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.
Management and Economics wood
Reza Jazayeri; Reza Hajihassani; Sedighe Nazari
Abstract
The main purpose of this study was to evaluate the effect of hydrothermal treatment with boric acid impregnation on some physical and mechanical characteristics and fire resistance of poplar (Populus nigra) and radiata pine (Pinus radiata) wood. In this study, two times of 60 and 90 minutes with two ...
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The main purpose of this study was to evaluate the effect of hydrothermal treatment with boric acid impregnation on some physical and mechanical characteristics and fire resistance of poplar (Populus nigra) and radiata pine (Pinus radiata) wood. In this study, two times of 60 and 90 minutes with two temperatures of 150○C and 180○C were used for the hydrothermal treatment, and boric acid with concentrations of 1, 3 and 5% dissolved in water used for the impregnation treatment. The measurement of the characteristics, including bending strength, impact resistance, volumetric swilling and fire resistance (weight loss due to fire) were done by ASTM-D143, ASTM-D256, ASTM 4446-2002 and ISO 11925 standards, respectively. About fire resistance, 5% boric acid treatment showed the least weight loss due to burning in the wood of two species. As a result of the hydrothermal treatment alone, the fire resistance was even lower than the control. In this regard, the combination of hydrothermal treatment with boric acid treatment resulted in results close to those of hydrothermal with boric acid treatment. Positive effect of hydrothermal treatment on the improvement of dimensional stability, is considered as one of the results of the present study. The temperature of 180○C with a time of 90 minutes reduced the swelling of poplar and radiata pine by about 36.8 and 42%, respectively. Regarding impact resistance, the effect of hydrothermal treatment on the wood of both species and the effect of boric acid treatment on radiata pine wood were negative. Hydrothermal treatment at a temperature of 180○C and with a time of 90 minutes decreased the impact resistance by 28.2% in the wood of both species, and 5% boric acid treatment caused a 13.3% decrease in this property in radiata pine wood.
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.
Abolfazl Kargarfard; Amir Nourbakhsh; Reza Jazayeri; ّFardad Golbabaei
Abstract
The objective of the present study was the utilization of rose flower residues for the production of medium density fiberboard. MDF was produced applying two moisture gradients of 0 and 4% between surface and core layer, two press temperatures of 175 and 185 °C and three pressing times ...
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The objective of the present study was the utilization of rose flower residues for the production of medium density fiberboard. MDF was produced applying two moisture gradients of 0 and 4% between surface and core layer, two press temperatures of 175 and 185 °C and three pressing times of 3,4 and 5 minutes. The mechanical and physical properties of the boards were measured and statistically analyzed using factorial experiment and complete randomized design. In case statistical difference was observed between the averages, then Duncn multiple range test was used for grouping of the averages. The results revealed that the moisture gradient statistically influenced the flexural strength and internal bonding of the boards. In both moisture gradients, the internal bond of the boards increased and the maximum was reached when 5 minutes pressing time was applied. The pressing time also statistically influenced the thickness swelling and the lowest values were measured on boards pressed for five minutes. Generally, the strength properties of the boards were in accordance with the required specification of EN standard, which indicates that rose flower residue can be considered as a suitable raw material for medium density fiberboard production.
