جستجوی مقالات مرتبط با کلیدواژه « physical properties » در نشریات گروه « صنایع چوب و کاغذ »

Background and goal: 

walnut tree (Juglans regia L.) are cultivated in many countries in Asia, Europe and United States. This tree has high resistance with beautiful pattern and are used in furniture industry, building panels, flooring and covering. Iran are ranked third in the world in the production of walnut fruit after China and US. Thus, with considering high production of this tree in Iran and its diverse application in different industries, a comprehensive studding for physical and mechanical properties of this species in different regions of Iran seems necessary.

Walnut tree (Juglands regia L.) from two different regions, one from northeast (Mashhad) and the other from northwest (Mako) of Iran was selected for this study. Three trees from each region were selected randomly and cut with almost with the same diameter for physical and mechanical experiments. Samples also were cut from 2-4 meter from the ground. ISO 3129 and ASTM (D143-14) were used for doing physical and mechanical experiments respectively and at the humidity of 12%. Statistical analysis of data was performed using Graphpad prism version 8 and t-Test was performed for significant difference of data.

The average dry density of both Mashhad and Mako walnut wood was 0.625 and 0.579 g/cm3 respectively. There were a significant difference for both tangential shrinkage with values of 9.77 and 8.78 and volumetric shrinkage with measurement of 16.26 and 15.42 in Mashhad and Mako respectively. However, there was no significant difference for longitudinal and radial shrinkage in both walnut wood of the two regions. Walnut wood cut from Mashhad region showed higher physical and mechanical properties. The results of the mechanical characteristics of walnuts from two regions showed bending strength 100.54 and 87.61N/mm2 and elasticity modulus 10049.59 and 7504.21 N/ mm2for Mashhad and Mako regions respectively which were significant. Results also showed not significant difference for compression parallel to the grain with values of 37.91 and 33.88N/mm2, for shear parallel to the grain with values of 9.15 and 8.95N/mm2, for Tensile strength parallel to the grain with 127.97 and 125.83 N/mm2, for Screw withdrawal strength in tangential values of 4031.01 and 3685.97N and Screw withdrawal strength in radial values of 4218.63 and 3915.03N and impact strength with the values of 27.81 and 25.24KJ/m2 for Mashhad and Mako regions respectively. Results also showed that the density of walnut wood in the two regions of Iran was similar to the those in Italy and eastern Europe but the mechanical properties of walnut tree such as bending strength and elasticity modules measured from Mashhad region was similar to the wone in turkey.

The results showed that the physical and mechanical resistance of walnut wood located in Mashhad is higher than Mako wood, which was attributed to the higher dry density and the difference in weather conditions. Considering the appropriate mechanical resistance of walnut wood from both regions of Iran, this wood can be used in coating and furniture industries, building panels and flooring.

In this study, the effect of changes in pH and molar ratio on the properties of melamine formaldehyde resin for impregnating decorative paper was investigated. The physical properties of the resin such as free formaldehyde, resin shelf life, and the percentage of resin solids contents were investigated in different conditions Also, the molecular structures of resin were studied using FTIR spectroscopy and thermal analysis of resins through TGA. The results showed that a higher pH improved the characteristics of the resin and melamine coating, while increasing the molar ratio of formaldehyde to melamine weakened the characteristics of the resin and coating. In addition, the results showed that the changes observed in the resin caused by The variables of molar ratio and pH have no significant effect on the thermal properties of the resin.

This research was conducted with the aim of investigating the effect of two-layer coating of nano-polyurethane and nano-clay on the mechanical and physical properties of packaging cardboard with brown layer. For this purpose, brown layer cardboard with grammage of 127 was prepared and tested. To coat the surface of the cardboard, it was first coated with nano-polyurethane and sprayed by a coating nozzle. Then the surface of the brown layer cardboard was covered with nano-clay to improve the performance of the coating material of the first treatment. Nano-clay coating was performed by a laboratory coating machine called barcoter. The coated cardboards were restrained and dried in the room for one day to stabilize the coating material on their surface. Then the samples were placed inside the freezer for 2 and 4 months and their properties were measured. The results showed that coating reduced water absorption. In the coated and frozen samples, an increase in thickness, smoothness of the surface and a decrease in water absorption and resistance properties compared to non-frozen control samples have been observed. Double coated samples showed very few pores. The thickness, smoothness of the surface and resistance to tearing in the machine cross direction of the double coated brown cardboard showed an increase of 13.7%, 75% and 3.8%, respectively, compared to the control sample. water absorption, resistance to bursting, resistance to tearing in the machine direction, resistance to tensile in the machine direction, resistance to tensile in the cross machine direction, resistance to ring crush test in the machine direction and resistance to ring crush test in the cross machine direction of the double-coated brown layer cardboard compared to the control sample, showed 107.20, 1.5, 34.3, 25.4, 24.3, and 4.7 percent decrease respectively.

