جستجوی مقالات مرتبط با کلیدواژه « internal bonding » در نشریات گروه « صنایع چوب و کاغذ »

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.

In this study, the effect of nano-wollastonite on physical, mechanical and morphological properties of composites made of bagasse and gypsum was investigated. The mixing ratio of sugarcane to gypsum pulp at three levels (80:20, 70: 30 and 40: 60%) and nano-wollastonite at three levels of zero, 3 and 7% were considered as the variables of this study. The thickness of the test boards was 16 mm cake density of all boards was considered to be 1.10 gr/cm3. Then the mechanical and physical properties of the specimens including modulus of rupture, modulus of elasticity, internal bonding, water absorption after 2 and 24 hours immersion and density of boards according to DIN-EN-634 and fire resistance (weight loss percentage) according to ISO 11925 Were measured. In this study, a thermocouple and a flask were used to measure the hydration heat. Microscopic images (SEM) were obtained from the fracture surface of the specimens to investigate the common boundary between bagasse-gypsum and nano-dispersion. The results showed that with increasing bagasse mixing, the modulus of rupture, modulus of elasticity and internal bonding decreased and water absorption and weight loss percentage of boards exposed to fire increased. Application of nano-wollastonite up to 7% improved all mechanical and physical properties of composites. Also, microscopic imaging (SEM) showed that the optimum level of nano-wollastonite can fill vacant voids due to gypsum hydration and create a uniform structure.

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 effect of nano gel wollastonite on physical, mechanical and morphological properties of composites made of bagasse and cement has been investigated. The mixing ratio of bagasse as lignocellulosic material with Portland cement at three levels (15:85, 25: 75 and 35: 65%) and nano-wollastonite at three levels of 0, 3 and 7% were considered as the variables of this study. The cake density of all boards were 1.1 g / cm3 and calcium chloride booster 5% for all treatments were considered as constant factors. Mechanical and physical properties of the specimens include modulus of rupture, modulus of elasticity, internal bonding, thickness swelling after 2 and 24 soaking hours in water and density of boards according to DIN-EN-634 and fire resistance (weight loss percentage) according to standard ISO-11925 were measured. In this study, the hydration temperature of a mixture of cement, bagasse and nano-wollastonite was measured using a thermocouple and flux. Also, microscopic images (SEM) of samples were prepared to investigate the morphological properties of composites and their distribution. The results showed that by increasing the amount of nano-wollastonite, the percentage of weight loss boards decreased, the heat of hydration and the physical and mechanical properties improved. The modulus of rupture, modulus of elasticity, and internal bonding of boards decreased with increasing bagasse content and the maximum value was obtained using 15% bagasse. The results also showed that with increasing bagasse content in boards, there was a significant increase in thickness swelling of boards. Inference from microscopic imaging (SEM) showed that the optimum level of nano-wollastonite can fill the empty holes and create a uniform structure and thus improve the properties of the boards.

The purpose of this study was to investigate the possibility of using tobacco stalk and industrial wood particles in particleboard industry as a waste material that is not consumed and discarded and has a low price, followed by a reduction in production costs from the way of choosing this raw material was of low value. For this purpose, the particles of tobacco stalk and industrial wood particles with different ratios of 0:100, 30:70 and 60:40, using the amount of adhesive used 12% and 14% (based on the dry weight of the wood chips) and the press time of 5 minutes for the construction of the board was considered. Physical and mechanical properties including thickness swelling after 2 and 24 hours immersion in water and bending strength (MOR), modulus of elasticity (MOE) and internal bonding (IB) were measured and all data were statistically analyzed. According to the results of this study, the increase in tobacco stalk particles resulted in increased thickness swelling after 2 and 24 hours immersion in water and reduced bending strength, modulus of elasticity and internal bonding, but all boards had a European standard (EN). Increasing the amount of resin also had a significant effect on all the properties of the boards and improved the properties. In a general conclusion and by comparing the properties of the boards produced with the European standard (EN), showed that using 60% tobacco stalk and 12% urea formaldehyde resin can be produced particleboard with the desired properties. This is a positive result of using tobacco stalk as a type of agricultural residue and, consequently, the prevention of environmental pollution caused by the burning of these compounds.

