جستجوی مقالات مرتبط با کلیدواژه « wood » در نشریات گروه « جنگلداری »

The aim of this study was to evaluate the effect of white rot fungus (Trametes versicolor (L.) Lloyd) on physical and mechanical properties of treated and untreated poplar wood (Populus deltoides Marshall and P. nigra L.). Heat treatment was used as wood modification. Heat-treated and untreated poplar wood specimens were evaluated after exposing to the white rot fungus for 16 weeks. The evaluated properties was included: laccase activity, mass loss, density changes, impact strength and compression strength parallel to grain due to thermal modification and also fungus efficiency. Evaluation of lacase activity showed more efficiency of this enzyme in controls in compared to modified specimens in which also caused more mass loss. In both two poplar wood species, thermal modification reduced the density and the impact strength of the specimens, but improved the compression strength parallel to grain. Evaluation of physical and mechanical properties of the specimens exposed to white rot fungus also showed that thermal modification limits efficiency of this fungus on both poplar wood species. As a result, the reductions in the studied physical and mechanical properties, including mass loss, density, compression strength parallel to grain, and impact strength, were significantly more pronounced in the control group than the modified specimens.

Wood is a valuable material that is produced and treated in the forest workshop using natural resources. The history of these workshops reveals the significance of wood in human life across many regions of the world. As collecting wooden specimens became increasingly popular over time, museums and herbariums emerged to house valuable plant and animal collections. One unique type of collection is the xylarium, or wooden herbarium, where wood samples are stored. The term "xylothek" was originally used when these collections were made available to the public. Xylaria distinguish between collections created for scientific and educational purposes and informal ones made by craftsmen and artisans. The creation of these collections was primarily intended to facilitate collaboration and exchange among the world's greatest xylaria. They also allow for systematic studies by wood anatomists, researchers, and scientists in other fields. Additionally, they serve exhibition, educational, cultural, historical, and commercial purposes. In recent years, modern technologies such as imaging, image analysis, measurement, and artificial intelligence have made it possible for artisans to identify wood with greater precision. These collections have immense value because they increase awareness of biological reserves and attract the attention of experts who record and collect information about them. Wood blocks may seem silent, but they have tremendous potential to enhance our understanding of the natural world and contribute to its preservation.

Rural communities in developing countries are facing challenges for their livelihood due to various reasons such as resources limitations, low income and job opportunities. In forested areas, wood and non-wood forest products have created an opportunity for self-consumption and have become a source of income for local residents. In this regard, the present study seeks to identify the type and rate of forest product utilization and its impact on livelihoods of local communities in the Jaji Aryub forests of Paktia province, Afghanistan.

This study was an applied study that was conducted as a survey in Jaji Aryub forests of Paktia province in Afghanistan. The statistical population of the study consisted of 1404 household heads in 14 villages, of which 303 were selected based on Krejcie Morgan table. The main research instrument was a researcher-made questionnaire consisting of 20 items related to the type of forest products use in five sections: 4 items fuel consumptions, 3 items construction consumptions, 7 items food and nutrition uses, 2 medication uses, 4 items outdoor recreational services. Livelihood level of the local communities were studied in three dimensions of employment and income with 12 items, nutrition and health with 5 items, and support and housing with 6 items. Expert opinion was used to determine the content validity of the questionnaire and calculated Cronbach's alpha coefficient was used to estimate its reliability. After data collection, analysis was performed using SPSS 21 software in two parts: descriptive and inferential statistics.

According to the respondents' viewpoints, in average, fuel consumption with 3.94 and outdoor recreation with 2.57 (from 5 point), had the highest and the lowest using rates by local communities, respectively. Livelihood of rural families was correlated to usage of wood and non-wood forest products with medium rate (approximately 3 from 5) in three dimensions of nutrition and health, support and housing, and employment and income. The results indicated that, there is a significant positive correlation between the using rate of forest products by local communities and their total livelihood (99% confidence level). The results also showed that there was a positive significant relationship (99% confidence level) between respondents' use of forest products and their age and number of household members with correlation coefficients of 0.163 and 0.148, respectively. While a negative significant correlation with their education level were distinguished.

livelihoods of local communities in the Jaji Aryub forests of Paktia province, Afghanistan are, highly, depended to the forest resources due to various reasons such as environmental limitations, individual characteristics, lack of welfare, and limited income and job opportunities. Providing new energies (solar radiation, wind and oil), new job opportunities, creating local and regional markets and supplying processed products, as well as conducting training workshops based on participatory and social forestry were recommended.

