Chemical conversion
mohammad najafianashrafi; Payam Moradpour; Ahmad Jahan latibari; Hamidreza Edalat
Abstract
Poly vinyl acetate (PVAC) adhesive is one of the most important adhesives in wood and furniture industry, which has many advantages such as low cost, environment friendliness and non-toxicity. However, it has some disadvantages such as low water resistance and poor boning strength. In this study, the ...
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Poly vinyl acetate (PVAC) adhesive is one of the most important adhesives in wood and furniture industry, which has many advantages such as low cost, environment friendliness and non-toxicity. However, it has some disadvantages such as low water resistance and poor boning strength. In this study, the effect of nano silica (NS) on the properties of poly vinyl acetate adhesive was investigated. The adhesive formulation with different NS contents (2, 3 and 4%) was added to the PVAC. The structure of the prepared adhesive samples was studied by FT-IR and XRD. We used the wood of Acer tree (Acer cappadocicum) to make joints in this study. Two standards of D882 and ASTM D905 were used for tensile and shear tests, respectively. Results showed that adding NS to PVAC enhanced the tensile strength of films. For example, the tensile strength of prepared films was increased by 30% after adding 4% of NS. Moreover, shear strength test showed that NS up to 3% can improve PVAC bond strength. Viscosity results showed that increasing the weight of NS up to 3% to PVAC glue lead to an increase following a decrease in the viscosity
Saman Ghahri; Antonio Pizzi; Reza Hajihassani
Abstract
Presently, because of the human health issues related to the formaldehyde gas emission initiated from traditional wood adhesives like urea formaldehyde, the bio-sbased adhesives has shown a good solution for preventing health hazards for human and the environment. To achieve an acceptable approach in ...
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Presently, because of the human health issues related to the formaldehyde gas emission initiated from traditional wood adhesives like urea formaldehyde, the bio-sbased adhesives has shown a good solution for preventing health hazards for human and the environment. To achieve an acceptable approach in wood based composites production, these adhesive need to qualify different standard limitations. This research was conducted to improve the bio-based soy-tannin adhesive for producing plywood with acceptable properties. For this goal, different adhesive formulations were prepared in the laboratory and they were treated at different temperature (40, 60, 80 ºC). Poplar wood plies with 2 mm nominal thickness were used to produce plywood specimens. The results showed the effectiveness of adhesives with heat pre-treatments at different temperature on shear strength (dry and wet) of plywood specimens. The highest shear strength of plywood specimens was achieved for 40 ºC treated adhesive in both dry and wet condition. Based on the results of shear strength test, all manufactured plywood specimens successfully met EN-314-2 standards requirement. Also, the results of delamination test revealed that plywood specimens which prepared by 40 ºC treated adhesive can successfully use for indoor condition, based on ANSI-HPV-1 requirements.
Composite wood products
Behzad Hosseini; mohammad ghofrani; Hamid Reza Taghiyari; Saman Ghahri
Abstract
In this research, Effect of soy flour addition into urea-formaldehyde resin on physical, mechanical properties and formaldehyde emission of plywood was investigated. Soy flour was mixed with urea-formaldehyde adhesive in three levels 5, 10 and 15% (based on dry weight of urea-formaldehyde adhesive) and ...
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In this research, Effect of soy flour addition into urea-formaldehyde resin on physical, mechanical properties and formaldehyde emission of plywood was investigated. Soy flour was mixed with urea-formaldehyde adhesive in three levels 5, 10 and 15% (based on dry weight of urea-formaldehyde adhesive) and three-layer plywood was manufacture from the resultant adhesive and poplar veneer. Properties of manufactured plywood including formaldehyde emission according to EN-717-3 standard, shear strength according to EN-314 standard and water absorption and thickness swelling according to EN-317 standard were investigated. The results indicated that addition of soy flour up to 15% decreased formaldehyde emission up to 29.34% and increased shear strength of panels. Moreover, delamination test (According to ANSI/HPV-HPV1 Standard) presented acceptable results. The results obtained from water absorption and thickness swelling after 2h and 24h showed that addition of soy flour increased the amount of water absorption and thickness swelling. thickness swelling after 2h and 24h showed that addition of soy flour increased the amount of water absorption and thickness swelling.
Physics and Mechanical Wood
Aysoda Talaei; Mohammad saleh Zare; Hamideh Abdolzadeh
Abstract
The aim of this study was to investigate the effects of furfurylation on shear strength of bond line and screw withdrawal resistance of beech (Fagus orientalis) and fir (Abies alba) species. In this regard, specimens with two different values of furfurylation i.e. low (fir 14% and beech 20%) and high ...