In this study, fracture toughness and internal bonding of OSB made from Poplar (Populus nigra) was studied. For this aim, ratio of UF to MF (20; 80, 40:60, 60:40 and 80:20), mat moisture (11 and 13), press time (5 and 7 min) and the panel thickness (12 and 16 mm) were chosen as variables. Specimens based on Taguchi design of experiments with the array of L8 (4^1 2^3) were produced and fracture toughness and internal bonding were determined following ASTM E399 and 319 EN respectively. Fracture toughness was determined using stress intensity factor and fracture energy. The result of percentage contribution and the variables ranking showed that the most determining factor on fracture toughness is the ratio of UF to MF. The effect of press time on stress intensity and internal bonding and the effect of panel thickness on fracture energy had the least importance. The highest fracture toughness was belong to OSBs made with UF to MF ratio of 60:40, mat moisture of 11%, press time of 7min and the panel thickness of 12 mm. The highest fracture energy and stress intensity factor was 2944 J/m2 and 0.19 MPa respectively. The optimum treatment was UF to MF ratio of 80:20, mat moisture of 13%, press time of 7min and the panel thickness of 12 mm in light of gaining the highest internal bonding (0.95 MPa).

In this study, phenol was partially substituted with urea to reduce the production cost of phenol formaldehyde resin (PF), and a new resin phenol-urea-formaldehyde (PUF) was synthesized. Different formulations of resin PUF with different molar ratios were made using different methods. The structure of the formulated resins and their coagulation behavior were evaluated with infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC), respectively. FT-IR and DSC analysis indicated the best results for the synthesized PUFB3 which was made from phenol, urea, and formaldehyde with a molar ratio of 1: 0.5: 1.7, respectively, and exhibited a similar methylene structure with PF resin. Then, the formulated resins were applied to produce particleboard. Mechanical properties of the produced particleboards were determined and compared with those of ones which were prepared with PF resin as the control treatment. The findings demonstrated that the substitution of urea increased the dry internal bonding strength and modulus elasticity but reduced the internal binding strength of the produced particleboards following a two-hour immersion into boiling water. The findings revealed that the mechanical properties of the particleboards produced with PUFB3 resin were comparable with the control treatment, and the formulation of phenol, urea, and formaldehyde with the molar ratio of 1: 0.5: 1.7 was selected as the optimum treatment for outdoor condition and under load. In addition, the particleboards produced with PUFD1 resin which was formulated of phenol, urea and formaldehyde with the molar ratio of 1: 0.5: 2.5 exhibited standard properties for application in outdoor conditions without load.

With growth and development of the modern societies and achieve towards industrialization of the countries, Use of the water, one of the major concerns is considered. Optimal usage of water resources, has special position and considerable, that its result is importance of the reuse of rain's water as a reliable source for supply the consumption water. The purpose of this research was, use of rain's water, in composition with urea formaldehyde adhesive, In order to adjust the final concentration of the adhesive. To prevent damage against rain water equipment, the Lagan system was transferred through the canals constructed at Arian sina factory. Then it was treated with the package at the factory. The results of the FT_IR spectrum, obtained from composition adhesive samples with rain's water and ordinary water, showed that the rain's water increased the number of hydrogen bonds in the adhesive. But based on the t test, the difference between Mechanical strength and physical properties of use of rain's water than to the ordinary water was not significant. Qua that the glue combined with rain's water does not have any negative effect on adhesive properties. Therefore, after research, Arian Sina has been saving water consumption by using 14000 liters of water per day, due to the country's limited resources and lack of resources.

The application of corn stalks in the production of oriented strand board (OSB) is investigated. Corn stalks strands were produced in three sizes of 50, 75 and 100 millimeters length and dried to reach 2% moisture content. Oriented strand boards were made using either urea formaldehyde, melamine formaldehyde and phenol formaldehyde resin, and two press temperatures of 175 and 185 ° C. OSB boards using poplar wood strands, 100 millimeters long were also produced as control samples. The results of strength measurements of the boards were statistically analyzed using factorial experiment and completely randomized block design. The grouping of the averages was based on Duncan Multiple Range Test. The results showed that the effect of the resin type on the flexural properties and internal bonding of the boards is statistically significant and boards produced using phenol formaldehyde resin exhibited the lowest modulus of rupture, modulus of elasticity and internal bonding strength. However, the adhesive type did not statistically influence the physical properties. The strand length also statistically influenced the board strength properties and boards made using poplar strands showed higher strength compared to corn stalks strands. The thickness swelling of the poplar OSB was almost twice the values of corn stalks OSB but the water absorption of these boards was lower than of corn stalks OSB. Press temperature adversely affected the modulus of rupture and elasticity, but higher press temperature improved the internal bonding strength. Higher press temperature increased the physical properties of the boards.

