Reza Hajihassani; seyedeh masoomeh; Saman Ghahri; Kamyar Salehi
Abstract
AbstractThe purpose of this study was to investigate the effect of heat treatment on bio-durability and some physical and mechanical properties of beech (Fagus Sp.) and pine (Pinus Sp.). Thermo-wood samples were prepared from beech and pine species based on thermo-D process. Heat-treated and untreated ...
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AbstractThe purpose of this study was to investigate the effect of heat treatment on bio-durability and some physical and mechanical properties of beech (Fagus Sp.) and pine (Pinus Sp.). Thermo-wood samples were prepared from beech and pine species based on thermo-D process. Heat-treated and untreated wood specimens were evaluated after exposing to brown rot fungus for 16 weeks. The laccase activity and its effect on mass loss and wood density were investigated. Results showed that deterrence value of heat treatment on mass loss caused by brown rot fungus have been 76.92% and 44.32% in beech and pine wood, respectively. So, laccase activity and its efficiency on mass loss of control specimens was more than heat treated wood. The results also showed that thermally modification at high temperatures reduced wood density. However, it had deterrent effect on decrease of density caused by brown rot fungus activity. Moreover, some mechanical properties including impact strength and compression parallel to grain of wood specimens were measured. The results generally showed that thermal modification improves the bio-durability of both wood species. The results also revealed reduction of mechanical properties due to heat treatment except compression parallel to grain.
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.
Saman Ghahri; Reza Hajihassani; Kamyar Salehi; Fardad Golbabaei
Abstract
In this study, the mechanical properties of kenaf cement composite were investigated using different amounts of kenaf particles (mixture of kenaf core and bark and kenaf core particles). Kenaf-cement composites were manufactured at different levels (10, 15 and 20%) of different kenaf particles. Also, ...
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In this study, the mechanical properties of kenaf cement composite were investigated using different amounts of kenaf particles (mixture of kenaf core and bark and kenaf core particles). Kenaf-cement composites were manufactured at different levels (10, 15 and 20%) of different kenaf particles. Also, Portland cement and calcium chloride (as cement accelerating additive) were used in this research. Calcium chloride and water were mixed well and then kenaf particles were added to the mixture. At next stage, cement was added to the prepared mixture and all component were mixed well. Prepared mixture was molded to the wooden mold and kenaf cement composites were produced. The results obtained from mechanical evaluation of kenaf-cement composites showed the highest bending strength in 10% kenaf bark-cement composites. Also results revealed that highest modulus of elasticity of 10% kenaf core-cement products were obtained. The results of this research revealed the potential of kenaf particles as reinforcement in cement composite production.
Reza Hajihassani; Mohammad Sadeghipour ranjbar; Saman Ghahri
Abstract
The aim of current research was to investigate physical and mechanical properties of particle board made from pistachio lignocellulosic residue. The raw materials were prepared from Sirjan (Kerman province). Sample boards were made from pistachio lignocellulosic residue at two press time (4 and 5 minutes), ...
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The aim of current research was to investigate physical and mechanical properties of particle board made from pistachio lignocellulosic residue. The raw materials were prepared from Sirjan (Kerman province). Sample boards were made from pistachio lignocellulosic residue at two press time (4 and 5 minutes), two press temperature (170 and 180ᴼc) and three compositions (100 percent, 90:10 and 80:20 pruning residue to pistachio shell). The specimens were physically and mechanically tested as water absorption, thickness swelling, bending strength, modulus of elasticity and internal bonding. Afterward, the results were analyzed based on a complete randomized design (CRD) under a factorial experiment. Results revealed that pruning residues of pistachio trees can be used as suitable raw materials for particle board production. Moreover, pistachio shell can be used up to 10 percent in raw material composition, but physical and mechanical properties of boards will be reduced in higher consumption quantities.Keywords: Particle board, pruning residue, pistachio shell, composition, physical and mechanical properties
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.
Reza Hajihassani; Saman Ghahri; Kamyar Salehi; Fardad Golbabaei; seyedeh masoomeh
Abstract
Abstract In the current research, surface properties and failure modes of modified poplar wood (Populus deltoides) by hygrothermal treatment were evaluated. For this aim, the effect of variable factors included hygrothermal temperature (three levels: 130, 150 and 170°C) and holding time (two levels: ...
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Abstract In the current research, surface properties and failure modes of modified poplar wood (Populus deltoides) by hygrothermal treatment were evaluated. For this aim, the effect of variable factors included hygrothermal temperature (three levels: 130, 150 and 170°C) and holding time (two levels: 20 and 40 minutes) on poplar wood specimens properties (contact angle and surface roughness) prior to and after planning were investigated. The surface characteristics and failure modes were evaluated for both treated and untreated wood specimens. The results revealed that surface roughness of poplar wood was enhanced due to the hygrothermal treatment in both states of before and after planning. It was also found that the hygrothermal treatment decreased contact angle of distilled water. The bending strength of specimens was reduced by hygrothermal treatment. According to the results, failure modes of hygrothermally treated specimens were simple and compression types in bending strength test. Keywords: Surface roughness, contact angle, bending strength, failure mode
Amir Nourbakhsh; Abolfazl Kargarfard; Reza Hajihassani; Saman Ghahri; Fardad Golbabaei
Abstract
In this study, the resistance properties of nanocomposite plastic wood produced using 5 levels of cellulosic wastes (bagasse, corn stalk, rice stalk, sunflower stem and canola stem), three levels of nanomaterials (carbon nanotubes, nano silica, nanoclay) ) And urban polymer wastes (PP polypropylene and ...
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In this study, the resistance properties of nanocomposite plastic wood produced using 5 levels of cellulosic wastes (bagasse, corn stalk, rice stalk, sunflower stem and canola stem), three levels of nanomaterials (carbon nanotubes, nano silica, nanoclay) ) And urban polymer wastes (PP polypropylene and HDPE heavy polyethylene, etc.) were investigated. In order to chemically bind the wood / polymer fiber composites, chemicals and reinforcers (pairing agents) have been used due to the hydrophilic properties of cellulose fibers and plastic drainage. Extruders and hot presses were used to study the mechanical properties and bonding of composites. The results showed that the use of HDPE heavy polymer wastes increased tensile strength, flexural modulus and impact resistance to polypropylene wastes. Regarding the use of agricultural wastes and wastes in the construction of wood-plastic composites, in general, the results have shown that the addition of agricultural waste wastes in several types of plastic wood has significantly improved the bending and tensile properties. Among them, the bagasse stem has a significant advantage over other lignosullose materials. The use of polymer waste and agricultural waste using nano-silica has shown the best results of resistances. In general, the results have shown that the use of agricultural fiber wastes as reinforcers in plastic wood polymers have the expected mechanical properties.
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.
