The purpose of the present research is enhancing the thyme essential oil efficacy by microencapsulation technique with emphasis on controlled released mechanism. First, essential oil was extracted by hydro-distillation in a Clevenger-type apparatus for 4 h. Then, core-shell microcapsules were prepared using solvent evaporation method with oil in water emulsion system. To measure the efficacy of encapsulated thyme oil, UV-visible spectrometer was used and was found to be 67 percent. The size and shape of oil droplets in emulsion were observed with optical microscope and the morphology of the polymer capsules was observed with scanning electron microscope. Release kinetics in both free and encapsulated forms showed that all components of free oil evaporated into atmosphere, while just 6 percent of capsules evaporated in the same condition. So, microencapsulation method increased the efficacy of the essential oil with controlled release mechanism. Filter paper disk test was performed to investigate the fungicide effects of thyme oil in both free and capsulated forms before and after leaching test. Results revealed that there are no significant differences between control samples and those treated by free oil especially after leaching test. In contrast, the samples treated by microencapsulated thyme oil showed much more resistance against Aspergillusniger mold indicating that the controlled release mechanism can prevent mold growth on filter paper disk and therefore improved the oil efficacy.
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.
In this study, Effect of weathering on Surface properties of HDPE-based wood plastic composites was investigated. The variable factors were titanium dioxide nanoparticles content (0, 1, 2 and 3%), raw material type (heat treated wood and untreated wood) and photo stabilizer (0 and 1%). Lightness index (L*) and color changes (∆E) were investigated after 0, 500, 1000 and 1500 hours weathering. Chemical changes and surface deterioration that occurred due to weathering were also analyzed using Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM) before and after 1500 hours weathering. Transform Infrared Spectroscopy (FTIR) of WPCs showed that carbonyl index increased and wood index decreased after weathering. Scanning electron microscopy (SEM) also showed that weathered samples experienced surface deterioration. Wood plastic composites containing titanium dioxide nanoparticles, thermowood (heat treated wood) and tinuvin 328 (photo stabilizer) showed less surface cracks after weathering compared to control sample. Carbonyl index and wood index changes of samples containing titanium dioxide nanoparticles, thermowood and tinuvin 328 decreased after weathering compared to control sample. The results also showed that lightness index and color change of samples increased after weathering. The color stability of WPCs was improved by using of wood plastic composites containing titanium dioxide nanoparticles, thermowood and tinuvin 328.
Wood farming is one of the strategies of agricultural development programs to reform unsustainable exploitation of natural resources. Poplar is one of the known species for wood farming in the country. This species is fast-growing and has numerous Colognes has the ability to adapt to different climatic conditions. Fast growth, good economic returns and traditional agricultural knowledge, favorable habitat to agriculture are advantages of poplar for agricultural development. However, the result of previous studies indicates existing barriers to the development of plantation and its development need strategic planning. What seem essential today are strategies to overcome these obstacles. Accordingly, this present study with a holistic view trying to identify the strengths, weaknesses, opportunities and threats of poplar farming. And the most appropriate strategies for the development of poplar farming in Urmia have offered. This research was a Field study and conducted using questionnaires. In this study, strategies were defined using SWOT analysis and the strategies were prioritized using analysis network process. The results showed the history of poplar farming in this region is the most important benefit to development and the many uses for poplar wood is the next priority. Increasingly replacement of poplar farming with alternative cultures is one of the main weaknesses of poplar farming development in this region. After that long return of profitability in poplar farming is the second priority. The most important opportunities for the development were the development of credit specialists to support of poplar farming and the most important threat was lack of annual financing of farmers. Also the results of strategic prioritization showed, Modern irrigation methods to reduce water consumption and planning to teach correct principles of technical planting, farming and harvesting are considered as the most important strategies.
