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.
Ali Pesaraklu; Mohammadreza Dehghani firoz abadi; Abolfazl Karegarfard; Taghi Tabarsa
Abstract
The objective of this study was to manufacture water resistant kenaf stalk particleboard.Twenty seven boards were produced using 170 °C steam treated kenaf particles, 30 and 60minute treatment time and three resin types include urea-formaldehyde, melamineformaldehydeand a mixture of fifty percent ...
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The objective of this study was to manufacture water resistant kenaf stalk particleboard.Twenty seven boards were produced using 170 °C steam treated kenaf particles, 30 and 60minute treatment time and three resin types include urea-formaldehyde, melamineformaldehydeand a mixture of fifty percent each. Physical and mechanical properties weremeasured and the results analyzed in a complete random design plan and by the factorialanalysis. The results showed that boards made from treated particles with 60 minute treatmenttime and Urea Formaldehyde resin had the highest bending strength. Modulus of elasticity(MOE) improved with an increase in treatment time. The greatest MOE was achieved with theboards produced using urea-formaldehyde and the greatest MOE was achieved with the boardsbonded with urea-melamine-formaldehyde resin. Moreover, with increasing treatment time from30 to 60 minutes internal bond strength (IB) reduced. Thickness swelling and water absorptionof the boards was significantly improved with increasing treatment time.
Composite wood products
Hamid reza Adalat; Taghi Tabarsa; Marzyeh Raeisi
Abstract
For this study 10 logs of Paullowina.furtunie from Shastkalateh forest of Gorgan in Iran were selected randomly. After that, 45 clear flat swan specimens prepared and dried to 5% moisture. Density of each log and thickness of specimens were measured. Three levels of compression percent (16%, 33% and ...
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For this study 10 logs of Paullowina.furtunie from Shastkalateh forest of Gorgan in Iran were selected randomly. After that, 45 clear flat swan specimens prepared and dried to 5% moisture. Density of each log and thickness of specimens were measured. Three levels of compression percent (16%, 33% and 50%) and temperature (130°C, 145°C and 160°C) were the variables. The physical properties of specimens such as spring back, compression set and thickness swelling were calculated. Also, MOE, MOR and impact resistance of specimens were evaluated. In order to have accurate examination, microscopic images were taken. Results show that, with increasing in compression percent, the amounts of spring back and thickness swelling enhance. Densification with 16% compression, yields deformation in elastic region while 33% and 50% compression, causes more compression set. The more compression percent, the more mechanical strengths and the highest strength attained in 50% compression. The effect of temperature was insignificant mostly. Finally, the proper treatment for Paullownia densification, was 130°C and 50% compression. Microscopic images asserted the above results and illustrated that, the enhancing of densification above 50% compression is possible.