The walnut tree is one of the most important species in Europe, Asia and Iran, which is used in various industries such as furniture, veneer, and construction due to its high resistance and beauty. In this research, walnut trees from two different geographic locations, one from the forests in the north of Iran (Noor) and the other in the west of Iran (Shahrkord), were selected. We studied physical properties including dry density, basic density, shrinkage, and mechanical properties including bending strength, modulus of elasticity, compression parallel to the grain, shear, tensile parallel and perpendicular to the grain, tangential and radial screw withdrawal strength and toughness. In this research, standards 3129 and ASTM D143-14 were used to perform physical and mechanical tests, respectively. The moisture content of all samples during mechanical tests was 12%. The average dry density of Noor and Shahrekord walnuts was 0.61 and 0.57 (g/cm3) respectively. The results of variance analysis showed that the characteristics and physical resistances of these two species were not significantly different except for dry density, radial, tangential and volumetric shrinkages. However, due to the higher density of Noor species, it showed higher mechanical resistance compared to the Shahrekord species.

Since the information related to heat treatment of wood by industrial method is mainly related to coniferous wood, this research seeks to investigate the physical and mechanical properties of birch wood after heat treatment in the industrial furnace. For this purpose, birch wood according to the instructions of the Thermowood Association of Finland for the production of Class D Thermowood was used. Water absorption, dry and critical density and 12% Moisture, shrinkage, swelling, and color components (L*a*b*), anatomical features and wettability test, mechanical properties of wooden samples including MOE, MOR, impact strength and compression strength parallel to gain were evaluated and compared to the control samples. The results showed that the color of thermos-treated wood has become significantly darker than the control one. In birch wood, the moisture content of heat-treated wood showed a decrease of 117.7% compared with the control sample. The critical density of heat-treated wood showed an increase of 7.3% compared with the control sample. The dry density of the sample after heat treatment showed a decrease of 0.6% compared with the control sample. The density after heat treatment showed an increase of 2.3% compared with the control sample. The shrinkage and swelling of the thermos-treated sample showed a decrease of 100.5% and 115.4%, respectively, compared with the control sample. It was more difficult to prepare the section of the heat-treated wood than the control sample, while destruction of vessels, fibers, and rays was visible. The modulus of elasticity, modulus of rupture, impact strength and compression strength parallel to gain of the heat-treated samples showed a decrease of 3.22, 3.4, 147.97 and 2.95%, respectively, compared with the control sample.

In this research, the effect of chemical treatment of palm particles with alkoxysilan on the mechanical and physical properties of wood-cement particleboard was investigated. For this purpose, palm particles were chemically treated with 7.5% and 15% alkoxysilane to make wood cement particleboard with a weight ratio of 30 to 70 and in the presence of 5% calcium chloride (based on the dry weight of cement). Test samples of mechanical (bending strength and modulus of elasticity and internal bonding) and physical (water absorption and thickness swelling) were prepared in three levels of control, 7.5% and 15% alkoxysilane according to the European standard. The results showed that the chemical treatment of palm particles with alkoxysilane had a positive effect on the mechanical and physical properties of wood cement particleboards, so that with the increase of alkoxysilane up to 15%, the maximum mechanical resistance and the lowest physical properties were obtained. The significant increase in the resistance and physical properties of the boards resulting from the addition of 15% alkoxy silane can be attributed to the reaction between the hydroxyl groups of the palm constituents with the active groups of alkoxysilane and greater cohesion between the palm particles and cement. In order to describe the effectiveness of chemical treatment, discriminate analyzes such as infrared spectroscopy and scanning electron microscopy were used. The results of Fourier transform infrared show an increase in the intensity of the peaks related to Si-O bonds in the samples modified with alkoxysilane and as a result of the chemical modification of palm particles. Also, the uniform and coherent structure of the scanning electron microscope of wood cement particleboard modified with silane agent has indicated the chemical reaction between palm particles, alkoxysilane and cement, and as a result, more compatibility and entanglement between modified palm particles and cement.