In this study, the possibility of using superchrome and Fantachrome coatings on beech and poplar surface was investigated. Initially, samples were cut into 2×10×10 cm dimensions and after coating with superchrome and fantachrome paints, pull-off and cross-cut adhesion, contact angle and gloss tests were performed on their surface. The properties of coated surface was investigated by light microscopy. According to the results, the contact angle of the coated samples with superchrome and fantachrome significantly increased compared with the control sample in both beech and poplar species. The highest and the lowest amounts of pull-off adhesion strength of superchrome and fantachrome coatings were in fantachrome-coated beech and superchrome-coated poplar, respectively. Also, the results of cross cut adhesion test confirmed the results of pull-off test. After coating, the gloss content of the specimens significantly increased and the highest gloss was related to fantachrome coatings on beech and poplar samples, 141.8 and 141.7 gloss units (GU), respectively. In addition, the results of microscopic examination showed that the primary primer of the coating penetrated the wood texture by 4 microns but the surface chrome coating was 11 microns thick on the wood surface.

Considering the high cost of the methodical construction of buildings and the use of engineered and safe materials; the structure such as gypsum board has been interested of experts in wood and construction industry. The reason is important features such as low production costs and high earthquake resistance. Moreover, it’s important to determine effective criteria for decision-making for the establishment of industrial units aimed of optimal use of raw materials, the production process and approaches to reduce costs and waste. To achieve this, paired comparative analysis method was selected and after initial studies, field surveys and interviews with experts, 5 main criteria and 32 important sub-criteria were identified. After that, the paired comparisons questionnaires were prepared and filled out by academics and a number of managers and experts in wood and construction industry. The results revealed that among the first level criteria, material and product, economic and financial criteria have the highest priorities, respectively. Besides, sub-criteria of ensuring the sustainable supply of gypsum resources, raw materials costs, background of the mineral composites, background of the construction industry, distance from the gypsum resources, content of the gypsum resources finally the amount of sale had the highest priorities, respectively.

Wood is a natural material used in the construction of various wooden structures. Due to the presence of wooden structures in the outdoor, wooden structures are weathering and surface degradation. Regarding the use of wood as outdoor furniture, flooring, parquet and wooden houses, some properties such as hardness, scratch resistance and abrasion are important. In this study, the effect of accelerated weathering on the abrasion resistance of Populus nigra, Fagus orientalis and Quercus castaneifolia was studied.

For this purpose, wood samples were cut to standard dimensions of 2×10×15 cm (L × R × T) and the surfaces of wood samples coated with linseed oil (100 mlm3) and for 2 weeks were kept in accelerated weathering. Then, by Taber test and Confocal laser microscope, the abrasion resistance and topography of the wood surfaces before and after weathering were investigated.

The results of this study showed that, due to weathering, the wear resistance of all wooden species decreased and the more resistance among them was related to oak with the weight loss of 1.7 grams. Also, the results showed that the amount of abrasion index reduced by 28, 38 and 18 percent for poplar, beech and oak, respectively. The lowest and highest abrasion resistance after weathering was related to the poplar and oak and the results of the laser microscopy showed that, in the poplar, beech and oak the abrasion depth was 201, 183, and 136 (μ), respectively. The results also showed that, there was a significant difference between coated and uncoated samples.

The increase in oak wear resistance to other species can be due to higher specific gravity. In addition, the use of linseed oil coating reduces water absorption and, on the other hand, reduces friction and makes the surface of the wood lubricate. Also, the increase in weight loss after weathering is due to the higher absorption of uncoated samples than the coated samples, which causes faster and easier destruction of the wood structure. Based on the results of the laser microscope, the coating with linseed oil has been able to reduce the wear depth and reduce wear resistance. According to the results of this study, linseed oil can be used to increase the resistance of wood structures to abrasion.Based on the results of the laser microscope, the coating with linseed oil has been able to reduce the wear depth and reduce wear resistance. According to the results of this study, linseed oil can be used to increase the resistance of wood structures to abrasion.

