Composite wood products
Reza Jazayeri; Saeed Kazemi Najafi; Habibollah Younesi
Abstract
This study aimet at to use modified graphite materials as a multifunction additive in the UF resin for improving the properties of medium density fiberboard (MDF). For this purpose expanded graphite EG was synthesized from graphite using the Tsai et al (2011) method. Then, as-synthesized EG was intercalated ...
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This study aimet at to use modified graphite materials as a multifunction additive in the UF resin for improving the properties of medium density fiberboard (MDF). For this purpose expanded graphite EG was synthesized from graphite using the Tsai et al (2011) method. Then, as-synthesized EG was intercalated with manganese dioxide by Schwarz et al (1995) method and converted to MnO2-EG. Any additive was added to the urea formaldehyde resin in three doses of 1, 2 and 3% to make the relevant MDF panels with 750 kg/m3 nominal density. During the pressing time, the tT100oc parameter (time to reach temperature100○C) of the middle layer of the board under the influence of the additive was determined by a chromium-nickel-based thermocouple. The treatment of MnO2-EG3 (amount of 3% modified expanded graphite) showed the greatest effect in reducing tT100°C of the middle layer of the board by 22%. In addition, the elastic modulus increased by 68% as a result of this treatment. In addition, the elastic modulus increased by 68% as a result of this treatment. G and EG additives showed a higher degree of internal adhesion than that of MnO2-EG additive. In this regard, EG2 and EG3 treatments showed a 42% increase in internal adhesion and G2 treatment showed a 40% increase in internal adhesion. The effect of EG2 treatment in improving SW24 was greater than other treatments, so that it caused a 19% decrease compared to the control.
Reza Jazayeri; saeed kazemi najafi; Habibollah Younesi; Abolfazl Kargarfard
Abstract
In this study, the effect of graphite and two modified graphite materials in reducing formaldehyde emission of medium density fiberboard (MDF) was investigated. For this purpose, expanded graphite (EG) was syntesyzed from graphite (G) and modified expanded graphite (MnO2-EG) was produced through the ...
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In this study, the effect of graphite and two modified graphite materials in reducing formaldehyde emission of medium density fiberboard (MDF) was investigated. For this purpose, expanded graphite (EG) was syntesyzed from graphite (G) and modified expanded graphite (MnO2-EG) was produced through the intercalation process of expanded graphite with manganese dioxide. Thus, three graphite materials were prepared for resin treatment. Molecular tests including X-ray diffraction (XRD) and X-ray diffraction spectroscopy (SEM-EDS) were performed to determine their molecular properties,. In addition, the differential scanning caliber test (DSC) test was performed to evaluate the thermal behavior of the resin under the influence of these graphite materials as additive. The additives were added to urea formaldehyde resin at three levels of consumption of 1, 2 and 3%, and then medium density fiberboard (MDF) with a density of 750 kg/m3 was made from glued fibers. After making the board, the formaldehyde emission test was performed by desiccator method. Overall, MnO2-EG showed better results than control and two other graphite treatments. The best performance was resulted by MnO2-EG at level 3% so that reduced formaldehyde emission by about 61%. It seams the formaldehyde molecules absorbed into the expanded graphite layers were exposed to oxidation by manganese dioxide molecules. On the other hand, as the DSC test showed, the highest anthalopy reaction occurred in resin treated by MnO2-EG, indicating an increase in the reaction of formaldehyde molecules in the resin structure.
Management and Economics wood
Reza Hajihassani; Behbood Mohebi; Saeid Kazemi Najafi; Parviz Navi
Abstract
Abstract The present research work has investigated the physical and mechanical properties of hygro-thermally modified poplar (Populus deltoides) wood. The poplar wood blocks were treated hygrothermally at temperatures of 130, 150 and 170°C and for 20, 40 minutes as holding time. The physical and ...
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Abstract The present research work has investigated the physical and mechanical properties of hygro-thermally modified poplar (Populus deltoides) wood. The poplar wood blocks were treated hygrothermally at temperatures of 130, 150 and 170°C and for 20, 40 minutes as holding time. The physical and mechanical properties were determined for both treated and untreated wood. The properties; mass loss, collapse, specific gravity changes, dimensional stability, surface roughness, bending strength and modulus of elasticity, were determined prior to and after the treatment in all wood blocks. As expected, the hygrothermal treatment significantly improved the dimensional stability of the samples. It was also found that the hygrothermal treatment could increase collapse, surface roughness and modulus of elasticity due to the treatment. However, there were decreases in wood mass, specific gravity and bending strength of the treated poplar wood. It was revealed that the mass loss, decrease in the density as well as collapse in woos is correlated with treatment temperature as well as the holding time. While, raise of the treatment temperature as the holding time caused increase of the dimensional stability.
Composite wood products
Saeid Kazemi najafi; Ali Azimi dalrstani
Abstract
In this study, physical and mechanical properties of composites made of bark flour and polypropylene were studied and compared with those of wood flour-polypropylene composites. Bark flour content were adjusted at three levels (40, 50 and 60%) and compounded at absence and presence of 2% compatibilizer ...
