جستجوی مقالات مرتبط با کلیدواژه « خواص فیزیکی » در نشریات گروه « صنایع چوب و کاغذ »

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.

This research was conducted with the aim of studying the effect of spraying with nano-polyurethane and freezing the treated samples on the physical and mechanical properties of brown liner paper. For this purpose, 128 g.m-2 paper was prepared and its characteristics were evaluated. To coat the surface of the paper, nano-polyurethane is first sprayed using a sprayer in an amount of about 15 grams per square meter for each surface. Then, the coated paper is placed in the environment and the oven (temperature of about 70 οC) to dry, so that the coating material stabilizes on its surface. Then the samples were placed inside the freezer for two and four months, before the tests of the control and coated samples, they were placed in standard environmental conditions (temperature of 20 οC and relative humidity of 65 %). The results showed that spraying increased thickness, decreased water absorption, and increased burst streangth, increased tear streangth. Also, there was no specific change in tensile strength and ring crush test. In sprayed and frozen samples, with the increase in thickness, water absorption and tensile strength decrease, burst streangth and tear streangth compared to non-frozen control samples, an increase was observed. Ring crush test against the was also not significant. The sprayed samples showed very few pores. The thickness and tear streangth in the machine direction of the one-time sprayed brown liner paper increased by 8.96% and 2.3%, respectively, compared to the control sample. water absorption, tensile strength and tear streangth, burst streangth and ring crush test against the ring in the machine direction of one-time sprayed brown liner paper compared to the control sample showed decreased as 19.53, 3.83, 2.4 and 3.14, respectively.

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.

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.

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.

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 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.

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.

The purpose of this study was to improve properties of the coated papers by calendering. Two types of printing and writing paper (75 and 125gsm) and five coating suspensions (the first suspension with 22.9% binders and 50% solids content, the second with 24.73% binders and 50% solids, the third one with 22.9% binders and 30% solids, fourth suspension with a 24.73% binders and 30% solids and the fifth suspension with 42.3% binders and 50% solids content) were used. The coatings were composed of 80% kaolin clay, 20% ground calcium carbonate, dispersant and different ratios of polyvinyl acetate and lactic acid. The base and coated papers were dried after coating. The calendering treatment was carried out at a temperature of 55° C and 60 kg/cm linear pressure. Air resistance, thickness, water absorption, tearing resistance and bursting strength of papers were determined. The calendering operation was effective in reducing the thickness and increasing the air resistance. Water absorption was decreased only in 75gsm samples. In the effect of calendering the mechanical properties were improved slightly, but in most cases, had an adverse effect on the mechanical indexes.

The purpose of this study was to evaluate the biodegradability of composites made from bamboo flour and poly lactic acid using physical properties and biodurability examinations. On the other hand, the effect of the amount and size of the bamboo flour particles on the physical properties and durability of the biocomposites was another objective of the research. the bamboo flour and polymer were mixed up in a counter-rotating twin screw extruder. the biocomposites boards were produced by compression molding method. The samples were cut and evaluated according to the suggested specifications in the ASTM and EN-113 standards. The results showed that the thickness swelling and water absorption of the composites were increased significantly by increasing the amount and size of bamboo flour particles. Also, biodurability of the biocomposites samples against the studied three fungi species showed that Gloeophyllum trabeum sharply caused high mass losses in all samples by increasing the amount of bamboo flour, while pure polymer (PLA) had a very high durability against the fungi.

The purpose of this study was to measure the amount of quality decrease the Hornbeam (Carpinus betulus) wood after three period four months (12 months) of storage in the forest and compare it with the beginning of the period and identify the destroyer fungi that appeared. This research was carried out in Shastkolah in Gorgan. 15 Billets with 30 cm diameter class and length of 220 cm were cut from a Hornbeam tree and all were healthy and stored inside the forest under the same conditions and in contact with soil. The billets were cut at 50 cm intervals at each stage for physical and mechanical experiments were measured based on conventional methods and related standards. the white decay fungi Sterium hirsutum (Willd.),Trametes gibbosa Fr.,Trichaptum biformis Fr. identified on the billets. According to the results, with increasing storage time in the forest, all physical and mechanical properties, except water absorption, decreased. The maximum and minimum changes in physical properties were related to the percentage of water absorption and basic density respectively, also the maximum and minimum changes in mechanical properties related to impact resistance and modulus of elasticity respectively

The Use of agricultural plants wastes as an alternative forest resources in the cellulose industry can be recommended due to the severe shortage of wood raw material and restriction of forest harvesting. The aim of current research was to investigate the effect of thermal modification on applied properties of composite made from sunflower stem flour-polypropylene. Thermal modification of sunflower stems was done at temperatures of 160, 180 and 200°C for 30 minutes and mixed with polypropylene in ratio of 30wt%. Test samples were prepared with maleic anhydride-grafted polypropylene as coupling agent by injection molding method. FTIR spectroscopy of sunflower stem flour confirmed the chemically changes due to thermal modification. More integration and uniform distribution, and less cavities were observed in the scanning electron micrographs of failure surface. The removal of hemicellulose of sunflower stem flour improved the thermal stability of composite, which thermal gravimetric analyzer (TGA) confirmed it with increasing in modification temperature up to 180°C. Modification at 200°C decreased thermal stability compared to other temperatures. Thermal modification leads to significant decrease in water absorption and improvement in bending and tensile properties due to hemicellulose degradation, increasing the crystallinity, loss of polarity, increased compatibility between the two phases of composite and uniform distribution of fillers in polymeric matrix. Notched impact strength of modified composites decreased due to better adhesion between lignocellulosic filler and polymer that facilitate the crack development along the interface.

