moisture content of half of the samples was 12 % and that of the other half 28 %.The experiment of bonding strength (BS EN 205) was applied to both sanded surfaces jointed by poly-vinly acetate and Desmodur-VTKA adhesives. Results of the tests indicate that, the withdrawal strength values at 12 % moisture content were higher than the 28 % for screws whereas the withdrawal strength for 28 % moisture content was higher than 12 % for nails. The maximum withdrawal strength value was found in the chipboard screw. In the case of directions, the withdrawal strength values of radial direction were found to be higher than the others for all parameters. The lowest withdrawal strength values were found in the longitudinal directions for both nails and screws. For adhesive types, the highest bonding strength of D-VTKA was found to be 5.64 N mm-2 and it was higher than the bonding strength with PVAc (5.33 N mm-2). However, there were no significant statistical differences between the two adhesive types. The results show that paulownia wood can be used for different purposes such as house construction, roof systems, and box cases as it possesses enough strength. © 2014 The Japan Wood Research Society.
Some technological properties and uses of paulownia (Paulownia tomentosa Steud.) wood
(2010-01-01) 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).
Technological and chemical properties of chestnut (Castanea sativa Mill.) wood after heat treatment
(2010-06-18) Ates S.; Akyildiz M.H.; Özdemir H.; Gümüşkaya E.
This study was performed to determine the effects of heat treatment on air-dry density (Dm), oven-dry density (D0), shrinkage (β), swelling (α), fiber saturation point (FSP), compression strength parallel to grain (σc//), bending strength (σb), modulus of elasticity (MOE) in bending, brinell-hardness (HB), equilibrium moisture content (EMC), chemical content and cellulose crystallinity of chestnut (Castanea sativa Mill.) wood. Wood samples were treated to heat at three different temperature (130, 180 and 230°C) and two different time level (2 and 8 h) under atmospheric pressure and presence of air. Dm, D0, β, α, FSP, EMC, σc//, σband MOE were decreased by heat treatment. Lignin content, 1% NaOH and alcohol solubility values increased with depend on the heating temperature and time. Cellulose crystallinity of the samples was not changed significantly. Consequently, for heat treatment process, 130°C for 2 h should be applied in place where mechanical properties are important. However, 230°C for 2 h should be used in place where preferred physical properties. Heat-treated chestnut woods could be utilized by using proper heat treatment techniques in outdoors and indoors applications for several purposes such as musical instruments, kitchen furniture, garden furniture and windows frames. © 2010 University of Bucharest.
Technological and chemical properties of heat-treated Anatolian black pine wood
(2009-06-03) Akyildiz M.H.; Ates S.; Özdemir H.
In this study the effect of heat treatment on air-dry density (D m), oven-dry density (D0), shrinkage (β), swelling (α), fiber saturation point (FSP), compression strength parallel to grain (σc//), bending strength (σb), modulus of elasticity (MOE) in bending, Brinell-hardness (HB), equilibrium moisture content (EMC), chemical content and cellulose crystallinity of Anatolian black pine [Pinus nigra J.F. Arnold subsp. nigra var. caramenica (Loudon) Rehder] was evaluated. Specimens were subjected to heat under atmospheric pressure at 3 different temperature (130, 180 and 230°C) and 2 different time levels (2 and 8 h). The value of Dm, D0, β, α, FSP, EMC, σc//, σb, MOE, holocellulose, 1% NaOH and alcohol solubility decreased, whereas, lignin content increased depending on the heating temperature and the time. Cellulose crystallinity of the specimens was not changed significantly. 130°C showed minimum effect, on the other hand, 230°C showed maximum effect on all properties of treated wood. Accordingly, for heat treatment process, 130°C for 2 h should be applied in place where mechanical properties are important. However, 230°C for 2 h should be used in place where a physical property is preferred. Consequently, heat treated Anatolian black pine woods could be utilized in applications for several purposes such as kitchen furniture, outdoor furniture and windows frames. © 2009 Academic Journals.
The impact of density and mixture ratio of melamine on some properties of oriented strand board
(2018-07-01) Akyildiz M.H.; Dogan K.; Kaymakci A.
The aim of this study is to determine the effects of density and melamine rate on thickness swelling, moisture resistance, modulus of elasticity in bending, bending strength and tensile strength of Oriented Strand Board. For this purpose, Oriented Strand Board panels were produced at three different density (550 - 570 - 590 kg.m-3 in size of 2440 x 1220 x 11 mm) and at five different mixture ratio of melamine in urea formaldehyde resin (0% - 2,5% - 5% - 15% - 20%). Urea formaldehyde and melamine urea formaldehyde included 65% solid content was used of 9,5% ratio relatively dry wood chip weight. At the process of Oriented Strand Board panels, Black pine (Pinus nigra), Scots pine (Pinus sylvestris) and Fir wood (Abies nordmanniana) chips were used at a rate of 80%, 15%, and 5%, respectively. Obtained results show that a linear correlation between the value of horizontal bending resistance, modulus of elasticity with panel density and melamine amount. It was understood that the values of longitudinal bending resistance did not show a direct increasing or decreasing in melamine amount and value of density. As it is seen that the values of longitudinal modulus of elasticity increases in proportion with the increase in the density. In perpendicular tensile strength to the surface; it is seen that values of all glue groups and density values which are intended by the standard for density values are covered. As melamine reinforcement ratio increases, average values of free formaldehyde decrease. It was determined that there was no direct correlation between the value of thickness swelling and panel density, and it had a correlation with used glue type.