The purpose of this study was to use of Hemp stalks in particleboard production. Mixtures of Hemp stalk and Eucalyptus wood at the ratios of 0:100, 50:50, 100:0 were used. Also two resin content of 8 and 10% (based on oven dry particle) and 2 press times of 3 and 4 minutes were employed for the production of laboratory particleboard. Physical and mechanical properties including thickness swelling after 2 and 24 hours soaking in water, modulus of rapture, modulus of elasticity and internal bonding were measured data were statistically analyzed. It was observed that the increase in Hemp stalk particles in the mixture resulted in increasing of bending properties (bending strength and modulus of elasticity) and thickness swelling after 2 and 24 hours water soaking. Also the results showed that increase in Hemp stalk particles in the mixture resulted in reduction of internal bonding. As expected, physical and mechanical properties of particleboard improved with increasing resin content. Modulus of elasticity and thickness swelling after 24 hours water soaking were improved with increasing of press time. In general, comparing the produced board mechanical properties with standard of Iran requirements, the board produced using 100% and 50% Hemp stalk, 8% resin content and 3 minutes press time showed that optimal properties. Although the physical properties of the boards did not meet the standard values, the reason for this could not be due to the lack of use of paraffin.

In this study, the pruning branches of mulberry trees mixed with industrial wood chips were used in the manufacture of particleboard. Then the physical and mechanical properties of the boards were investigated. For this purpose the study variables included the amount of mixing mulberry branches with industrial wood chips in four levels 0/100, 10/90, 20/80 and 30/70 and the amount of urea formaldehyde resin at two levels 12 and 14% of the dry weight of the wood chips. The results showed that increasing the amount of particles obtained from mulberry tree branches up to 20 %, had no negative impact on the physical and mechanical properties of the boards. Increasing the amount of these particles up to 30 percent had a negative impact on the physical and mechanical properties of the boards, but with increasing the amount of urea formaldehyde resin up to 14 %, could be improved dimensional stability, bending strength, modulus of elasticity and internal bonding of the particleboards.

Current research was conducted to investigate the physical properties and internal bonding of High-Density Fiberboard (HDF) made from oxidized fibers and different amount of glue. In order to surface modification, fiber was treated with 40% nitric acid. After fibers gluing with urea-formaldehyde (7% and 9% based on the dry weight of fibers), the boards with a density of 0.9 g/cm3 were made by hot pressing at 175°C and 4 minutes. The results of spectroscopy were confirmed the reduction of hydroxyl functional groups and the increase of the carboxylic group due to oxidation. The results of short term immersion test in water showed that in boards containing oxide-modified fibers and 9% urea-formaldehyde glue were measured the minimum water absorption and thickness swelling with mean of 78.5 and 28.65%, respectively.Spring back of modified boards containing less glue was affected by the stresses release and debonding of the wood elements that resulted in internal bonding loss.

In this research, the manufacture of particleboard using lignocellulosic residues including wheat straw and tobacco stalks mixed with industrial wood chips were studied. The variable factors included the mixture of wheat straw and tobacco stalks with industrial wood chips in four levels 0/100, 20/80, 40/60 and 60/40 (In any combination, according to the desired levels, tobacco stalks and wheat straw were used equally) and the amount of urea formaldehyde resin was at two levels 12 and 14% of the dry weight of the wood chips. The results showed that by increasing the mixture of wheat straw and tobacco stalk up to 60 percent, the physical and mechanical properties of the boards decreased significantly. But increasing the amount of adhesive consumption up to 14 percent had a positive impact on the physical and mechanical properties of the boards and improved internal bonding, bending strength and modulus of elasticity and dimensional stability of the boards. It means that by increasing the use of this type of wastes up to 40 percent with an increase in the amount of UF adhesive up to 14% can be produced the boards with the mechanical properties at standard level.