The properties of wood composite products are due to the control variables of factory machines. Identifying these sensitive places is of particular importance, because it allows the operator to be able to adjust the production line and product quality in a completely engineered way. Also, it allows operator to have a more detailed study of material and process behavior. Factory available data are including variables of moisture content of chips, chips density, density Mat, material temperature The amount of glue used in percent, the amount of glue used in kilograms, fiber moisture and press speed, and also properties of density, flexural modulus, modulus of elasticity, internal bonding, board moisture and thickness swelling. The effect of input variables on each of the properties of fiberboard was determined by artificial neural network method. The results show that all of the input variables have affected on the output properties of fiberboard and the order in which the influential variables are depends on the type of properties. The effect of variables such as density Mat is almost greater than other variables. Some input variables, such as the, the amount of glue used in kilograms, have less effect on the properties of fiberboard with medium density, and this variable is considered constant in the production line of some factories. The high correlation between the prediction value and the actual value of the output and its low mean absolute percent error indicates the high validity of the prediction that have a high value of 0.9 and less than 9%, respectively.

Pinus taeda is one of the fastest growing species with high wood production capacity. Due to the afforestation of this species in Gilan province, which can be a good alternative to some other imported fast growing species.The aim of this study is to investigate of possibility of using Pinus taeda wood instead of four common species of poplar (Pulpous sp.), Tehran pine (Pinus eldarica), Abies (Abies sp.) and Sasna (Pinus sylvestris). For this purpose, physical and mechanical properties of five species were measured and statistical analyzes were performed. The results showed that Pinus taeda has lower density, water absorption and volumetric swelling than the other four species. Regarding mechanical properties, the results showed that Pinus taeda, with its lower density than other species, has moderate mechanical strength. The ability of Screw and Nail Withdrawal Strengths for Pinus taeda in parallel and perpendicular directions to the grains was not much different from other species. Also, the resistance of mortise- tenon and dowel joints for Pinus taeda was higher than other species and there was a significant difference with them. According to the obtained results, Pinus taeda wood with low density and suitable mechanical properties can be a good alternative for some imported fast-growing species and is also recommended for afforestation and wood cultivation in different parts of the country.

The study of wood characteristics of a plant species at different altitudes has always been considered by researchers in this field because altitude is one of the most important and influential options on climatic factors (temperature, rainfall, sunlight and relative humidity) in an area. The aim of this study is to obtain accurate knowledge of changes in biometric, physical and mechanical properties of Caucasian alder(Alnus subcordata) species in different altitudes of northern Iran. In this study, three habitat altitudes above sea level in Savadkuh region, Talar basin in Mazandaran province, with the names of Shalimak series (1400 meters height), Miyana series (1000 meters height) and Miyan Darreh series (500 meters height) were selected. From each height, three trees and a total of 9 trees were cut and from each tree, a disk with a thickness of 10 cm and a sample with a length of 150 cm from the diameter equal to the chest upwards were prepared. After initial preparation, the samples were measured according to the standard to evaluate different properties and were evaluated and analyzed. The results showed that altitude is one of the effective factors in changing the properties of the studied properties, so that with increasing altitude, the average fiber length, fiber diameter, cavity thickness and thickness of two walls decrease and the average specific gravity and volume shrinkage, Modulus of elasticity, modulus of rupture, compreession parallel to grain, cleavage, nail withdrawal resistance in cross-section and tangential, radial and cross-sectional hardness increased. The mechanical index of Caucasian alder wood in all three elevations was in the middle range,

Borons and copper-based compounds are compounds used as pesticides and fungicides. One of the main problems of these compounds is that they easily be washed. Therefore, the main purpose of this study is to stabilize and reduce the leaching of protective materials using the encapsulation method. The encapsulation method of pesticides (boric acid and Bordeaux) was performed by natural chitosan polymer via electrospinning method and the compounds were used to treat poplar wood layers and make plywood. To evaluate the performance of the final product, physical tests (density, thickness swelling and water absorption), Fourier transform infrared spectroscopy and fungal tests were performed. The results showed that despite the low load of boric acid and pesticide, the performance of the layers was effective against fungal degradation. However, after severe leaching, their performance was reduced. The layers treated with the encapsulated pesticides retain their function as a pesticide against the fungus after washing. In general, the results showed that the technique of encapsulating pesticides can significantly reduce their leaching and on the other hand leads to maintain the function of pesticides.