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The aim of this study was to investigate the effects of furfurylation on shear strength of bond line and screw withdrawal resistance of beech (Fagus orientalis) and fir (Abies alba) species. In this regard, specimens with two different values of furfurylation i.e. low (fir 14% and beech 20%) and high (fir 38% and beech 65%) levels were prepared and evaluated in comparison with untreated specimens. The furfurylation was performed after impregnating the specimens by furfuryl alcohol under vacuum condition followed by heating duration to complete polymerization and crosslinking. Specimens were prepared according to standard ASTM D 905 in order to assess shear strength of bond line formed with three different types of adhesives, single-component polyurethane, polyvinyl acetate as well as urea-formaldehyde. Also screw withdrawal resistance of wood polymer specimens was measured perpendicular to grain and parallel to grain. The results indicated that the shear strength of the bond line decreased and screw withdrawal resistance increased by furfurylation level. Examination of adhesion mechanism demonstrated that formation of an appropriate interface between water-soluble adhesives and wood-polymer involves effective penetration of adhesive into cell wall. Hence, the interface of adhesives and material would be the determining factor in developing strength of adhesive joints. Since the wood-furfuryl alcohol is a cell-wall wood-polymer, the possibility of creating an appropriate interface by increasing of furfurylation level was impaired. On the other hand, the adhesion mechanism of polyurethane glue compared to water-soluble adhesives such as polyvinyl acetate and urea-formaldehyde is significantly different, therefore exhibited more strength. The withdrawal screw resistance of furfurylated wood was increased by furfurylation level due to changing nature of wood and increasing shear strength of wood-polymer. This gain was also more evident in fir than beech. The results showed that screw withdrawal resistance perpendicular to grain was higher than parallel to grain.
Composite wood products
asghar tarmian; Kazem Doosthosseini; Seeyed Ahmad Mirshokraie; Mohammadmehdi Faezi poor
Abstract
Beneficial utilization of large quantity of paper sludge from Mazandaran Wood & Paper Industry in particleboard manufacturing has been studied. Single-layer and three-layer particleboard (paper sludge as a surface layer) were produced. Urea-formaldehyde resin at two levels of 10 and 12 percent and ...
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Beneficial utilization of large quantity of paper sludge from Mazandaran Wood & Paper Industry in particleboard manufacturing has been studied. Single-layer and three-layer particleboard (paper sludge as a surface layer) were produced. Urea-formaldehyde resin at two levels of 10 and 12 percent and paper sludge content at 4 levels, 0, 15, 30 and 45 percent were studied. Other factors such as press temperature (160oC), press time (6minutes), mat moisture (12%), board density (0.75g/cm3) and etc were constant factors. Mechanical and physical properties including bending strength, shear strength, thickness swelling and water absorption after 2 and 24 hours immersion were evaluated. The results indicated that application of paper sludge reduced mechanical properties and improved thickness swelling .The particleboard produced with 15%paper sludge had the least water absorption, but by using more paper sludge, water absorption increased. Single-layer particleboard had higher bending strength. However, there was no significant different in shear strength between single and three layer particleboard. Three-layer particleboard showed lower thickness swelling.
Composite wood products
Ahmad Jahan latibari; Habibalah Arabtabar; Fardad Golbabaei; Abolfazl Kargarfard; Amir Nourbakhsh; Abbas Fakhryan roghani
Abstract
Laminated beam ( LB.) and laminated veneer lumber ( LVL) manufactured from maple, hornbeam and beech wood is investigated. Three levels of press pressures at 30, 35, 40 kg/cm2, three levels of layer thicknesses of 2, 3, 4 mm and tangential and radial layers are investigated. Bending strength (MOR and ...
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Laminated beam ( LB.) and laminated veneer lumber ( LVL) manufactured from maple, hornbeam and beech wood is investigated. Three levels of press pressures at 30, 35, 40 kg/cm2, three levels of layer thicknesses of 2, 3, 4 mm and tangential and radial layers are investigated. Bending strength (MOR and MOE) and shear strength were measured according to ASTM 1186 and 905 respectively.The results of this investigation indicated that laminated wood strength of samples produced from hornbeam layers is superior to beech and beech is superior to maple. Statistical analysis of the results showed that the effect of wood species on strength properties is significantly different at 99% level. Press pressure also showed significant effect on strength. Increasing press pressure improved bending properties, but the highest shear strength was observed at 30 kg/cm2. Cutting direction did not influence bending strength and only influenced the shear strength. Even though the initial anticipation was the fact that thinner layer will produce stronger laminated wood. But the results or this study showed that layer thickness did not significantly affect strength properties.