In this study, physical properties and leach resistance of eastern cottonwood-polymers that treated with copper oxide nanoparticles were studied. According to ASTM D4442 Standard, Wood samples converted to 20×20×20 mm dimensions, then were impregnated with polymers and nano copper oxide by full cell method. In this research variable factors were polymers (furfuryl alcohol and styrene monomer), concentration of polymers (40 and 80 percent) and nano copper oxide (in of concentrations 0, 0.4 and 0.8 percent). After preparing Samples, they were immersed in 100 ml of DI water and their water absorption, volumetric swelling and leach resistance were calculated. Obtained results showed that there are significant differences between treated and untreated samples, where treated samples had less volume of water absorption and volumetric swelling. Also samples treated with furfuryl alcohol and nano copper oxide showed better performance on physical properties in compare to samples treated with styrene monomer and nano copper oxide. In the case of leaching, treated samples with polymers had the least amount of copper leaching so that leaching values were less than 1 percent in most of them. After preparing Samples, they were immersed in 100 ml of DI water and their water absorption, volumetric swelling and leach resistance were calculated. Obtained results showed that there are significant differences between treated and untreated samples, where treated samples had less volume of water absorption and volumetric swelling. Also samples treated with furfuryl alcohol and nano copper oxide showed better performance on physical properties in compare to samples treated with styrene monomer and nano copper oxide. In the case of leaching, treated samples with polymers had the least amount of copper leaching so that leaching values were less than 1 percent in most of them. significant differences between treated and untreated samples, where treated samples had less volume of water absorption and volumetric swelling. Also samples treated with furfuryl alcohol and nano copper oxide showed better performance on physical properties in compare to samples treated with styrene monomer and nano copper oxide. In the case of leaching, treated samples with polymers had the least amount of copper leaching so that leaching values were less than 1 percent in most of them. After preparing Samples, they were immersed in 100 ml of DI water and their water absorption, volumetric swelling and leach resistance were calculated. Obtained results showed that there are significant differences between treated and untreated samples, where treated samples had less volume of water absorption and volumetric swelling.

In this research, the hydroxyl (OH) accessibility in the beech, spruce and pine wood was measured by impregnation of the wood specimens with heavy­ water (D2O) (deuterium exchange). After impregnation of wood specimens with heavy water and drying in a vacuum oven, the relative hydroxyl accessibility (% accessible hydroxyl groups) was determined with ATR-FTIR spectrometry by calculation of the integrated peaks for the OH and OD stretching vibrations at wavenumbers of 3500 and 2500 cm-1, respectively. The absolute accessibility (mmol hydroxyls/g wood) was determined using an advanced dynamic vapour sorption equipment, (DVS-ET1) by measuring the increased dry mass of the sample due to deuteration after conditioning with heavy water at 95% RH. The results showed that the relative accessibility was not affected by the wood species and its extractive content and more than half of the hydroxyl groups could be accessible. The absolute accessibility in spruce was higher than that in beech. For spruce wood, the earlywood had less accessible hydroxyl groups than the latewood. The poor linear correlation between the hydroxyl accessibility and equilibrium moisture content (EMC) confirmed that the moisture absorption by wood was not controlled exclusively by the hydroxyl accessibility.

With the aim of identifying failure mechanism in oriented strand boards, failure behavior of wood strands under tensile load was investigated using acoustic emission technique. Resinated and unresinated strands were arranged at top, middle and bottom section of the board before pressing. Tensile and acoustic emission tests were performed simultaneously on treated and control samples. Using tensile test data, module of elasticity and ultimate tensile strength of specimens were determined. Acoustic emission data were used for calculating cumulative events, cumulative energy and amplitude of the signals. The results showed that increasing in amount of load and time resulted in increasing of the amount of acoustic emission cumulative energy, event and the maximum signals amplitude. The considerable increase of cumulative energy and events were achieved at the time of failure. The treatment conditions influenced the acoustic emission results and pressed specimens released higher acoustic energy and had higher cumulative acoustic emission events, in comparison to the other specimens. Generally, the magnitude of acoustic emission indices was proportional to mechanical properties such as elastic modulus and tensile strength indicating that failure in strands can be identified by acoustic emission.

Equilibrium moisture content (EMC) of wood is one of the major indicators in wood industries. Determine of EMC in different locations of services, can prevent from wood waste due to meteorological parameters. This study was performed to estimate the relationship between EMC and the geo-statistical parameters (latitude, longitude and altitude). The results showed that the coastal and cool climate and locations have EMC higher than dry and central locations of Iran. The winter months, the early months of spring and fall months leading up to winter season have more EMC. The analysis showed that the spatial variations of the two variables latitude - height equation provide better results than the uni-variable equations. So, multivariable equations showed better results in compare with uni and two variable equations. The good results obtained in the multivariable equations in the warmer months. The best way to assess the EMC by spatial variables is regional scale study of EMC, inclusion of climatic conditions, remoteness and proximity to water sources and finally specific climate modeling for any region.

