Chemical conversion
Zahra Daeepour; amir lashgari; Mehran Roohnia; Ahmad Jahan latibari; Vahid Safdari
Abstract
Background and objectives: Nowadays, the importance of treatments such as water washing and ethanol-acetone washing to improve the acoustic properties of wood has been noticed by the makers of musical instruments. Wood extractives are in the list of those materials that often do not have a construction ...
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Background and objectives: Nowadays, the importance of treatments such as water washing and ethanol-acetone washing to improve the acoustic properties of wood has been noticed by the makers of musical instruments. Wood extractives are in the list of those materials that often do not have a construction role, and their purposeful and correct evacuation can lighten the wood without reducing the stiffness. Carrying out pre-treatments such as fermentation with bread yeast (before water washing and ethanol-acetone washing processes) can lead to the extraction of more extractable substances from wood. In this study, the effect of water washing and ethanol-acetone washing treatments as well as fermentation pre-treatment on the acoustic properties of Ash wood (Fraxinus excelsior) has been investigated.Methodology: Ash wood species (Fraxinus excelsior) was prepared from the wood of a commercial timber and 38 small radial beams with nominal dimensions of 150×12×2 mm (longitudinal×radial×tangential) were extracted from the hardwood. After reaching the equilibrium humidity of 12% in air-conditioned conditions, the selected samples were subjected to the forced vibration test in the free-free beam in order to measure the basic physical and acoustic characteristics. After that, the initial tests were randomly divided into two groups of 19 tests. The first group without pretreatment and the second group with fermentation pretreatment were placed in the process of removing the extractives by water and then by ethanol-acetone mixture. After each step of water washing and removing the extractive substances soluble in ethanol-acetone mixture, the forced vibration test in the free-free beam was performed on the samples and the acoustic properties of the samples were measured.Results: Water washing without pretreatment with bread yeast caused a slight decrease and with pretreatment, it caused a significant decrease in density values (respectively: 1.75 and 7.39%). While the process of removing extractives (with and without pretreatment) by ethanol-acetone mixture caused a significant decrease in density values (Respectively: 2.27 and 8.71%). The modulus of elasticity values showed a significant decrease due to water washing without pretreatment and with pretreatment. (Respectively: 11.37 and 16.47%). The process of removing the extractives by ethanol-acetone mixture also resulted in a significant decrease in the modulus of elasticity values in untreated and pretreated samples (Respectively: 13.87 and 20.93%). Water washing without pre-treatment with bread yeast and with pre-treatment has caused a significant decrease in the values of damping factor, among which the pre-treated samples had a greater percentage of drop in the values of damping factor (Respectively: 13/87 and 20.93%). The process of removing the extractive materials by ethanol-acetone mixture as washing has caused a significant decrease in the damping factor values, which among the pre-treated samples showed a greater percentage drop in the values resulting from this property (Respectively: 3.03 and 18.01%). In this factor, the process of removing the extractive substances soluble in ethanol-acetone mixture (with and without pretreatment) has resulted in a greater drop in damping values (respectively: 6.67% and 20.85%). Acoustic conversion efficiency due to water washing process without pretreatment with baker's yeast caused a slight increase, while pretreatment caused a significant increase in acoustic conversion efficiency values (Respectively: 0.44 and 25.24%). The process of removing extractive materials by ethanol-acetone mixture also caused a significant increase in the acoustic conversion efficiency values, which among the pre-treated samples showed a higher growth percentage in the values of this characteristic (Respectively: 3.41 and 28.90%). Both water washing methods and ethanol-acetone mixture washing were effective in improving the physical (density) and acoustic properties (modulus-elasticity, damping and acoustic conversion efficiency). Meanwhile, the effect of ethanol-acetone mixture washing was more than the effect of water washing. Fermentation pretreatment with bread yeast improved the performance of water washing and ethanol-acetone mixture washing treatments.
nazanin salehi; Javad Torkaman; ramin naghdi; Mehran Roohnia
Abstract
The knot is the branch impact on the tree's trunk which reduces the quality of the wood. Knots or occlusion branches are the most important factor in the grading of woods. The purpose of this research is to detect and distinguish the size of the knot in the beech tree stem by non-destructive stress wave ...