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In this study, physical and mechanical properties of composites made of bark flour and polypropylene were studied and compared with those of wood flour-polypropylene composites. Bark flour content were adjusted at three levels (40, 50 and 60%) and compounded at absence and presence of 2% compatibilizer (MAPP) in a twin screw extruder to produce the bark flour-polypropylene composites. The wood flour-polypropylene composites also were manufactured at 60 filler weight wood flour loading. The results showed that water absorption and thickness swelling of composites containing bark flour increase with increasing bark flour content. The composites containing bark flour exhibited lower water absorption and thickness swelling than those made from wood flour. In absence of MAPP, bark content had no significant effect on flexural modulus of the composites but flexural strength and un-notched Izod impact strength significantly decreased with increase in bark content. The use of MAPP had no significant effect in increasing the mechanical properties. A comparison indicates that in absence of MAPP, bark flour-PP composites exhibited higher mechanical properties than wood flour-PP composite but in presence of MAPP, results were quite inversed.
Pulp and paper
Rabi Behroz; Hamed Unsi kord khelili; Saeid Kazemi najafi
Abstract
Effect of Kraft lignin as a compatibilizer on the short-term water absorption (2 and 24 hours) and mechanical properties of wood flour-polypropylene composites was studied. The black liquor of Chooka pulp and paper mill was acidified and Kraft lignin was extracted by precipitation. The extracted ...
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Effect of Kraft lignin as a compatibilizer on the short-term water absorption (2 and 24 hours) and mechanical properties of wood flour-polypropylene composites was studied. The black liquor of Chooka pulp and paper mill was acidified and Kraft lignin was extracted by precipitation. The extracted lignin at three levels of 2, 5 and 10 percent was mixed with wood flour by physical mixing method. All materials used were oven-dried. Wood flour, lignin and PP with or without MAPP were used to produce composites by flat hot press method. The results of this study indicated that generally lignin improved physical (short term water absorption) and mechanical properties (flexural modulus, flexural strength and impact strength). The bending test result showed that without MAPP, the composites with 2 and 10 percent lignin exhibited higher flexural modulus and strength, respectively. But at the presence of compatibilizer, the composites with 5 percent lignin exhibited the highest flexural modulus and strength. The composite with 2 percent of lignin exhibited higher flexural modulus and short-term water absorption rather than the composites with 2% MAPP. This result indicated positive effect of lignin in the composites. Also the composites with 10 percent lignin exhibited the highest impact strength and short-term water absorption. But there were no significant difference between the impact strength of composites with 5 and 10 percent lignin.
Physics and Mechanical Wood
Morteza Mostafazadeh mrznaki; Saeid kazemi najafi; Majid Chaharmahali; Reza Hajihassani
Abstract
In study, the influence of flour content and immersion time in water on the creep behavior of composites made from mixes PB (Particle Board) and MDF (Medium Density Fiber Board) flour and high density polyethylene (HDPE) waste and was investigated. Mixing was done by a twin screw extruder and the sample ...
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In study, the influence of flour content and immersion time in water on the creep behavior of composites made from mixes PB (Particle Board) and MDF (Medium Density Fiber Board) flour and high density polyethylene (HDPE) waste and was investigated. Mixing was done by a twin screw extruder and the sample was manufactured by flat hot press. Firstly, the modulus of elasticity and bending strength of various mixes PB and MDF flour-polyethylene composites (WPCS) were measured before performing the creep test.It was shown that the modulus of WPCs increases with the increase in mixes PB and MDF flour content from 60% to 70% and then decreases as the flour content reaches to 80%. It is found that the bending strengths of WPCs significantly and linearly decreases with the increase in flour content from 60% to 80%. The results showed that, the creep strain decreases as the lignocellulosic flour level increases. Water absorption has negative effect on creep behavior of mixes PB and MDF flour/HDPE composites. For all filler contents, it can be seen that the creep strain increases when the immersion time increases.
Physics and anatomy
Alireza Ghotibi far; Saeid Kazemi najafi; Rabi Behroz
Abstract
This research focused on the influence of content (5, 10 and 15 %) of glass fiber on the water absorption and thickness swelling of wood flour/E-glass fiber hybrid polypropylene composites without and with MAPP. The samples (strips with 10 mm thickness and 70 mm width) were made using a laboratory twin-screw ...
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This research focused on the influence of content (5, 10 and 15 %) of glass fiber on the water absorption and thickness swelling of wood flour/E-glass fiber hybrid polypropylene composites without and with MAPP. The samples (strips with 10 mm thickness and 70 mm width) were made using a laboratory twin-screw extruder. The water absorption and thickness swelling of the composites after 2h and 24h were determined. The results showed that adding glass fiber significantly increase water absorption and thickness swelling after 2h and 24h in absence of MAPP. Whereas in presence of 2% MAPP by addition glass fiber, no significant changes were observed in water absorption and thickness swelling of the composites after 2h and 24h. MAPP considerably decreased the water absorption and thickness swelling of the studied composites
Composite wood products
Majid Chahar mahal; Saeid Kazemi najafi; Mehdi Tajvidi; Reza Hajihassani
Abstract
Wood -Plastic panels were made from high density polyethylene (as resin) and MDF waste and particleboard waste (as natural fiber) at 60, 70 and 80% by weight fiber loading. Density and dimensions of the panels were 1g/cm3and 35*35*1 cm, respectively. Physical properties of the panels including equilibrium ...