In this study the effect of nanoparticles of Cerium dioxide (CeO2) and The combined effects bundled with nano-silica in Order to improve the physical properties of polyurethane clear coatings on Thermally modified wood of spruce (Picea abies) substrate were examined. For this purpose, different formulations of polyurethane coatings containing different amounts of the nanoparticles were applied on the heat treated wood surface after preparation. The presence of nanoparticles in polyurethane nanocomposite coating structure was confirmed by EDS analyses. To examine the effects of nanoparticles, adhesion, surface roughness and hardness of polyurethane coatings were assessed. The results showed that the use of cerium dioxide caused to improve the performance of polyurethane coatings on heat treated wood by reducing roughness and increasing adhesion strength of coating layer. In addition, the hardness of polyurethane coating layer enhanceded in the presence of cerium dioxide. Silica nanoparticle in the polymer matrix linked to cerium dioxide gave rise to enhance the adhesion strength and roughness of nanocomposite coatings.
In this study, physical and mechanical properties of single layer particleboard made from bamboo powder (with and without alkali treatment) and wood particles were investigated. Bamboo powder (30 mesh particles) was treated with 5% hydroxide sodium for 120 minutes. Industrial wood chips from Sanate Choube Shomal Company were used.The variable in this research were the ratio of bamboo powder (with and without alkali treatment) to wood chips (at four levels; 0:100, 10:90, 20:80, 30:70). Urea formaldehyde resin used at 10 percent level of dry weight of raw material as well as ammonium chloride was used as a catalyst at 2 percent level of the dry weight of adhesive. Physical and mechanical properties of panels measured according to EN Standard. Mechanical properties of the particleboards made from treated bamboo was superior to the relevant untreated bamboo. Water absorption and thickness swelling after 2 and 24 hours immersion in water decreased with alkali treatment. Mercerization, or treating cellulose fibers in alkaline solution, because of fibrillation, the removal of lignin and hemicellulose enhances the mechanical properties and dimension stability of the particleboard by promoting resin-fiber mechanical interlocking at the interface. Results showed, there was usability of the treated bamboo up to 30 percent for general purpose boards for use in dry conditions.
Current research was conducted to investigate the effect of combined modification of glutaraldehyde/paraffin on the physical properties of poplar wood. Impregnation was done in three concentration levels of glutaraldehyde, 5, 10 and 20% containing MgCl2 as catalysts, and consequently with paraffin in combined modified samples using vacuum-pressure method. According to the FTIR results, reaction of Glutaraldehyde with wood polymers resulted in increase the methylene groups and reduce the hydroxyl groups. Bifurcation of hydroxyl groups peak with increase of glutaraldehyde concentration from 10 to 20%, confirmed the hemiacetal formation that hydrolyzed faster than the acetal during soaking, so led to more weight loss. Glutaraldehyde modification was decreased water entrance into the wood structure via blocking of hydroxyl groups and cell wall bulking, and reduced the flexibility of wood for swelling due to crosslinking. Also, Paraffin by reducing the capillary effect, declined the penetration of water into the wood. Paraffin infixation in wood caused more weight loss of combined modification levels with increase of the immersion time.
In this study the effect of coating with lacquer (Shellac) on acoustic properties by forced flexural vibration in free-free beam in white mulberry (Morus alba) and walnut (Juglans regia) have been investigated. For this purpose, the samples of both species with dimensions of 2 × 15 × 140 (length, width, height) were prepared. The samples of both species for integrated humidity were kept in climatic chamber for three week in climatic chamber (20 ± 2C0 and 65 ± 5 % rH) and then the first step of forced vibration test for measure basic properties of the both test samples were performed on them. Aftter that the samples of both species were coated by lacquer and after integrated humidity in samples to assess the effect of lacquer on acoustic properties forced flexural vibrations test was performed on them again. The results showed equal variations in the specific gravity in both coated species in mulberry and walnuts samples. The modulus of elasticity, acoustic coefficient and acoustical conversion efficiency values after coating were reduced in both that drop in values in mulberry more than walnut species.The reason of this results caused with variations in the frequency and specific gravity of the test specimens in both species that variations in frequency in mulberry more than walnut species. Damping vibration values under the influence of coating was increasing in both species that's results obtained because the different influence of alcohol in withdrawal extractives in mulberry and walnut species and different nature and role of these substances in each species that mulberry that this factor values referred to in mulberry species was over than walnut species because of the different nature of the extractives in each species.