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The knot is the branch impact on the tree's trunk which reduces the quality of the wood. Knots or occlusion branches are the most important factor in the grading of woods. The purpose of this research is to detect and distinguish the size of the knot in the beech tree stem by non-destructive stress wave method. In this research, five one-meter stems were examined and according to the knot size, the stems were classified into four parts without knots, with small, medium and large knots. By using the FAKOPP microsecond timer device, stress waves were passed along the length of the stem and the width of the knots in the four parts of the stem. The amount of the stress waves velocity were calculated according to the transit time of the stress waves and also percentage of the Relative Velocity decrease of Stress waves were calculated. Analysis variance of the data showed between the four parts there is a significant difference at the 95% confidence level. The results showed that the size of knot has effective on the Relative Velocity decrease of Stress waves in the beech tree stem. As the knot gets bigger, its angle decreases with the main stem axis. consequently more length is placed in the stem, and the speed of its occlusion increases. In this method,very small knots whose percentage of the Relative Velocity decrease of Stress waves was less than 10% were not detected. Therefore, for small, medium and large knots, the range of Relative Velocity decrease of Stress waves were obtained 10-20%, 20-45% and more than 45%, respectively.
Mostafa Kohantorabi; Amir Hooman Hemmasi; Mohammad Talaei poor; Mehran Roohnia; Behzad Baziyar
Abstract
One of the problems of non-destructive tests in the detection of the inhomogeneities in wood and wood products is their location relative to the vibrating node and antinode. Thus, the hidden inhomogeneities located at the vibration node in such materials may not have any effects on the dynamic modulus ...
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One of the problems of non-destructive tests in the detection of the inhomogeneities in wood and wood products is their location relative to the vibrating node and antinode. Thus, the hidden inhomogeneities located at the vibration node in such materials may not have any effects on the dynamic modulus of elasticity and may not be detectable. In this study, we investigated the development of simple end-to-end joint in oak beams (Quercus castaneifolia) with dimensions of 72×4×2 cm (longitudinal×Radial×Tangential), with blocks removed from the areas of 0.06 and 0.50 cm of the beam length. The blocks were removed from the same beam as the joint was developed. The results indicated that developing a joint in 0.50 cm of the beam length has no significant effect on values obtained from the dynamic modulus of elasticity while creating this joint in 0.06 cm of the beam length has a significant effect on values obtained from the dynamic modulus of elasticity. Also, in both joints, the damping and acoustic converting efficiency values were increased and decreased, respectively. The amount of these changes was more in the area of 0.06 cm of beam length. In general, it can be said that due to the effect of vibrating node and antinode and on the other hand, the location of the joint in both areas, the acoustic conversion efficiency factor is a suitable factor to estimate the location of the joint or the inhomogeneity itself.
Physics and Mechanical Wood
Parastoo Majdabadifarahani; Mehran Roohnia; amir lashgari
Abstract
DOR:98.1000/1735-0913.1398.34.87.66.1.1585.1588 This study deals with the possibility of evaluation and estimating the wood density in Quercus castaneifolia and Fagus orientalis. Wood samples were prepared and cut firstly in 4×20×30 cm (thickness×width×length). Then their density ...
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DOR:98.1000/1735-0913.1398.34.87.66.1.1585.1588 This study deals with the possibility of evaluation and estimating the wood density in Quercus castaneifolia and Fagus orientalis. Wood samples were prepared and cut firstly in 4×20×30 cm (thickness×width×length). Then their density was calculated after 72 hours of conditioning in an oven at 60°C temperature. In thermography process, the temporal temperature was monitored in 1st, 5th, 10, 20, 30, 45 and 60th minutes of cooling (monitoring steps). Investigating the effects of shape factor and dimension on thermographic density evaluation errors, the specimens were cut down in two more steps to 3×20×30 cm and 2×15×20 cm and the course of thermography experiments was repeated. The relationships of shape factor, density and the ratio of density to the shape factor with the logarithmic cooling rate were evaluated separately. Results showed that density without considering the shape factor variations was not sufficiently correlated to the cooling rate. But the ratios of the density to their proper shape factors were promising for the density evaluations from the cooling rates. However, it is suggested to revise this non-destructive method using a larger variety of the wood specimens and species.