In the current research, enzymatic modification of OCC pulp with Bacillus sp. amylase was evaluated. Amylase was added at different levels of 0.5, 0.1, 0.2 and 0.3% (based on oven-dried weight of recycled paper) to OCC pulp under constant conditions included consistency of 10%, temperature of 50°C, time duration of 1 hour, and at a pH range of 6.9-7. To neutralize the residual enzyme, hydrogen peroxide 0.05% (based on oven-dried weight of pulp) was applied. The refining of pre-treated OCC pulp with different levels of amylase was done at the constant revolution of 2000. The dewatering and physical properties of amylase pre-treated OCC pulps as compared to control pulp (non-treated pulp with enzyme) for two refined and unrefined conditions were evaluated. Obtained results showed that amylase pre-treatment improved pulp freeness by 11-22% compared with the control sample. The highest freeness (600 ml, CSF) was achieved with 0.2% amylase. Refining of both amylase pre-treated OCC pulp and the control sample reduced the pulp freeness, but dewatering capability increased with an increase in amylase usage. The use of Amylase resulted in a paper with slightly higher caliper, higher bulk, but similar air resistance, compared with control run. An increase in amylase usage from 0.5% to 0.3% along with refining decreased caliper and bulk and increased air resistance of paper. Also, the results of the evaluation of different times of amylase treatment of unrefined OCC pulp (at a constant concentration of 0.1%) on a caliper, bulk as well as air resistance indicated that the duration of 90 minutes was the optimal time. In general, the combined treatment of amylase (0.05-0.1%) and PFI refining (at the constant revolution of 2000) indicated the pulps with better quality in terms of dewatering and physical characteristics in comparison with control OCC pulp.

This study aims to use zeolite as a retarder of particleboards from sugarcane pulp (bagasse). In this study, mechanical properties, physical properties, fire resistance and CIE L * a * b * colorimetric test were investigated. The results of this study showed that the use of zeolite led to an increase in flexural strength, modulus of elasticity and impact resistance of the resulting particleboards. However, the internal adhesion of the resulting particleboard decreased. In addition, the use of zeolite as a flame retardant increased fire resistance. The results of physical properties also showed that zeolite reduced water absorption and thickness swelling in 2 hours of immersion. While water uptake and thickness swelling increased during 24 hours of immersion. The results showed that zeolite caused color change with increasing Δl and finally increased the whiteness and brightness of the surface of the samples. Zeolite reduced the combustion parameters, reduced the mass due to burn and the amount of carbonized surface and significantly increased the ignition time while drastically reduces flame retention and weight loss. In general, according to the measured parameters, the addition of zeolite can be considered as a slowing treatment.

Wood modification with cell wall modifiers change the practical properties of wood. Likely, changing the modification conditions with chemicals by different reactivity has a more favorable effect on wood properties. This research was conducted to determine the effect of cell wall modification with glycidyl methacrylate (GMA) and maleic anhydride (MA) on practical properties of wood polymer composite. Test samples were divided into ten groups; control, impregnated with styrene, and combined modification of cell wall (GMA and MA) at four concentrations of 10, 20, 30 and 40%/styrene. Cell wall modification, with increase in weight and conversion rate, improved hydrophobicity and dimensional stability of specimens which for GMA was more than MA. With increasing of the GMA concentration from 30 to 40% and cell wall bulking, cracks probably formed in the cell wall that increased water uptake and dimensional changes. The presence of monomer along with modification, by reducing the polarity of wood, uniform distribution of monomer in wood, and improving the adhesion between polymer and wood, increased the mechanical properties of composites, which showed the highest improvement in GMA/styrene. Modification with MA and GMA prevented the fungi mycelium development through reducing hydroxyl groups, changing the hollocellulose structure, and the presence of polymer as a physical barrier. The effect of GMA combined with monomer created more improvement on biological resistance up to 20% concentration, and by increasing the concentration to 40%, it did not show a significant difference with MA. The mechanical properties improvement can be attributed to the formation of polymers with excellent performance and the effect of modification on the cell walls. In most properties, the effect of GMA up to 20% concentration was more than MA, but with increasing concentration and possibly the appearance of cracks in the cell wall, the efficiency of MA modification was higher than GMA.