Cleaner production process is an environmentally friendly approach that attempts to reduce waste and energy consumption then reduce environmental pollutions of industrial processes to provide the possibility of sustainable production in industrial units. To achieve this goal and alignment with cleaner production strategies, paper industries should consider reducing wastes of production processes and irregular consumption of energy as a priority in their programs. In this research Analytic Hierarchy Process has been applied and a three level hierarchy model was structured to facilitate the cleaner production process in Latif paper products firm. Using a literature review and field study, the proposed model provided a framework for cleaner production implementation in the firm. Results showed priorities of the main criteria of cleaner production are process change, product modification, implementation of preventive maintenance system, resititution and man force capitals respectively. Process change criterion allocated 40 percent of the total weighing value and has the highest priority in implementation of cleaner production strategy. Existence of industrial automation and its technology level which is a sub criterion of process change has the highest priority among 31 sub criteria. Also some of higher priority sub criteria such as use of higher quality inclusion and implementation of calibration system are related to process change. Therefore, to achieve cleaner production goals and implementation of its strategic objectives it is necessary to pay more attention to this criterion. Inconsistency ratio of the research is 0.06 which indicates the results are compatible. The results of this research can be used to accelerate the implementation of cleaner production process in Iran’s pulp and paper industry.
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.
The aim of this study was to determinate the destructive behaviors of the white rot fungus Trametes versicolor on oak at different ambient temperatures and moistures. Hence, test fungus was collected from Khararod forest and after puricication, it was verified in the NCBI by molecular method. Thereafter, the wood samples were cut and exposed to fungus for mass loss determination at three temperature (10, 20, 30°C) and three relative humidity levels (45, 65, 85%) for 8 weeks. Destructive patterns of decayed wood sample was also examinate by microscopic method. The results indicated that a change in moisture content was more influential on destructive behaviour of fungus than temperature. Moreover, 20°C of temprature and 65% of relative humidity was the optimal environment for fungal activations. On the other hand, the microscopic investigations showed that Trametes versicolor produce simultaneous whit rot at all exposing conditions. Hence, it can be concluded that a shift in destructive behavior of this fungus which has already been reported is influenced by environmental factors other than temperature and moisture content
In order to Xylan extraction, bagasse pith, after alkaline pre-treatment and sodium chlorite bleaching, treated with different dosage of soda and then calculated extraction percentage and characterized with FT-IR. Produced xylan changed to xylose with diluted acid hydrolysis and after treatment with active carbon and ultrasonic, reduced sugar measured by HPLC. Then, obtained xylose was added to yeasts media of kluyveromyces marxianus and pichia stipites to evaluate its effects on their growth kinetic. Results showed that by increasing in soda dosage, xylan extraction percentage increased. Also, hydrolysis process alone can produced much sugar without active carbon and ultrasonic. Evaluation of yeasts growth kinetic showed that the speed of yeast growth in media including xylose was more than glucose one and so efficiency of these yeasts is much for C5 sugar as it can be used them for bio-products manufacture.
The purpose of the research is to examine the effect of nanoclay particles and compatibilization of oxidized polypropylene in molten phase on the mechanical and physical properties of wood-plastic composite made from polypropylene and phragmites ausralis flour. For this purpose, polypropylene in molten phase was oxidized in the vicinity of air oxygen and 1-dodecanol alcohol for 2 hours. Then Phragmites ausralis flour with the weight ratio 50% and the polymer phase was mixed with the compatibilizer at two levels (0 and 3%) and nanoclay particles at three levels (0,2, 4%) in an internal mixer for 6 min under the temperature 165 . Finally, the test specimens were prepared by using the hot press with the dimensions 150×150×2 mm. The mechanical and physical properties including tensile and flexural modulus and strengths, Non-izod impact strength, long term water absorption and thickness swelling were examined according to ASTM standards. The results showed that the using oxidized polypropylene as compatibilizer improves all physical and mechanical properties of the composite. They also showed that increasing nanoclay particles, the physical and mechanical properties of the wood-plastic composite improve, except the Non-izod impact strength. The structural studies of composite and the way the nanoparticles are distributed using x-ray diffraction spectroscopy and SEM images showed that the distribution of nanoclay particles in polymer matrix is of the type of intercalated structures.