Physics and Mechanical Wood
Mehran Roohnia; Ahmad Jahanlatibari; Behzad Behnam; Jamshid Zarrinmehr; Mostafa Kohantorabi; Negin Manouchehri; Ajang Tajdini
Abstract
Reaching to the technology of acoustical Tomography and imaging, this project was ordered for facilitating the work for green space researchers and managers in urban standing trees. Comparing the sensors and micro-second timers with those of a certified European device in radial to tangential and longitudinal ...
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Reaching to the technology of acoustical Tomography and imaging, this project was ordered for facilitating the work for green space researchers and managers in urban standing trees. Comparing the sensors and micro-second timers with those of a certified European device in radial to tangential and longitudinal directions showed a good agreement for the Iranian made device. So, a new horizon was opened for the researchers of this approach supported by the local scientific knowledge and technology. Holding this technology, the selected trees concerning the collar defect symptoms were firstly inspected visually, then the visual accuracy was monitored by sonic tomography. Some trees were extremely defected internally, while the visual inspection showed their intactness (9 from 23). Meanwhile some trees holding visually defect signs were proved to be intact after carrying the tomography images (up to 10 from 53). It is concluded that the visual tree defect inspection is not satisfactory for saving or omitting the individual and these kinds of decision makings must be supported by the methods showing the hidden discontinuities.
Physics and Mechanical Wood
mostafa kohantorabi; Mehran Roohnia; Shadabeh Fathi
Abstract
In this study, 10 samples of beech wood, without apparent defect, with dimensions of 360 × 16 × 16 cm (length × radial × tangential) were selected, and after being exposed to variable temperature (60, 80, 100, 120, 140, 160, and 180°C) and moisture ...
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In this study, 10 samples of beech wood, without apparent defect, with dimensions of 360 × 16 × 16 cm (length × radial × tangential) were selected, and after being exposed to variable temperature (60, 80, 100, 120, 140, 160, and 180°C) and moisture content conditions (moisture content in conditions of: saturated with water (EMC=35±5%), equilibrium moisture content exposed to air (EMC=19±5%), and conditioning moisture content in a climatic chamber (EMC=12±2%), they underwent free flexural vibration test in two longitudinal-tangential and longitudinal-radial planes, and some of the physical, mechanical, and acoustical properties in both planes were investigated. The results showed that the correlation coefficient of the first three modes of flexural vibration in both planes under climatic chamber had a similar situation, but when the samples were in the water-saturated condition, they showed an adverse behavior in each plane. The effect of increasing the temperature above 100°C caused stresses resulting from shrinkage leading to the development of micro-cracks and reduction in the modulus of elasticity of cell walls and ultimately reduction in wave propagation ability of wood, thus increase in the damping vibration values in both longitudinal-tangential and longitudinal-radial planes of the samples. Also, the concurrent changes in modulus of elasticity and damping vibration in both vibration planes are a desirable indicator for monitoring the process from the primary logging process stages to processes such as wood drying and heat treatment.
Physics and Mechanical Wood
Ehsan Haji rafiriha; Mehran Roohnia; Ahmad Jahan latibari; Ajang Tajidini
Abstract
The effect of lamination and adhesive coverage rate in layered products made from Poplar wood was studied The effect of lamination and adhesive coverage rate in layered products made from Poplar wood was studied by non-destructive free vibration test. 120 samples with nominal dimensions of 2.5×2.5×45 ...
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The effect of lamination and adhesive coverage rate in layered products made from Poplar wood was studied The effect of lamination and adhesive coverage rate in layered products made from Poplar wood was studied by non-destructive free vibration test. 120 samples with nominal dimensions of 2.5×2.5×45 cm without any obvious deficiencies were selected and free flexural vibration in free-free bars were performed for testing them. Samples were longitudinal cut in three thinner tangential layers and jointed together again using Poly Vinyl Acetate glue. The specimens were divided into four groups according to adhesive coverage rates, which one group was fully glued and 3 groups were carrying some glue deficiencies in different rates. Manipulated samples were tried again in above mentioned test. Results indicated that shear moduli compare to modulus of elasticity is a more sensitive parameter to evaluate glue efficiency in laminated beams but concerns remained due to blind points in flexural vibration nondestructive method.