Fracture of mixed mode I/II in beech wood and its wood polymers has been investigated experimentally in this study. Hence, two crack systems of TL and RL were selected in which the crack planes extend along the wood fibers. This investigation has demonstrated that onset of mixed mode cracking can be predicted with a very simple fracture criterion in these crack systems. Results indicated that fracture critical loading is affected by furfurylation and also load-displacement curves of specimens were changed. Variations in fracture toughness values of mixed mode I/II can be occurred following variations of fracture critical forces. In the both crack systems, KIC/KIIC distribution trend is changed by furfurylation that indicates changing of material nature by furfurylation. Results of scanning electron microscopy (SEM) analyses indicated that micro cracks occurrence in wood polymer structure may be one of the factors caused to change in fracture toughness; these changes occur simultaneously with material nature modification followed by increasing of shear strength parallel to the grain due to polymerization.

Wood-plastic Composite is one of the newest products in the world and has experienced huge growth in recent years. There is great potential for use of these products in various ways, so it is necessary to identify and evaluate the effective criteria on acceptance of this product among Iranian consumers. The methodology of research is descriptive analysis and after reviewing the literature and interviewing with industrial and academical experts, 10 effective criteria were identified and a questionnaire has designed in accordance with the principles of the LIKERT scale in order to determine the importance and priority of these indexes. The results show that the factors affecting the wood-plastic composites market doesn’t have equal importance in opinion of Iranian consumers. Among the properties of this product, moisture resistance usage range and customer satisfaction have more importance respectively. These criteria should be considered by manufacturers and suppliers in Iran. The most common reason of the acceptance of wood-plastic composites are moisture resistance properties and it can be replaced by other wood products because of good durability and Plasticity, however its high price compared with compact wood panels have to be considered.

Tobacco is planted extensively in Golestan province and high volume of its stem wastes remained without using and it is burned. As a useful purpose of these wastes and to reduce the environmental problems، in this the mechanical properties of polypropylene composites reinforced with tobacco stalk flour were studied. For this purpose، the tobacco stalk flour as the reinforcement، in three levels of 30، 40 and 50%، maleic anhydride grafted polypropylene as a coupling agent in two levels of 4 and 6% as variable factors were used. The results showed that with increasing the amount of tobacco stalk flour، tensile stress decreased significantly but tensile modulus increased. Also increasing the amount of coupling agent improved tensile strength. Bending strength and bending modulus increased with increasing the amount of tobacco stalk flour and coupling agent. In the case of impact strength، no significant effects were observed between the different levels of the treatments. Therefore it is recommended to use50 % tobacco stalk flour as a natural and biodegradable material with 6% coupling agent to make wood-plastic composite with desired mechanical properties.

In this study، the efficiency of nano-zinc oxide and zinc borate with four mixing ratios of 0، 1، 2، 4 wt% on the biodegradation resistance of wood plastic composite (containing 50 and 70 wt% wood flour) were investigated. Briefly، the composite samples were manufactured using internal mixer and compression molding، followed by exposing to the white rot fungus، Trametes versicolor. The obtained results indicated that no significant weight loss happened in composites containing zinc borate. But، the addition of nano zinc oxide with loading fraction of 2 and 4% to the structure of composites containing 50 and 70 percent wood، significantly reduced weight loss. In the composites containing 50% wood، the results of flexural strength loss matched with weight loss at the end of the decay experiment، while the composites containing 70% wood، the flexural strength loss was not in good agreement with the results of the weight loss.

In this study, The effect of alternative humidity stages on Physical and mechanical properties of Rice stem flour (RSF)-Polypropylene Composites was considered. Panels composites were built in 1g/cm3 nominal density and 25×15×1cm dimension that including, treatment of PP and RSF with 45, 60 and 75% weight ratios. Physical and mechanical properties of composites were measured and data were compared with randomized design. The Results showed that increasing of filler ratio, and passing of humidity stages result in decrease of Physical and Mechanical properties of composites. Adding 2 percent MAPP result in partial improve in Mechanical properties and decrease in water absorption and thickness swelling of composites.

In this study, the effects of zinc borate with or without UV absorbent and antioxidant on the durability of wood-high density polyethylene (HDPE) composites were investigated during artificial weathering. colorimetry and tensile strength were determined after 0, 500, 1000 and 1500 hrs. Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) analyses were also carried out before and after 1500 hrs accelerated weathering. The results indicated that zinc borate had no effects on the weathering resistance of wood-HDPE composite. The use of antioxidant increased surface degradation of the composite evidenced by FTIR and DSC analysis. The color and tensile strength stability and FTIR analysis indicated that the composite was protected by UV absorbent.