Wood modification with epoxy compounds, such as glycidyl methacrylate, could result in less moisture absorption and dimensional changes due to reduction in the number of hydroxyl groups and cell wall bulking. It is likely that change in the conditions of modification reaction would have a favorable effect on the physical properties by increasing the hydroxyl group’s substitution. To determine the optimal modification condition with glycidyl methacrylate, samples were modified at different concentrations (10, 20 and 30%), temperatures (90, 120 and 150°C) and times (8, 16 and 24 hours). Based on spectrum analysis, decrease of hydroxyl groups intensity and increase of carbonyl groups intensity confirmed cell wall modification with glycidyl methacrylate. Cell wall bulking and hydrophobing due to modification led to a reduction in porosity and free water adsorption. According to the results of soaking-drying cyclic test, increase of glycidyl methacrylate concentration led to the reaction with more number of hydroxyl groups, and higher temperature and longer duration of modification reaction also led to an increase in the reactivity of the epoxy groups with the wood cell wall. The higher temperature of reaction led to maintenance of weight gain due to modification, via formation of a more stable structure against hydrolysis. Scanning electron microscopic images confirmed cell wall swelling and polymerization of glycidyl methacrylate in wood cavities. In a general conclusion, it can be claimed that the concentration of 20%, the temperature of 150°C and the time of 16 hours are the optimal conditions for modification with glycidyl methacrylate.

Surface modification with natural modifiers containing chemical bonding agents including rosin maleic can improve the physical properties of wood by reducing the number of hydroxyl groups. It is likely that an increase of temperature or the presence of a catalyst will have a more desirable effect on the physical properties of the wood by improving the hydroxyl group’s substitution of the wood cell wall. This study was conducted to investigate the effect of different temperature levels and the presence of aluminum chloride catalyst for applying surface modification with Rosin Maleic, and evaluating the efficiency of the modification on the physical properties of Spruce wood. The samples were immersed in a rosin maleic solution with a concentration of 40% by weight/ volume (in toluene/xylene solvent) for 24 hours, and were heated for determine the effect of temperature, catalyst and leaching, under two temperature levels of 60°C, with and without catalyst, and 140°C, for 4 hours. According to the results, modification by reducing the hydroxyl groups (based on the infrared spectrums), improved hydrophobicity and dimensional stability of the treated samples. At the end of water immersion period, the higher temperature of reaction with formation a more stable structure against hydrolysis, led to maintenance the weight percent gain of modification. Increasing the modification reaction temperature from 60°C to 140°C create a significant difference in the measured properties, but the presence of the catalyst in the modification at 60°C reduced this difference and formed more stable structures. In a general conclusion, it can be claimed that the use of aluminum chloride as a catalyst in modification with rosin maleic, makes possible applying surface modification at ambient temperature, by forming a more stable structure against hydrolysis.

In this study, the utilization of fibers recycled from MDF wastes and waste papers for manufacturing fiberboards was investigated. The proportion of waste paper to recycled fibers from MDF wastes was 70/30 and 50/50. Also the effect of utilization of poly vinyl acetate adhesive on properties of boards was investigated. Boards were manufactured at density of 0.3 g/cm3 and dimension of 30×30×1.2cm. Practical properties of boards including thickness swelling, bending strength, modulus of elasticity and internal bonding were measured. The results showed that the utilization of adhesive can improve all of board properties. Change in proportion of recycled fibers to waste paper had different influences on various properties of manufactured fiberboards. The proportion of 70/30 of waste paper to recycled fibers from MDF wastes led to improving bending strength and modulus of elasticity of fiberboards, while the manufactured boards from proportion of 50/50 had better results about thickness swelling and internal bonding. Overall, it can be concluded that recycled fibers from MDF wastes mixed with waste paper can successfully utilize in producing fiberboards.

