Physics and Mechanical Wood
Mohammad Najafian ashrafi; Mohammad Ghorbanian Far; Esmail Rastbod; Mohammad Salehi; Mahdi Shamshiri
Abstract
The walnut tree is one of the most important species in Europe, Asia and Iran, which is used in various industries such as furniture, veneer, and construction due to its high resistance and beauty. In this research, walnut trees from two different geographic locations, one from the forests in the north ...
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The walnut tree is one of the most important species in Europe, Asia and Iran, which is used in various industries such as furniture, veneer, and construction due to its high resistance and beauty. In this research, walnut trees from two different geographic locations, one from the forests in the north of Iran (Noor) and the other in the west of Iran (Shahrkord), were selected. We studied physical properties including dry density, basic density, shrinkage, and mechanical properties including bending strength, modulus of elasticity, compression parallel to the grain, shear, tensile parallel and perpendicular to the grain, tangential and radial screw withdrawal strength and toughness. In this research, standards 3129 and ASTM D143-14 were used to perform physical and mechanical tests, respectively. The moisture content of all samples during mechanical tests was 12%. The average dry density of Noor and Shahrekord walnuts was 0.61 and 0.57 (g/cm3) respectively. The results of variance analysis showed that the characteristics and physical resistances of these two species were not significantly different except for dry density, radial, tangential and volumetric shrinkages. However, due to the higher density of Noor species, it showed higher mechanical resistance compared to the Shahrekord species.
Mohammad Ghofrani
Abstract
AbstractIn this study, alumina nanoparticles was added to clear varnishes (Sealer, clear, semi-polyester and polyurethane), and changes in adhesion strength on wood specimens of Walnut (Juglans Regia) and spruce (Picea Spp) were studied. The experimental samples were prepared from defect-free woods with ...
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AbstractIn this study, alumina nanoparticles was added to clear varnishes (Sealer, clear, semi-polyester and polyurethane), and changes in adhesion strength on wood specimens of Walnut (Juglans Regia) and spruce (Picea Spp) were studied. The experimental samples were prepared from defect-free woods with size of 300×100×10 mm and dried to 8 % moisture content in air drying and Killen drying, respectively. The samples surfaces finished and the clear varnishes applied on samples surfaces using pneumatic spry gun and the adhesion strength test was done on samples. The result of this study showed that the highest adhesion strength was observed in polyurethane varnishes with 6% alumina nanoparticles in walnut wood, and the lowest adhesion strength observed in cellulosic varnishes (sealer and clear) with 0% nanoparticles in spruce wood. It can be concluded that with the control of nano alumina percentage in varnishes in a defined level, the adhesion strength of the clear varnishes increased. Also, with improvement of varnishes’ adhesion strength on wood surface, the varnishes durability increased, consequently.
Mohammad Ghofrani; Samad Hoseinpour; Alireza Ashori
Abstract
In this study, the effect of silica nanoparticles and heat treatment of beech (Fagus orientalis),walnut (Juglans regia) and spruce (Picea abies) wood species on adhesion strength, drop contact angle and water absorption of clear coating lacquer were studied. For this purpose, samples with 8% moisture ...
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In this study, the effect of silica nanoparticles and heat treatment of beech (Fagus orientalis),walnut (Juglans regia) and spruce (Picea abies) wood species on adhesion strength, drop contact angle and water absorption of clear coating lacquer were studied. For this purpose, samples with 8% moisture and 200 × 100 × 20 mm were prepared. The wood samples were heat treated in oven at different temperatures of 160 and 180 °C for 3 hours. After finishing the treatment, the surface finish of the specimens was 120 and 180, respectively. Transparent lacquer folders containing 0, 0.5, 1 and 1.5% silica nanoparticles were used to cover the samples. The results showed that heat treatment increased the drop contact angle and the adhesion strength of the coating and increased the temperature of the drop contact angle treatment and the adhesion strength as well. Thermal treatment at 180 °C with coating containing 1% nano and lowest drop contact angle was observed in control samples. Wood samples treated with walnut at 160 ° C and containing 1% nano coating had the highest adhesion resistance. The water uptake of treated wood samples decreased compared to the untreated samples in all three species and this trend continued with the increase of nanoparticles in the coating so that the walnut control samples had the highest water uptake at 180 °C. and 1% nano coatings were the lowest water absorption in spruce.