In this research soy flour- tannin adhesives were used in particleboard preparation, successfully. Tow type of different tannins Mimosa (as condensed tannin) and Chestnut (as hydrolysable tannins) were used for soy resin modification. For this purpose, mimosa and chestnut tannin were added to soy adhesive with 5, 10 and 15 percent based on dry weight of soy flour. 9 percent Glyoxal was used based on dry weight of tannin for accelerate tannin reaction’s with soyflour components. Prepared soy-tannin adhesives were used in particle board manufacturing with 350×300×14 mm3 dimansion and 0.7 g/cm3 nominal density. Results of viscosity measurment showed that addition of each of tannins decreased visocosity of soy adhesive. In this study, result of thermo-mechanical analyze indicated that chestnut cloud improve adhesion behavior of soy adhesive better than mimosa. Also, Using of tannins in soy adhesive composition increase internal bonding and bending properties in manufactured particleboards.

Bio-epoxy tannin resin was made from tannin reaction with epichlorohydrin in an alkaline environment, Fourier transform infrared spectroscopy of epoxy groups of glycidyl reaction of the tannins confirmed, and the epoxy number was 7.2 epoxy resin final. Straw boards with Bio-epoxy tannin resin, using two variable temperature (180 and 200 °C) and variable times (7.5 and 10 minutes) were made. Physical and mechanical resistances such as water absorption and thickness swelling (after 2 and 24 hours soaking appears in water), internal bond, modulus and flexural modulus measured and the boards were compared with the standard EN312-4. The results showed that straw boards made with 200 °C and 10 minutes of press time, had the highest level of physical and mechanical properties. All boards produced in this research work, mechanical properties for public use, in accordance with the standards of Europe to have. That has functional properties comparable to petroleum-based synthetic adhesives are made of particleboard.

This investigation with aim of modified and improve the water resistance of Urea formaldehyde (UF) with help of adding Boric acid to this resin was performed. In this survey the purpose additive as a variable factor at four levels 1, 2, 3 and 4 was used compare to the dry weight of adhesive. After preparation the composites, Physical and mechanical properties were examined according to the ASTM, D1013-04. The results showed that the using of these additive caused increasing the water absorption and thickness swelling resistance of 2 and 24 hours after immersion in water, with these resin. Also using of these additive caused increasing the internal bonding in case of 24 hours after immersion in water, compared to the control sample but in case of dry caused decrease compared to the control sample. However was not lower than standard level. With increasing Boric acid levels to 2 percent, bending strength of the samples made compare to the control sample increased and after this level was decrease. Also with increasing the levels of specify to the 4 percent modulus of elasticity of boards made compare to the control sample were increased.

This study provides an investigation of particleboard manufacture using tannin-urea formaldehyde adhesive. Test board samples were made with regard to various replacement percentage of tannin–urea (levels of 0, 10, 20 and 30%) and press time (12 and 15 min) and their properties were determined. Achieved data were analyzed according to two sides factorial plan. The results showed that with replacement of 10% urea formaldehyde adhesive by tannin-formaldehyde at both 12 and 15 min pressing times, thickness swelling (after 2 and 24 hours immersion in water) was decreased while internal bonding increased. There were no significant effect on modulus of rupture and modulus of elasticity values. In general, the results of present research showed that replacing the UF resin at lower levels of tannin is suitable as adhesive to manufacture particleboard so that with replacement ratio of 90:10, the moisture properties of boards were very close to permissible those of the exterior wood uses.

Fiber external fibrillation is one of the refining effects in conventional refining which is accompanied with other effects such as internal fibrillation. Objective of the present study was to investigate the effect of fiber external fibrillation on paper properties. Softwood kraft pulp and poplar wood CMP pulp produced at Mazandaran Wood and Paper Industries was used. An ultra-fine friction grinder was used to generate the external fibrillation. Results showed that, increasing the fiber external fibrillation increased the density of paper sheets and lower refiner gaps decreased the light scattering coefficient. Increased fiber external fibrillation improved the tensile strength of the paper sheets by about 20% and internal bonding was increased from 33% to 46% compared with unrefined fibers.