Mohammad reza Ghaznavi; Mehran Rohnia; Abdolsaber Yaghmaeipour
Abstract
The possibility of estimating some acoustical properties of particleboard panels such as "Acoustical coefficient" and "Acoustical Converting efficiency" using vibrational non-destructive techniques was investigated. Particleboard plates with the dimensions of 50×50, 100×50 and 150×50 ...
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The possibility of estimating some acoustical properties of particleboard panels such as "Acoustical coefficient" and "Acoustical Converting efficiency" using vibrational non-destructive techniques was investigated. Particleboard plates with the dimensions of 50×50, 100×50 and 150×50 were used. For each plate, three replicated samples were prepared and after conditioning and the measurement of weight and dimensions, the flexural vibration test was performed on plate free-free test. In order to be ensured of the accuracy of the test, panels were converted to beams with the dimensions of 500×50×16 mm and then the same test was repeated on these samples. The results obtained from flexural vibration test of plates and beams were compared. The results indicated that it is possible to evaluate the Acoustic Coefficient and Acoustical Converting Efficiency factors with adequate accuracy using the testing method used in this study.
Amir Mollahassani; Azhang Tajdini; Mehran Roohnia; Amir Tavakkoli
Abstract
The demand for the import of lumber as one of the most important imported sawnwood inIranduring the period of 1984 to 2009 is empirically analyzed using anOrdinary Least Squaremodel (OLS). Prior to estimation, Augmented Dickey Fuller (ADF) and Philips-Perron tests were applied to investigate the stationary ...
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The demand for the import of lumber as one of the most important imported sawnwood inIranduring the period of 1984 to 2009 is empirically analyzed using anOrdinary Least Squaremodel (OLS). Prior to estimation, Augmented Dickey Fuller (ADF) and Philips-Perron tests were applied to investigate the stationary character of the data. Also, to test the presence of Serial Autocorrelation in the error of the regression model Breusch-Godfrey test is used. The presence of a long-run relationship between demand for lumber import and the factors effective on it was measured by Engle –Granger and Johansen- Julius Cointegration tests and finally the causal relation in short-run was analyzed by the causality test of Granger. The results indicated that the nominal exchange rate and domestic production quantity variables imparts adverse impact and GDP and the export petroleum income impose positive impact on demand for import of lumber. Also, the results showed that there exist a long –run equilibrium relationship between lumber imports inIranand the selected macroeconomic and market variables. We find that there is a one-side causal relation from the mentioned explanatory variables to the dependence variable.
Sina Modirahmati; Ahmad Jahan Latibari; Amir Nourbakhsh; Mehran Roohnia; Mansor Minaei
Abstract
The impact of nanoclay addition on the properties of polypropylene/ OCC fibers/ nanoclay Composite was investigated. Composites were prepared using 67% polypropylene, 30% OCC fiber, 3% MAPP and three dosages (2.5, 5, 7.5% based on total weight of PP/OCC/MAPP) of nanoclay. Premix- ...
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The impact of nanoclay addition on the properties of polypropylene/ OCC fibers/ nanoclay Composite was investigated. Composites were prepared using 67% polypropylene, 30% OCC fiber, 3% MAPP and three dosages (2.5, 5, 7.5% based on total weight of PP/OCC/MAPP) of nanoclay. Premix- melting of nanoclay and polypropylene was used to add nanoclay to the composite mixture. Pre-mixed nanoclay/ polypropylene was melt-mixed with OCC fibers and MAPP and then test samples were made using this compound. The results revealed that addition of nanoclay to polypropylene/OCC fiber composite reduced flexural strength , tensile strength and notched Izod impact strength, but the flexural modulus and tensile modulus of final composite were improved significantly. The influence of nanoclay addition on flexural strength and tensile modulus of composite was statistically significant at 99% level whereas its effect on tensile strength was statistically significant at 95%. However, the effect of nanoclay on both flexural modulus of elasticity and impact strength was not statistically significant. The addition of nanoclay to the composite reduces the bonding between polypropylene and OCC fibers. In the case of notched Izod strength, nanoclay particles generated stress concentration point within the composite structure initiating easier failure. Water absorption after 2 and 24 hours immersion was reduced.
