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.
Saman Ghahri; Mohammad Reza Abde; Farshid Abdoli
Abstract
In this research, Fir wood (Abies spp.) was thermally modified by retification process. The effect of modification process on physical and mechanical properties of fir wood were evaluated. For this aim, fir wood specimens with 12% moisture were modified in the steel tank with nitrogen gas medium at different ...
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In this research, Fir wood (Abies spp.) was thermally modified by retification process. The effect of modification process on physical and mechanical properties of fir wood were evaluated. For this aim, fir wood specimens with 12% moisture were modified in the steel tank with nitrogen gas medium at different temperatures (180 °C, 200 °C, and 220 °C) and 15 hours holding time. Physical properties such as wood density, volumetric swelling, dimensional stability and mechanical properties such as modulus of rupture (MOR), modulus of elasticity (MOE), shear and compression strength parallel to grain and impact strength of different modified wood specimens were evaluated. Results showed that by increasing treatment temperature, during modification process, water absorption and volumetric swelling were decreased and dimensional stability was improved. Also, results revealed that the mechanical strength of modified wood such as MOR, MOE, shear and compression strength parallel to grain and impact strength were decreased.
mohammad ghofrani; Anooshe Fazeli
Abstract
This study was carried out to investigate the effect of two nominal density levels of 800 kg/m3 and 1100 kg/m3 and two levels of industrial wood to cement ratios of 25:75 and 35:65 on mechanical and physical properties of wood cement composites. Boards were produced and then observed density of boards ...
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This study was carried out to investigate the effect of two nominal density levels of 800 kg/m3 and 1100 kg/m3 and two levels of industrial wood to cement ratios of 25:75 and 35:65 on mechanical and physical properties of wood cement composites. Boards were produced and then observed density of boards were calculated. The experimental boards were subjected to modulus of elasticity and modulus of rupture tests in accordance with EN 310. Internal bonding was evaluated according to EN 319. Water absorption and thickness swelling were evaluated after 2 and 24 hours immersion in water according to EN 317. Fire resistance was evaluated according to ISO 11925. Results indicated that bending properties of the boards, including modulus of elasticity and modulus of rupture, and internal bonding all increased with increase in density. That was attributed to the high compression and improved connection between fiber and cement matrix. Modulus of elasticity increased significantly as cement content was raised. Modulus of rupture values were inversely related to cement content. Increasing wood to cement ratio led to low internal bonding because the low amount of cement can be insufficient to cover the wood particles for effective bonding to resist the tensile forces applied during internal bonding test. As the board density increased, dimensional stability increased. Variations in the wood to cement ratio have been reported to significantly affect the dimensional stability of specimens. Water absorption and thickness swelling increased with the increase in wood to cement ratio. Fire resistance of specimens improved when the board density and cement content increased. All of the mechanical properties of boards produced in this study satisfied the EN 634-2 requirements.
Mohammad mahdi Mehrandish; Aisona Talaei; Mohammad Hadi Rezvani
Abstract
Flammability is one of the most important parameters that limits the range of wood use. Therefore, it is important to improve the fire retardancy properties of wood. The aim of this study was to evaluate the effect of modification with citric acid and its comparison with borax and ammonium chloride on ...
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Flammability is one of the most important parameters that limits the range of wood use. Therefore, it is important to improve the fire retardancy properties of wood. The aim of this study was to evaluate the effect of modification with citric acid and its comparison with borax and ammonium chloride on the flammability of paulownia wood. Test specimens were prepared and in vitro cylinders were saturated with chemical solutions at 10% depletion. Based on pre-treatment conditions, the modification was performed by heating with oven at different temperature and time levels. The fire performance of the samples was evaluated by measuring different parameters. The effect of different fire retardants on water absorption and short-term swelling of the specimens was also studied. The fire test showed that by treating the samples with citric acid and fire retardant materials, less mass reduction, flame retardation time and longer ignition time were obtained. These findings were attributed to the formation of a protective carbon layer by citric acid and fire retardant materials. The flame retardant properties of borax treatment yielded better results than those using citric acid and ammonium chloride. In addition, water absorption and dimensional stability were improved by the presence of citric acid and fire retardant agents. The results of FTIR spectra showed that the carboxylic acid groups reacted with the hydroxyl groups of the wood and increased the weight of the samples. Changes in the crystallinity indices of cellulose, carbonyl and hydroxyl were also obtained from FTIR spectra.
Composite wood products
Behzad Ghasemi; Farshid Faraji; Sahab Hedjazi
Abstract
Abstract In this research, the effect of using natural poly lactic acid polymer and the amount of MAPP coupling agent on the physical and mechanical properties of composite manufactured by sunflower stem flour was studied. For this purpose, three levels of PLA polymer including 50, 60 and 70% and tow ...