For this purpose, 9 hornbeam trees at 400, 800 and 1100 meters altitude from forestry projects of Meshelak Nowshahr were selected. 324 Clear samples were cut at mature wood in diameter breast height (DBH). The prepared samples (dimensions: 2.5 × 2.5 × 41cm) in a room at temperature of 20 C and relative humidity (RH) 35, 65 and 95 % were conditioned. Afterward three weeks conditioning, at firs three points bending test for determining the maximum of bending load on 81 samples was done. 10, 20 and 30% maximum of bending load (MBL) were measured and then four points bending creep test for determining creep parameters on 243 samples at times period of 14 hours loading and 10 hours unloading in acclimatized room conditions were measured and then creep/recovery, creep modulus and relative creep were calculated.Results indicated that, the effects of load and relative humidity on creep parameters was significant so as the maximum and the minimum relative creep were observed in 95 and 35% RH respectively and the maximum and the minimum creep modulus were observed in 35 and 95% RH respectively. The maximum and minimum relative creep in 30 and 10% MBL respectively and the maximum and minimum creep modulus in 10 and 30% MBL were observed respectively. Results indicated that the increasing of bending properties caused decreasing the creep parameters.
In this research, the effects of poplar wood surface modification using sol-gel method on the quality of alkyd and polyurethane coatings for outdoor application were studied. For this purpose, the wood surface was modified with Tetraethoxysilane (T) sol-gel material. Then, solvent-borne alkyd (AS) and solvent-borne polyurethane (PS) coatings were applied. The quality of coatings was evaluated by microscopic observation using fluorescence, confocal laser scanning microscopy (CLSM) and EDX-SEM. The results of EDX showed a noticeable silicon peak in the sol-gel-treated specimens. The results of fluorescence microscopic studies showed that alkyd and polyurethane coatings only present in the cell lumens but the sol-gel penetrates into the cell walls. Laser microscope results showed that the modification of wood surface with sol-gel process reduces the roughness of alkyd and polyurethane coatings caused by weathering.
The purpose of this study is introduction new wood engineered products and predict their strength in combination with metal fasteners for timber structures construction. Investigation of steel dowel connections is an important issue that has attracted much attention today. There are many innovations in the constructions with the change in wood engineered products. For this research, a new combination of wood- based products was used; three layered structures consisted of birch plywood and OSB layers bonded by a single- component Polyurethane resin in four configurations. The connections used in this study were steel dowels in 6 mm and 8 mm diameter. After producing new layered products, the embedment strength of samples was evaluated and compared to amounts calculated by engineering functions of resistance prediction according to EC5. Results showed that, the effect of the layered composition type on the embedment strength of connection was significant as well as the steel dowel diameter. Increasing of dowel diameter improved the embedment strength of materials. The compound with more contribution of plywood had higher embedment strength. The important point and purpose of this study was the evaluation of the ability of EC5 in prediction of new engineered wood product strength, which reveal that the behavior of four material types could be predicted by EC5 with a sufficient accuracy and all material types had strength without failure occurrence and according to prediction.
This paper investigated the radial variations of acoustical and mechanical properties of date palm from the pith to the bark. Cubic samples with dimensions of 2×2×35 cm3 (Radial× tangential ×longitudinal)) were taken in distance of 3, 6, 9, 12 and 15 cm toward the bark. To evaluate dynamical properties of date palm, flexural vibration method was applied on cubic experimental samples. Further the specimen then were utilized for measuring MOE and MOR in static bending test. More details were also attained by anatomical analyzes. The results showed that the acoustical parameters of the propagated wave (the internal friction, the acoustic conversion efficiency as well as the acoustical impedance) were constant while increasing the distance between pith and bark. The highest values of acoustic coefficients found for samples near the pith and partially increased while moving to the bark. The density variations were less important in radial direction of date palm disk. The MOE and MOR values significantly radially varied and were maximum for samples in distance 3 cm. As they reached to the distance of 15 cm from the center, the given parameters dramatically decreased. Finally it can be conclude that the quality assessment of date palm based on the acoustical parameters is not reliable. It is suggested to provide samples from the outer parts of date palm disk when construction materials need more strength.