Sasan َAbangah; Ahmad Jahan Latibari; Seyad Javad Sepideh dam; Mehran Roohnia; Mohammad ali Hossein
Abstract
The influence of reinforcing fibers (old corrugated container fibers called OCC) and addition of foaming agents (Azodicarbinamide and sodium bicarbonate) on density, strength properties and dimensional stability of OCC fiber/polypropylene composite were investigated. Conten of reinforcing fibers constant ...
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The influence of reinforcing fibers (old corrugated container fibers called OCC) and addition of foaming agents (Azodicarbinamide and sodium bicarbonate) on density, strength properties and dimensional stability of OCC fiber/polypropylene composite were investigated. Conten of reinforcing fibers constant at 20% and the content of either foaming agent varied as 3, 5 and 7%. Strength properties including MOR, MOE, maximum tensile strength and modulus as well as izod impact strength were measured. Water absorption after 2 and 24 hours soaking in distilled water at 23±2 ºC were measured. Foaming agent decomposition caused some chemical residues in composite and the diffusion and penetration of polymer into the fibers structure led to increase in the density from 839.2 kg/m3 for pure polypropylene to 919.2 - 947.9kg/m3 for the composite, MOR and MOE also increased by the addition of foaming agent and the reinforcing fiber. The effect of 5 or 7% sodium bicarbonate was statistically significant and it improved the properties of the composite. Similar results were obtained for tensile strength and the modulus. Reinforcing fibers and foaming agent caused higher impact strength of the composite. Water absorption of the composites was higher than pure polypropylene.
Vahid reza ُSafdari; Behzad Shabani; Seyyed Khalil Hosseinihashemi; Mehran Roohnia; Vilma Bayamzadeh
Abstract
Air pollutantion in particular pollutants from automobile exhaust can affect anatomical and morphological characteristics of woods. In order to investigate the impact of this factor, Pinus eldarica trees of Chitgar park in Tehran, the area which is extended from south to crowded highway (polluted ...
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Air pollutantion in particular pollutants from automobile exhaust can affect anatomical and morphological characteristics of woods. In order to investigate the impact of this factor, Pinus eldarica trees of Chitgar park in Tehran, the area which is extended from south to crowded highway (polluted site) and in north to Alborz Mountain (unpolluted site) and the middle part (semi-polluted site) were sampled by increment borer. After cross-dating, the tree rings of recent 5 years were separated from the old rings. Then anatomical characteristics of cross section, including transition between early and latewood, tangential thickness of last formed latewood tracheides, frequency of ray and resin ducts and morphological characteristics of tracheids in three zones and in the same rings were studied. Results indicated that the ring width pattern of Pinus eldarica in three zones is somehow the same. The frequency of resin duct and rays and false rings in 2005 and 2006 in the polluted and semi-polluted site were higher compare to the unpolluted site. Fiber length, wall thickness (2d) and lumen size of trees of unpolluted site were more than the other two sites (Polluted and Semi-polluted). In general, it could be concluded that air pollution impact on tree ring width can reduce wood quality as well.
Physics and Mechanical Wood
Jafar Eskandari; Amir sohil Pirayeshfar; Mohammad mehdi Jalili; Sayed yahya Mosavi; Mehran Rohnia
Abstract
In this study, three composites (Carbon fiber- Polyester resin, Glass fiber-Polyester resin and Hemp fiber-Polyester resin) are designed as a substitute for the wood in music instruments and their acoustic properties such as elastic modulus, acoustic coefficient, and acoustic coefficient efficiency are ...
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In this study, three composites (Carbon fiber- Polyester resin, Glass fiber-Polyester resin and Hemp fiber-Polyester resin) are designed as a substitute for the wood in music instruments and their acoustic properties such as elastic modulus, acoustic coefficient, and acoustic coefficient efficiency are investigated. For better evaluation of the results, two wood specimens from Cupressus arizonica and Morus Alba trees (which are using in many acoustic applications) were chosen and analyzed as control samples. The results show that the resultant composites possess essential acoustic and vibrational properties so that the result for Carbon fiber-Polyester composite exhibits tremendous acoustic properties than wood samples did. In this paper, the water absorption of resultant composites and wood samples were also measured. The results demonstrate that composites specimens could resist against humidity much better than wood samples.