Physics and Mechanical Wood
Hadi Dashti; Kambiz Pourtahmasi; asghar tarmian
Abstract
In this research, the effect of preheating in nitrogen medium on acoustic properties of walnut and white mulberry’s boards was studied. Sapwood boards of 300×20×20 mm with the green moisture content were prepared. Heat treatments were applied at 140 and 160 oC under pressure of 2 pascal ...
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In this research, the effect of preheating in nitrogen medium on acoustic properties of walnut and white mulberry’s boards was studied. Sapwood boards of 300×20×20 mm with the green moisture content were prepared. Heat treatments were applied at 140 and 160 oC under pressure of 2 pascal for 30 and 60 minutes. Following the heat treatment, the samples were dried in a convectional laboratory kiln of 8% at 50 oC, relative humidity of 50%, and air velocity of 1 m/s to the average final moisture content of 8%. Using the free vibration method on free- free bar, the dynamic modulus of elasticity and damping factor were evaluated. Results revealed that the heat-treatment at 140 oC for 30 minutes did not have a significant effect on vibration properties of the wood samples. On the other hand, the heat-treatment at 160 oC caused a significant increase in dynamic modulus of elasticity and also a reduction in the damping factor of walnut and white mulberry samples. The FTIR spectroscopy and X-ray studies showed that the degradation of cell-wall polymers and increase in the crystallinity of the walnut wood specimens occurred due to heat treatment at 160 0C.
Mechanical conversion of wood and wooden fittings
Mohammad Ghofrani; Hossein Hosseinkhani; Habib Rahimi dastjerdi; Saeid Khojasteh khosro; Parviz Amiri
Abstract
The objective of this study was to investigate the influence of hydrothermal treatment of walnut (Juglans regia) and caucasian elm (Zelkova Carpinifolia) wood species on their acoustic properties in radial and tangential directions. For this purpose, specimens were prepared with dimensions of 360 (L) ...
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The objective of this study was to investigate the influence of hydrothermal treatment of walnut (Juglans regia) and caucasian elm (Zelkova Carpinifolia) wood species on their acoustic properties in radial and tangential directions. For this purpose, specimens were prepared with dimensions of 360 (L) ×20 (R) ×20 (T) mm. Heat treatments in water medium were performed at 150ºC for 5 hours. Acoustic properties of specimens (specific modulus of elasticity, damping, acoustical coefficient, acoustical conversion efficiency and wave velocity) measured by free flexural vibration on a free-free bar method. Properties of treated specimens compared with control specimens. Result showed that hydrothermal treatment improved all acoustic properties of specimens. Acoustic properties of radial and tangential surfaces of walnut wood did not show significant difference; while in caucasian elm significant differences obtained between radial and tangential surface properties. Generally, better acoustic properties achieved in tangential direction of heat-treated Caucasian elm species. So, it is recommended as a suitable specimen to be used in making the sound-boards of musical instruments such as Iranian Santour and Xylophones and also resonator boxes.
Pulp and paper
Somayeh Solimani; Sayed javad Sepidehdam; Hamid Malkian
Abstract
The stability of colored paper through dyes is very important in manuscript restoration. In this project Japanese papers (model papers) were colored with different dyes such as henna, walnut and tea. Artificial aging test was performed on these papers as well. Dye effect on stability of colored papers ...
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The stability of colored paper through dyes is very important in manuscript restoration. In this project Japanese papers (model papers) were colored with different dyes such as henna, walnut and tea. Artificial aging test was performed on these papers as well. Dye effect on stability of colored papers was measured through mechanical (folding endurance, tensile breaking and tear resistance) tests before/after aging test statistically; folding endurance test results in color level is significant. Tea colored paper sample was not as stable as model paper in folding resistance and the average of tea sample compare to model sample was 39.9 to 69.5. Folding endurance reduction was seen in tea and henna samples following aging test. The effects on tensile and tear resistance were not statistically different or dyes were not affected to cause any increase or decrease in stabilities. Scanning electron microscopy (SEM) images of model and dyed papers have demonstrated color and aging effects. The pH test upon henna sample, have shown acidic condition. Model paper was not the same as dyed papers in terms of weight and thickness. All samples include model and dyed papers, demonstrated decrease in brightness and yellowness and increase in redness following aging test.