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Abstract In this research, the effect of using natural poly lactic acid polymer and the amount of MAPP coupling agent on the physical and mechanical properties of composite manufactured by sunflower stem flour was studied. For this purpose, three levels of PLA polymer including 50, 60 and 70% and tow levels of MAPP including 4 and 6 percent based on dry weight of polymer were used as variables. Then, the physical and mechanical properties of the test specimens including dimensional stability, resistance and tensile modulus, resistance and flexural modulus and impact resistance were measured. The results showed that increasing the amount of PLA polymer and reducing the share of sunflower stem flour and increasing MAPP up to 6 percent, increased the flexural, tensile and impact resistances and improved dimensional stability of the composites. But in contrast, the tensile and bending modulus of composites were reduced. However, by reviewing the results, it was found that the physical and mechanical properties of the composites made with this polymer and the particles of sunflower stem flour were competitive with other composites made with other chemical polymers and in some cases it was better than them.
Composite wood products
Habib alah Khademieslam; Mehdei Kalagar
Abstract
In this investigation, tensile and physical properties of polypropylene (as matrix)/wheat straw fiber/paper mill sludge (as filler) composites was studied. The ratio of wheat straw fiber/ paper mill sludge was selected as 40/0, 30/10, 20/20, 10/30 and 0/40 (w/w) were used. Also, for better ...
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In this investigation, tensile and physical properties of polypropylene (as matrix)/wheat straw fiber/paper mill sludge (as filler) composites was studied. The ratio of wheat straw fiber/ paper mill sludge was selected as 40/0, 30/10, 20/20, 10/30 and 0/40 (w/w) were used. Also, for better compatibility between the two phases 3% MAPP as coupling agent was used. Mixing process was done in twin screw internal mixer extruder, and then composite samples were manufactured by injection molding. Result indicated that the tensile modulus of elasticity improved with increasing fillers and also it was observed that the toughness of composite increased when compared to the pure PP, while due to the usage of more paper sludge, these properties was improved. Tensile strength of composite decreased with adding 40% wheat straw fiber, but with addition of sludge tensile strength increased significantly. Adding wheat straw in PP matrix and its hydrophilic properties resulted in the highest rates of water absorption and thickness swelling. However, adding paper sludge and lower amount of lignocellulosic material, and the compatibilizer noticeably decreased the physical properties due to better bonding between two phases.
Composite wood products
Saeid Ismaeilimoghadam; Mohammad Shamsian; Ali Bayat Kashkoli; Behzad Kord
Abstract
This research with aim of evaluation the effect of chemical treatment of wood flour on physical, mechanical and morphological properties of polypropylene-nano SiO2 hybrid nanocomposite were done. For this purpose, wood flour with sodium hydroxide and benzyl chloride to chemically treatment. For ensure ...
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This research with aim of evaluation the effect of chemical treatment of wood flour on physical, mechanical and morphological properties of polypropylene-nano SiO2 hybrid nanocomposite were done. For this purpose, wood flour with sodium hydroxide and benzyl chloride to chemically treatment. For ensure the chemical treatment, Fourier transform infrared (FTIR) spectroscopy tests was done on the treated and untreated wood flour. Wood flour at 60% weight ratio with polypropylene with 4% maleic anhydrate grafted polypropylene coupling agent in extrusion were mixed. Also Nano SiO2 with 0, 1, 3 and 5% as filler was used. The sample specimen were manufactured by using injection molding techniques. Then mechanical tests such as bending resistance and modulus and physical tests such as water absorption and thickness swelling according to the ASTM standard was done on the samples. Also for morphological investigation on the Nano composites from Scanning Electron Microscopy (SEM) was used. Results showed that the bending resistance and modulus increased with effect of chemical treatment but water absorption and thickness swelling decreased. With increase of Nano SiO2 to 3% the mechanical properties increased but adding further amount Nano particles reduced the mechanical properties. With increase of SiO2 Nano particles to 5% the water absorption in Nano composites were increased, but thickness swelling was decrease. The results of SEM showed an improvement in interface between filler and matrix with effect of chemical treatment Also transmittance of Nano SiO2 to 3% levels was good.
Composite wood products
Saeed Khojasteh Khosro; Saeed Khojasteh Khosro; Mohammad Hasan Payan; Seyyed Mehdi Seyydi
Abstract
In the present research improvement of dimensional stability and mechanical properties of gypsum particleboard by using white cement was investigated. In manufacturing gypsum particleboard, Micronize gypsum was used in three levels of 2.5:1, 2.75:1 and 3:1 to dried mass of wooden materials. White cement ...