With regard to the importance of the conduction of limit resources to the superior industries، study on the country’s priorities in the industrial areas and products is essential. Considering the fact that Qom province has special conditions، this provincecan be consideredas a wood centerin the wood industry in which prioritizing the wood and paper industries is essential. To reach this goal two stepsare needed to be taken، the first step is to design a hierarchy based on five major groups of criteria which are financial & economical، infrastructure، material & product، technical & man force، and social & cultural. The weight of the indicators was established by Analytical Hierarchy Process. In the second step، based on the criteria weighing values، alternatives have been ranked through TOPSIS. The results showed that financial and economical criterion as a major group has the highest priority with. 28 weighing value and investment attraction as a sub criterion has a weighing value of. 11. Besides، the results of the alternatives ranking showed that the other types of wood furniture alternative gain the maximum priority and the printing، writing، and newspaper papers gains the minimum priority.

Skidding by ground-base Machines in mountainous forests of northern Iran on selective cutting leads to physical damages of residual stand, lowering of stem quality and tree value in border skid trail. In present research, two conventional methods (picket-wood and machine tire) as well as rubberized - stem were evaluated for preventing damage to surrounding stand and compared with the control. In this regard the study was carried out in parcel 212 of Shorab district, in Golband Forest. Following the end of skidding operation, affected area for any single tree was measured. and data were subjected to analysis of variance. Differences among means were determined by Duncan test. Results showed significant statistical differences between scar severities due to skidding operation in different stem protection methods. Based on the obtained results, picket-wood, machine tire and the control trees were in class one and Rubberize-stem was in class two. Furthermore, there were significant difference between scars in two angle class (100 -140 and 140-180 grade) and the scar height classes. Use of rubberized-stem in skidding operation, will result in fewer trees affected and less scar dimensions..

Wood resistance of forest species to fire has effective role in preventing forest fire development and expansion. Thus, the aim of this research was to study the tree species wood resistance to fire and to measure the time needed for complete wood burning, considering the wood’s moisture and bark. The trial was conducted under the Completely Randomized Experimental Design with six replicates, 10 forest species (Carpinus betulus, Alnus glutinosa, Parrotia persica, Fagus orientalis, Pterocarya fraxinifolia, Acer cappadocicum, Acer velutinum, Cupresus sempervirence var horizontalis, Quercus castaneifolia and Zelkova carpinifolia), two levels of wood moisture (dry and wet or natural moisture) and two barked and bark free treatments. The woods were burnt at 400°C and the time needed for complete burning was measured by a chronometer. The results showed that the resistance of wet woods to complete burning was 2.3 (Quercus castaenifolia) to 2.9 (Parrotia persica) times more than the dry woods. Carpinus betulus and Parrotia persica had the greatest and the lowest resistance to complete burning, respectively. Moreover, the resistance of Fagus orientalis, Acer cappadocicum, Acer velutinum and Zelkova carpinifolia to complete burning increased, respectively. Bark increased the resistance of some species to complete burning, for instance the time difference for complete burning of wet and dry woods of Fagus orientalis, Cupressus sempervirens var. horizontalis, Acer cappadocicum, Acer velutinum and Zelkova carpinifolia was 46, 82, 110, 116 and 169 seconds, respectively. Although Alnus glutinosa and Pterocarya fraxinifolia had high capacity to establish in sites with poor drainage, but they had a very low resistance to fire. Therefore, it is recommended to plant Fagus orientalis, Acer cappadocicum, Acer velutinum, Parrotia persica and Zelkova carpinifolia as an alive firebreak in areas with high fire risks (naturally and human related reasons), for instance near forest roads and tourism centers, for their capacity to prevent fire development and expansion

Currently a part of our wood requirement is supplied through imports from Russia despite the potential risk of quarantine pests and diseases entering the country. Quarantine pests and diseases may be transformed with wood from home country to another and in some cases acquired heavy tool to the forests of destined countries. Considering the importance of the quarantine risks posed by wood imported from Russia a research project was conducted during 2007 to 2009. In the course of implementing the project, regular seasonal inspections were conducted of the imported woods as well as the woods used for load leveling in four points of entry including Astara and Anzali in Gilan, Noshahr and Amirabad in Mazandaran. In case of pests occurrences, conventional direct sampling methods including aspirator, forceps or hair brushes were applied. Following collection and labeling, samples were preserved in glass vials containing 70% alcohol. The primary points of concern were ongoing malpractice and negligence in physical inspection, clearance and treatment procedures in the customs. Better knowledge of the above mentioned subjects would ultimately modify and improve the whole system.