The potential of rose flower stalks for the production of particleboard was investigated. Three resin dosage gradients of 0, 2 and 4% (10% core: 10% surface; 9%core:11% surface and 8% core:12% surface) and three press times (3, 4 and 5 minutes) were selected as the variables and boards were produced. Then the mechanical and physical properties of the boards were measured and statistically analyzed. The results of modulus of rupture (MOR), modulus of elasticity (MOE) and internal bonding (IB) measurements showed that as the resin dosage gradient increases, these properties improved and boards produced using either 2 or 4% resin dosage gradients generated the highest values. The effect of resin dosage gradient on these properties was statistically significant. As the resin dosage gradient increases, both thickness swelling after 2 and 24 hours immersion in water was improved. The effect of press time on thickness swelling after 2 and 24 hours immersion in water was also statistically significant and these properties were improved when 5 minutes press time was used The results indicate that if 2 or 4% resin dosage gradients and either 4 or 5 minutes press time is applied for the manufacturing of particleboards using rose flower stalks residues, the specification of the boards will meet the EN specification.

In this study, the effect of different catalysts on chemical modification of poplar wood and physical properties of the resulting product was evaluated. 12.5% HCl and water soluble salts containing ZnCl2, CaCl2, AlCl3, MgCl2 (based on the weight of glutaraldehyde) and 1% Al2O3, SiO2 and ZnO nano particles (based on the weight of glutaraldehyde) were used. After heating in oven for 48 hour, modification with glutaraldehyde and MgCl2, ZnO nano particles, SiO2, Al2O3, ZnCl2, AlCl3, CaCl2 and HCl as catalysts were resulted to 14.5, 12.57, 10.62, 8.69, 8.51, 7.19, 5.97 and 5.41 % weight gain respectively. After 24h soaking in water, the physical properties of modified specimens, such as water absorption, volume swelling and ASE were measured. The highest and lowest bulking were calculated for Mgcl2 and Hcl catalysts with 6.98 and 2.37% respectively. The modification in presence of Mgcl2 catalyst was shown highest increase of density with average of 0.55 g/cm3. The highest and lowest water absorption was measured 79.61 and 45.32% in the modification with HCl and MgCl catalysts. Hcl with acidic quality, can break ether bonds in hemiacetal and even acetal structure. Modification with MgCl2 was shown best result in comparison with other catalysts. It is likely that the formation a complex of magnesium with oxygen, could resulted to activate carbonyl groups in glutaraldehyde and created the crosslink.

In this study, the effect of using Layer-by-Layer (LbL) treated pulp as mixed with refined OCC recycled pulp was investigated on paper physical properties. The LbL treatments were conducted to build 7 consecutive cationic and anionic starch layers. Afterwards, at three levels of 10, 20 and 30 percent, LbL-treated pulp was added to the 10, 15 and 20 minutes refined pulp. From mixed pulp, handsheets with basis weight of 60 g/m2 were prepared and its physical properties including: thickness, density, roughness and formation was examined. The results of LbL treatment using AFM micrographs indicated that the surface of fibers was covered with starch polymer particles by means of Layer-by-Layer treatment. Also, SEM micrographs confirm starch impregnated fibers surface and formation of rough surfaces. Analysis mutual effect of independent variables revealed that addition of LbL-treated pulp to the refined recycled pulp had only significant effect on paper thickness and surface roughness, while variation of refining time had significant influence on all physical properties. In current research, considering the results of ANOVA test and the mutual effect of the content of LbL-treated pulp and different refining time levels on the paper physical properties using response surface methodology, adding of 10 % of LbL-treated pulp to the OCC pulp and applying the refining time of about 18.66 minutes was selected as optimum condition.

The objectives of this research determine for optimum condition modification with effect of 3-(trimethoxysilyl) propyl methacrylate on physical properties of Poplar wood-polymer were performed. Test samples from Poplar species were divided to five levels: control, Acidified Ethanol/Silan/110 ˚C, Acidified Ethanol/Silan/150 ˚C, Ethanol / Silan / 150°C and Silan/150°C in two levels with and without Benzoyl peroxide. Samples were impregnated with silan compound according to vacuum-pressure method in experimental cylinder. Weight percent gain of Silan/Et/BP/150 ˚C level by 24/40% had the maximum value were determined. Bulking efficiency and OH groups substituted in Silan/AEt/150 level with 6.81 % and 1.10 mol/gr, respectively compared with the other levels.
Modification were resulted to improve water absorption and dimensional stability that maximum dimensional stability in contain initiator level were determined. In immersion-dry period test, the highest and lowest bulking efficiency in Silan/AEt/150 and Silan/Et/150 were reported. Maximum of weight loss in immersion-dry test was determined in Silan/AEt/110 with the 3.6% value.
Key words: physical properties, 3-(trimethoxysilyl) propyl methacrylate, Asidified Ethanol, bulking efficiency.

Current research was conducted to investigate the effect of thermal modification on practical properties of horn beam bark flour-polypropylene composites. Wood plastic composites were divided in two levels of control and thermal modification, both levels included of 4 groups in bark fillers; 10, 20, 30 and 40%. Test samples prepared with maleic anhydride-grafted polypropylene as coupling agent by injection molding method. According to the results, bark flour increased water absorption, tensile and bending modulus. High proportion of bark fillers declined mechanical strength. Thermal modification significantly improved physical and mechanical properties of composite. Using lignocellulosic material flour bark hornbeam, tensile modulus and flexural modulus of composite material background had the highest improvement. In comparison between mechanical properties, impact resistance by adding flour bark had the greatest decrease. Thermal modification by increasing the crystallity, hemicellulose degradation, loss of polarity, increased compatibility between the two phases and uniform distribution of bark fillers in polymers, increased mechanical resistance.