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In the present research improvement of dimensional stability and mechanical properties of gypsum particleboard by using white cement was investigated. In manufacturing gypsum particleboard, Micronize gypsum was used in three levels of 2.5:1, 2.75:1 and 3:1 to dried mass of wooden materials. White cement was added in 2 levels of 5 and 10% based on oven dried mass of gypsum to reinforce gypsum particleboard properties. Water absorption, thickness swelling after 2 and 24 hours immersion in water, bending strength, modulus of elasticity and internal bond strength were measured. Vicat needle method was used to investigate the effect of adding cement on setting time of gypsum. The results showed that adding 5% cement based on oven dried mass of gypsum, increased setting time and also mechanical properties. Adding cement over than 5% (10%), significantly improved dimensional stability but reduced setting time of gypsum and mechanical properties of the boards. On the other hand, results indicated that using Micronize gypsum to 2.75 times to dried mass of wooden materials, increased bending strength and modulus of elasticity. Increasing gypsum in to 3 times, reduced bending strength and modulus of elasticity, but improved internal bond strength and dimensional stability.
Sarveh Hosseinzadeh; Maryam Ghorbani; Porya Biprva
Abstract
This research was conducted to determine the physical properties of poplar wood treated with silica colloidal nanoparticles prepared from rice husk using ash making and alkaline digestion. Test samples were prepared according to ASTM-D1037 standard with the dimension of 2×2×2 cm and then ...
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This research was conducted to determine the physical properties of poplar wood treated with silica colloidal nanoparticles prepared from rice husk using ash making and alkaline digestion. Test samples were prepared according to ASTM-D1037 standard with the dimension of 2×2×2 cm and then were impregnated ina cylinder according to Bethell method applying five concentration levels of soluble colloidal silica nanoparticles (0, 1.2, 1.7, 2.2 and 3.2%). Nanoparticle retention and absorption, density changes, water absorption, and anti-swelling efficiency (ASE) were determined. Nano silica absorption was determined as 119.8, 169.5, 196.3 and 214.7 % corresponding to 1.2, 1.7, 2.2 and 3.2 % nanoparticle addition, respectively. Nano-silica retention in the lowest and the highest treatment level were 1.2 and 9.3%. Results showed that the density increased from 0.37g/cm³ in control samples to 0.40 g/cm³ at the highest level of nano-silica absorption. Water absorption increased by increasing nano-silica absorption. However, dimensional stability of impregnated samples increased. After the longest immersion time, average swelling volume of the sample impregnated with nano-silica was decreased in comparison with the control sample. With increasing nano-silica absorption, anti-swelling efficiency of impregnated samples treated at the 1.2, 1.7, 2.2 and 3.2 % level and immersed for 168h was 36.5, 42.9, 34.7 and 26.8 %, respectively.
Composite wood products
Amir Nourbakhsh; Abolfazl Kargarfard; Fardad Golbabaei
Abstract
The goal of this study was to investigate the use of bagasse fibers as raw material for making laboratory medium density fiberboard (MDF). Effect of treatment (with maleic anhydride and without maleic anhydride) of fibers and the press temperatures (180 ºC , 190 ºC , and 200 ºC) ...
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The goal of this study was to investigate the use of bagasse fibers as raw material for making laboratory medium density fiberboard (MDF). Effect of treatment (with maleic anhydride and without maleic anhydride) of fibers and the press temperatures (180 ºC , 190 ºC , and 200 ºC) on the mechanical and dimensional stability properties of MDF panels were determined. Physical (thickness swelling, water absorption, and swilling in water at ambient temperatures and in steam for 12-216 h.) and mechanical properties (modulus of rupture, modulus of elasticity, and internal bond strength) of the panels were determined according to the procedure of EN standards.This study showed all MDF panels made from bagasse fibers treated with maleic anhydride (MA) at 190 ºC press temperature had the highest values among the other types of specimens for general purpose boards. The thickness swelling and water absorption value with treated bagasse fibers and 190 ºC press temperature were very lower than all MDF panels. Treated bagasse fibers at 190 ºC show a minimum steam absorption. The absorption of steam increase with increase in time from 2 to 120 h in all the six treatments. Beyond 120 h. no additional absorption of steam is found in any of the six MDF boards.
Delaram Drakhshandeh; Behbood Mohebi; Saeed Mahdavi
Abstract
This research was carried out to study the influence of acetylation on paper dimensional stability. Specimens from printing paper and Texon paperboard were oven dried and then treated with acetic anhydride at 120°c for 30 and 60 min without catalyst. Acetylated papers were soaked in water for 2 and ...
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This research was carried out to study the influence of acetylation on paper dimensional stability. Specimens from printing paper and Texon paperboard were oven dried and then treated with acetic anhydride at 120°c for 30 and 60 min without catalyst. Acetylated papers were soaked in water for 2 and 24 h. Afterwards, bulking effect of the acetylation and thickness swelling of the specimens as well as anti-swelling-effect (ASE) were determined in the treated specimens.
Results revealed that the bulking of the specimens were increased by reaction time. However, in case of Texon, it was slowed down after 30 min of the reaction time. The thickness swelling of the treated specimens was significantly reduced after soaking in water for 2 and 24 h compared with untreated samples. As it was expected the acetylation increased ASE in Texon and the printing papers.