AbstractThe aim of current study is to determine the physical and mechanical properties of wood-based composites commonly used in Iran’s market before and after accelerated aging. Accelerated aging process performed based on ASTM D1037. Specimens of particleboard and medium-density fiberboard (MDF) made of wood and bagasse obtained from various factories. Physical properties including density, water uptake and thickness swelling (after long-term water soaking), and mechanical properties including flexural strength, modulus of elasticity and internal bonding before and after aging. The most density loss observed in MDF after aging, while particleboard specimens were less damaged. Water absorption and thickness swelling of MDF specimens were less than those of particleboards during long immersion, due to the smoother surface and lower permeability. After aging, water uptake and swelling increased in all boards due to hydrolysis of resin and bulking the boards. After aging process, highest reduction in flexural strength and modulus of elasticity observed in MDF although a significant reduction observed in particleboard. Internal bonding of specimens were higher than standard level before aging process; but after aging decreased significantly, due to hydrolysis of resin in alternating drying-wetting conditions.
This research is aimed to investigate the possibility of making resistant Light concrete and the effects of different levels of wood and silica particles on physical, mechanical and morphology was performed. Granulation wood particles to 5 levels, 0, 5, 10, 15 and 20% and silica particles in a scale of nanometers and micrometers to 4 levels, 0, 3, 6 and 9% based on dry weight of cement were the variables of this research. Mixing process was is done manually and cement paste produced into a square molds were cast. To amass gel of cement was used from the vibrating table. After making concrete physical properties including water absorption, moisture diffusion coefficient and density in accordance with ASTM standard and mechanical properties including compressive strength and compressive strength index accordance with the regulations for concrete Iran (ABA) was performed. Infrared spectroscopy to evaluate the impact of silica particles were made of concrete. Scanning electron microscope to study the morphology of concrete were used. The results showed that by increasing the amount of wood, density, compressive strength and compressive strength index decreased while water absorption and moisture diffusion coefficient increased. Silica increases to 3 percent, increased compressive strength and compressive strength index and addition of more silica have a negative impact on the properties. Water absorption of samples by adding silica to 3 percent decreased and then increased. Density of samples increased with increasing silica. With increasing of silica to 3 percent, moisture diffusion coefficient was decreased but then the moisture diffusion coefficient increased with increasing silica. Infrared spectroscopy showed that addition of silica peak was reduced to a hydroxyl group. The results of scanning electron microscope showed good distribution of silica particles on the surface of 3 percent.
In this study, variation in screw diameter and corresponding pilot hole, and relationship between these variables with withdrawal resistance for establishing multiple linear regression model was investigated. In this investigation 9-ply LVL was made of poplar (Populus deltoids). LVL was produced with polyvinyl acetate adhesive. Test specimens were prepared from LVL produced with dimensions of 7.5 * 7.5 cm. Dimension of pilot hole embedded in specimens at 4 levels (50, 60, 70 and 80 present of nominal screw diameter). The test Specimens were studied with nominal screw diameter 4.2, 5, 6 and 7mm were produced. Withdrawal resistance of screw was tested from surface and, edge and cross-sections. Results have shown that withdrawal resistance from edge (perpendicular to grain) was more than withdrawal resistance from face and cross-section (parallel to grain). Also the results have shown that withdrawal resistance of different screw diameter decreased with increase of pilot hole diameter, but withdrawal resistance increased with increase of screw diameter itself. The highest withdrawal resistance was obtained from screw 7 mm in diameters and predrilled hole diameter 50% of screw diameter. The lowest withdrawal resistance was observed from screw 4.2 mm in diameter and predrilled hole diameter 80% of screw diameter. Finally multiple linear regression models ys= 3.055+.411X1-3.358X2, ye║=2.6361.694X1+.089X2 and ye┴= 2.334+.509X1-2.901X2 were obtained to predict of withdrawal resistance for face, cross-section and edge respectively.