For investigation on the effect of densification on the physical and mechanical properties of the chemically and thermally modified poplar wood (Populus deltoides), thermal modification at 170°C, chemical modification with glutaraldehyde, and compression at three levels of 10, 25, and 40% at the hot pressing time of 2h were carried out. With increasing compression ratio from 25 to 40%, the density of thermally and chemically modified samples increased by 13% and 8%, respectively. Spring back and moisture absorption of the thermally modified/compressed samples was more than chemically modified/compressed ones. Water absorption and thickness swelling for 10% compression ratio were more than the chemical and thermal control samples but significantly decreased with increasing compression ratio. The mechanical properties of both thermally and chemically modified samples were improved with increasing compression ratio. From 25 to 40% compression, improvement of bending modulus for both modified samples were more than 10 to 25%, which was more significant for the thermally modified samples. Bending strength was also improved with increasing compression ratio, but the intensity of improvement decreased by 40% compression. Increasing of compression ratio also led to a significant improvement of the compression strength parallel to grain and hardness, which was more obvious for glutaraldehyde modified specimens than the thermally modified ones.

The aim of this investigation was concentrated on the possibilty of untilizing corn cops residues in the production of particleboard. Two press temperatures of 170 and 180 oC, and four ratios of corn cop/poplar wood particles (100/0, 75/25, 50/50 and 25/75) in the corn layer of the boards and 100% poplar wood particles in the surface layer were used. A combination of 16 treatments were reached and three laboratory boards for each treatment were made. Physical and mechanical properties of the boards were measured and statistically analyzed. The grouping of the averages were based on duncan multiple range test. The results indicated that the influence of the press temperature on both modulus of rupture and modulus of elasticity was statistically significante and boards produced applying 170 oC reached higher values. As the ratio of the corn cop particles in the particle mixture in core layer increased, both modulus of rupture and internal bonding deteriorated and the highest value were measured at 50/50 ratio of the particle in the core layer. The Boards which produced applying higher press temperature exhibited hgiher rate of thickness swelling . Lower ratios of the corn cop particle in the mixture of particles in the core layer improved the properties of the boards. So that the ratio of 50/50/ and 25/75 produced lower thickness swelling. The results of this research revealed that eventhough boards produced using corn cop particles did not produce comparable properties to the boards based on poplar particles, but it can be concluded that if 50/50 ratio of particles, press temperature of 170 oC is used for board making, the mechanical properties of the produced boards will meet the requirement of DIN specifications.

In this study, the composition of bagasse composite was investigated using different amounts of bagasse particles. Bagasse and cement particles are manufactured at levels (5, 10 and 15%) and percentage of calcium chloride as cement accelerating additive at two levels (3 and 2%) based on cement dry weight. Then, the mixture was poured into a mold measuring 15 8 18 8 8 cm and the excess water was removed from the bottom of the mold and initially weighed 10 kg on the specimens. The specimens were removed from the mold after 48 hours and kept in a glass saturated room at 90% humidity for 14 days and then finally dried in a laboratory environment. The bending strength and physical properties tests were performed on the specimens. The results showed that bagasse particles had a significant effect on bending strength and other physical properties. The bending strength was highest in boards made with 10% bagasse particles.

This research was conducted to compare the effect of tetraethoxy silane and triethoxy vinyl silane on chemical structure and physical properties of poplar wood. Test samples were divided into control, modified with silane compounds, vinyl silane / benzoyl peroxide initiator, and combined of silane/ benzoyl peroxide. Modifier resulted in change of chemical structure, increase of density and bulk of wood samples. Weight gain of triethoxy vinyl silane modified samples was higher than tetraethoxy silane modified ones, which was more significant in presence of initiator. The initiator significantly reduced water absorption and dimensional changes in modification with silane. At the end of soaking-drying test, weight loss and bulking coefficient of tetraethoxy silane modification was higher than triethoxy vinyl silane. The lowest loss of weight and bulk were calculated for triethoxy vinyl silane /benzoyl peroxide and combined modified samples. In the first cycle, water absorption of the triethoxy vinyl silane modified samples was more than tetraoxysilane, and from second cycle, this trend was reverse. Initiator with polymerization of triethoxy vinyl silane more significantly decreased water absorption and volume swelling