Management and Economics wood
Amir Tavakkoli; Ajang Tajdini; Mehran Roohnia; Ahmad Jahan latibari
Abstract
Corrugated board is considered as a valuable community for packaging at both international and domestic markets. Therefore for the development of corrugated board industry in Iran and to understand the variation in demand for this product, it's necessary to identify the consumption ...
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Corrugated board is considered as a valuable community for packaging at both international and domestic markets. Therefore for the development of corrugated board industry in Iran and to understand the variation in demand for this product, it's necessary to identify the consumption and production patterns as well as the most important and effective variables influencing it's status. Then the demand & supply for corrugated board can be forecasted. In this study, the dynamic econometric model has been used to demonstrate simultaneous relationship between supply and demand. Coefficients of the model were estimated using 3sls method with the time series data from 1981 to 2007. The results indicated that in the demand function, intercept, price, GNP in previous period, population, CPI, industrial added value(Iav), production index of large-scale industries(PILSI) and the war dummy variables are significant at 0.05 level. In the supply function, intercept, production quantity in previous period, inflation rate, corrugated board price-raw material price ratio in previous period, import quantity in previous period, cost price all in previous period and subsidy dummy variables are significant at 0.05 level. Results indicate that the mentioned variables influence consumption and production, simultaneously. The results of projection also demonstrate that corrugated board production & consumption will increase into 2012.
Management and Economics wood
Ajang Tajdini; Mehran Roohnia
Abstract
Total and per capita consumption of fluting paper was calculated using data and information from production, import and export for last decades. Then based on the fact that consumption of paper and paper products is a function of both per capita consumption and population of any country, regression analysis ...
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Total and per capita consumption of fluting paper was calculated using data and information from production, import and export for last decades. Then based on the fact that consumption of paper and paper products is a function of both per capita consumption and population of any country, regression analysis was used to predict per capita consumption for the period of 1994-2003, total consumption for the period of 2006-2011 as well as the year 2021. Finally based on the calculated consumption of different papers and considering the present and future capacities for paper production, the shortage of paper was derived. Results showed that the fluting paper consumption for the year 2021, will reach 290000 tons which causes 200,000 tons of shortage per year. This shortage will require that almost 70% consumption need to be fulfilled by import.
Pulp and paper
Mehran Roohnia; Ahmad Jahan latibari; Sayed Zyae Aldin Hosseini
Abstract
In this research, pulping of rinds from sunflower seeds by soda process is studied. Fiber length was 0.89 millimeters and its chemical content, contained 40.5% Cellulose, 30.5% Lignin, 3.33% Ash and 1.93% Extractives. Conditions of Soda process were three different soda consummations of (Chemical charge) ...
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In this research, pulping of rinds from sunflower seeds by soda process is studied. Fiber length was 0.89 millimeters and its chemical content, contained 40.5% Cellulose, 30.5% Lignin, 3.33% Ash and 1.93% Extractives. Conditions of Soda process were three different soda consummations of (Chemical charge) 14%, 16% and 18%. Liquor on rinds ratio, was equal to 6, and period of digestion was 30 minutes. Yield and Kappa number on the best choice of conditions of pulping (165 degree of centigrade temperature and 16% soda consumption) were measured respectively 55.7% and 74.96.Using PFImill, four kinds of pulps with four different free nesses were produced from the proper Pulp and were changed to hand sheets. Study on mechanical strength of hand sheets showed that beating has no effect on tear strength from 30 to 40 SR and it reduces this strength after more beating. Practically, no effect was observed on burst strength and breaking length during beating from 30SR to 60SR. This lignocellulose, agricultural residue is a cheap by-product in Sunflower-oil producer factories. Some of them is as a food for live-stocks and some is burned as a source of energy. Because of this, using rind from sunflower seeds in Paper and other cellulosic industries can be useful.