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Wood -Plastic panels were made from high density polyethylene (as resin) and MDF waste and particleboard waste (as natural fiber) at 60, 70 and 80% by weight fiber loading. Density and dimensions of the panels were 1g/cm3and 35*35*1 cm, respectively. Physical properties of the panels including equilibrium moisture content, long term water uptake and thickness swelling behavior were studied.Results indicated that equilibrium moisture content, maximum water uptake and thickness swelling of wood plastic samples increased with the increase in fiber content from 60% to 80%. Moreover, samples with higher fiber content faster reach to saturation point.
Composite wood products
Majid Chaharmahali; Saeid Kazeminajafi; Mehdi Tajvidi; Mohammad ali Podineh poor
Abstract
The possibility of producing wood-plastic panels using melt blend method was studied in this research and mechanical properties of the panels including flexural modulus, flexural strength, screw and nail withdrawal resistance, and impact strength were studied.Wood -Plastic panels were made from high ...
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The possibility of producing wood-plastic panels using melt blend method was studied in this research and mechanical properties of the panels including flexural modulus, flexural strength, screw and nail withdrawal resistance, and impact strength were studied.Wood -Plastic panels were made from high density polyethylene (as resin) and MDF waste and particleboard waste (as natural fiber) at 60, 70 and 80% by weight fiber loading. Density and dimensions of the panels were 1g/cm3and 35*35*1 cm, respectively. Results indicated that the mechanical properties of the composites are strongly affected by the proportion of the wood flour and polymer in the material. Maximum values of flexural modulus of wood plastic panels were found at 70% fiber content in both methods. Flexural strength, screw and nail withdrawal resistance and impact strength of wood plastic composites reduced with the increase in fiber content from 60% to 80%.
Composite wood products
Saeid Kazemi najafi; Ali Shalbafan; Majid Charmahali
Abstract
Density profile of three types of medium density fiberboard (MDF) panels used in Iran market was studied through direct method and gradually removing of layer. Modulus of elasticity, bending strength, internal bond, water absorption and thickness swelling were also determined. The results show that the ...
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Density profile of three types of medium density fiberboard (MDF) panels used in Iran market was studied through direct method and gradually removing of layer. Modulus of elasticity, bending strength, internal bond, water absorption and thickness swelling were also determined. The results show that the shape of density profiles in all types of panels is nearly symmetric and normal, but the profil density in one was deeper, so it showed higher modulus elasticity and bending strength. No significant difference in internal bond was observed between different types of panels.
Physics and Mechanical Wood
Ghanbar Ebrahimi; Hossein Mahjob; Saeid Kazemi najafi
Abstract
Ultrasonic wave speed was measured in the longitudinal direction of Basswood on the top and bottom surfaces and center of lumbers during kiln drying in 3 Kiln load programs with final dry bulb of 80oC and different relative humidities. On the surfaces, wave speed decreased rapidly with MC declining from ...
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Ultrasonic wave speed was measured in the longitudinal direction of Basswood on the top and bottom surfaces and center of lumbers during kiln drying in 3 Kiln load programs with final dry bulb of 80oC and different relative humidities. On the surfaces, wave speed decreased rapidly with MC declining from green to FSP, but from FSP down to 7% moisture content wave speed did increased slowly. In the center of lumber, with decreasing MC from green to FSP, wave speed increased slowly, but by reducing MC to 7%, wave speed was rapidly increased. 5% MC, on the three surface of lumber, wave speed had no drastic difference. Results indicated that ultrasonic wave speed and MC of wood show a parabolic relationship. Further, results have shown that measuring ultrasonic wave speed is an appropriate method to control kiln drying program for hardwood lumber
Composite wood products
Majid Chaharmahali; Saeid Kazemi najafi; Mehdi Tajvidi
Abstract
The possibility of producing wood-plastic panels using two methods including melt blend and dry blend was studied in this research. Methods were compared with each other in order to select the best. Wood-Plastic panels were made from high density polyethylene (as resin) and particle board waste (as natural ...
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The possibility of producing wood-plastic panels using two methods including melt blend and dry blend was studied in this research. Methods were compared with each other in order to select the best. Wood-Plastic panels were made from high density polyethylene (as resin) and particle board waste (as natural fiber) at 60, 70 and 80% by weight fiber loading. Density and dimensions of the panels were lg/cm3 and 35*35*1 cm, respectively. Mechanical properties of the panels including flexural modulus, flexural strength, screw and nail withdrawal resistance, and impact strength were under investigation. Maximum values of flexural modulus of wood plastic panels were found at 70% fiber content in both methods. Flexural strength, screw and nail withdrawal resistance and impact strength of wood plastic composites reduced with the increase in fiber content from this is not a reduction 60% to 80% is increase. Mechanical properties of samples made with dry blend method were generally higher than those of samples made with melt blend method for an corresponding formulations.
