Aisona Talaei; Mohammad Hadi Rezvani; Hosseinali Rajabi Cham Heidari
Abstract
The widespread use of chemically/thermally modified wood in outdoor applications and in environments with high relative humidity and high temperature has doubled the importance of using hydrophobic monomers. To evaluate the effect of fluorocarbon modification as a binder on the physical properties and ...
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The widespread use of chemically/thermally modified wood in outdoor applications and in environments with high relative humidity and high temperature has doubled the importance of using hydrophobic monomers. To evaluate the effect of fluorocarbon modification as a binder on the physical properties and chemical structure of paulownia wood, thermal modification was performed at two temperature levels of 150 and 160°C and chemical modification with fluorocarbon at two levels of 15 and 25%. Chemical/thermal modification causes the fluorocarbon monomer and heat to be uniformly transferred into the wood and to reduce its hydrophilicity by causing chemical changes in the wood structure. Specimens were divided into control, thermal and thermal fluorocarbon treatment groups. The thermal fluorocarbon treatment caused modification of the hydroxyl groups and hydrophobicity in specimens. Infrared spectroscopy confirmed the presence of fluorocarbons and bonding with wood polymers. The fluorocarbon reaction resulted in chemical changes, weight gain and bulking of the specimens. The water uptake and volumetric swelling of the heat-treated fluorocarbon specimens were lower than the control and heat-treated ones. Improvement of water repellency efficiency and anti-swelling efficiency of thermal fluorocarbon specimens increased the dimensional stability compared to the thermal control and created a super hydrophobic and leak-resistant coating on the cell walls and inside the lumens. It was attributed to the greater penetration of fluorocarbons and the reduction of wood porosity.
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.
Management and Economics wood
Aisona Talaei; Mohammad Hadi Rezvani
Abstract
In this research the effect of chemical modification with Polycrease ECR on the functional performance of poplar wood to use as wood polymer were investigated. Polycrease ECR the modified dimethyloldihydroxy-ethyleneurea (DMDHEU) was used for chemical modification of wood by impregnation method. Specimens ...
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In this research the effect of chemical modification with Polycrease ECR on the functional performance of poplar wood to use as wood polymer were investigated. Polycrease ECR the modified dimethyloldihydroxy-ethyleneurea (DMDHEU) was used for chemical modification of wood by impregnation method. Specimens prepared according to the ASTM standard and treated in two levels of 30 and 50%. Modification process of specimens were performed at 24 hours in temperature of 120°C. Functional performance including Weight percent gain (WPG), bulking, long term water absorption and volumetric swelling in 8 weeks, bending strength (MOR) and modulus of elasticity (MOE), compression strength parallel to the grain, shear strength and withdrawal resistance of screw parallel to the grain was measured. Two-way analysis of variance (ANOVA) was used for statistical analysis. Obtained results of modified specimens were compared with untreated control. Results showed that modification with Polycrease ECR had significant effects on physical and mechanical properties in treated specimens. Chemical modification in 30% level, lead to reduce long term water absorption and volumetric swelling. Reduction in mechanical properties were not considerable. Chemical modification with Polycrease ECR in 30 % level compared to 50 % level, showed better physical and mechanical properties. Generally, influence of chemical modification on the physical properties (long term water absorption and volumetric swelling) were dominant.
Management and Economics wood
Neda Esmaeeli; Maryam Ghorbani; pourya biparva
Abstract
This research was conducted to determine the optimal conditions for chemical modification of poplar wood with glutaraldehyde and its effect on the physical properties of products. Test samples were prepared according to the standard ASTM-D1037 and impregnated in the laboratory cylinders with Glutaraldehyde ...
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This research was conducted to determine the optimal conditions for chemical modification of poplar wood with glutaraldehyde and its effect on the physical properties of products. Test samples were prepared according to the standard ASTM-D1037 and impregnated in the laboratory cylinders with Glutaraldehyde at a concentration of 10% by using vacuum-pressure method. Modification reaction was done in two procedure. Heating first in the laboratory cylinder (Hydrothermal) for 4 hour and second in oven for 4 level 4,12,24,48 and 48hours. Weight percent gain of modified by hydrothermal and oven method was measured 2.10, 9.26, 10.02, 11.40 and 14.15% respectively. Chemical modification with glutaraldehyde by hydroxyl group's substitution, reduced the uptake of water and swelling of poplar wood. So that at the end of soaking in water the heating in the oven for 48 hours with minimum water absorption and dimensional changes in the 57.32 and 12.08 respectively, and highest bulking, ASE and ASE′ in 8.31,67 and 35.51% respectively was selected as the optimal level. This improvement compared to other modification levels demonstrates the forming of permanent Cross-linking of acetal that increased by Prolongation of the heating time.
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.
