مجله صنایع چوب و کاغذ ایران
سال هشتم شماره 2 (تابستان 1396)

Considering the increasing consumption of wood and wood products in Iran and limited domestic sources of wood and shortage of wood raw material in Iran, wood raw material imports is a solution for Iranian developing wood industrie's wood procurement.
But, wood imports to Iran, always faced with a lot of challenges. The aim of this research is to determine and evaluate the challenges in the way of wood imports to Iran. The research method used in this study is a descriptive-analytic method. The analytic method used in the study to evaluate the challenges is the Fuzzy Delphi Analytical Hierarchy Process (FDAHP). First the findings of previous researches in the field and the literature were studied and doing interviews with industry experts, the challenges in the way of wood imports to Iran were extracted and classified in 5 groups and 35 factors and were evaluated.
The results shows that in the first level (groups) the regulation, economic, politic, infrastructure and management groups have the most importance respectively. In second level (challenges), plant protection regulations have the most importance. After that, exchange rate tolerance, oil income, banking support and GDP have most importance respectively.

This article aims to facilitate the use of methyl cellulose adhesive to repair paper works that its ink is sensitive to water. This research is conducted by analytical comparisons method and samples is collected by experiments related to research topics such as pH measurement, Calorimetric, infrared spectroscopy with total attenuated reflection (FTIR- ATR), the measurement of tensile strength as well measurement of The adhesive strength of the samples. The stages of this study is conducted so that the adhesive methyl cellulose at a concentration of 7% in methanol was prepared. The prepared specimens is treated under Temperature-humidity accelerated aging in accordance with standard ASTM D4714-96 no for 384 hours and under light in accordance with ASTM D6789-02 for 360 hours and Changes of color, pH, tensile strength and adhesion is investigated for them. Results showed that the samples pH is changed from 6.91 to 6.39 after light aging and to 6.06 after temperature-humidity aging. Also, Tensile strength of Samples is reduced from 0.31 to 0.23 kN per meter after light aging and to 0.24 kN per meter after the temperature-humidity aging. Also, the adhesive strength of the samples is decreased from 1.43 to 0.97 Newton after light aging and to 1.51 Newton after temperature-humidity aging.

The aim of this study was to investigate the effect of using recycled polyethylene on the mechanical properties of PE-MDF composite. Saw dust as a filler at 30%and MAPE as coupling agent at two levels of 0 and 2 wt% were mixed in an internal mixer and the samples were prepared by injection molding method.. Mechanical properties such as tensile and flexural (Strength and Modulus) were measured. Morphology of composite was also evaluated by scanning electron microscopy (SEM). Although virgin polyethylene has better mechanical properties than once and twice recycled polyethylene, but with the addition of sawdust as filler consisting of recycled polyethylene composites mechanical properties significantly higher than that virgin polyethylene. The results of mechanical properties showed improvement by the addition of MAPE. The SEM micrographs showed that the use of twice recycled polyethylene and MAPE has led to better interactions between matrix and filler. The melt flow index (MFI) indicated that with increasing number of recycled polyethylene, melt flow index increased. Therefore with attention to the results of mechanical properties can be stated that by increasing the melt flow index had a positive effect on composite construction.

The purpose of this study was to evaluate the physico-mechanical properties and formaldehyde emission of medium density fiberboard (MDF) made from modified urea formaldehyde resin. In this study, nanocrystalline cellulose (NCC) (0, 0.5, 1, 1.5 and 2 percent) based on the dry weight of resin was applied to modify urea formaldehyde resin. The results of mechanical properties indicated that MOR and IB of the MDF panels significantly increased as the NCC incorporated into the UF adhesive up to 1%wt. However, further increment in the NCC content (1.5 and 2 wt%) decreased the MOR and IB of the panels. Water absorption and thickness swelling after 2 h were significantly increased when the NCC content increased from 1% to 2%, but no significant differences were observed between the panels after 24 h. Also, the formaldehyde emission significantly decreased with increasing the amount of nanocrystalline cellulose.

In this study, the effect of cellar fungus (brown rot fungus) conophora cerabella on biodegradability, hardness and dimensional stability of wood flour/polypropylene/glass fiber hybride composites after suffering ambient conditions (immersion in water) were studied. So, the samples by 40 to 60, 50 to 50 and 60 to 40 percent of wood flour / PP weight ratios respectively and three levels of glass fibers 0,10 and 15 weight percent were made. The Samples, immersed in water at 25 and 40°c, sea water and pool water for 1608 hours and then exposed to the cellar fungus for 6 weeks. The results showed, by increasing the wood flour weight ratio and Adding glass fiber to composite samples, those weight loss due to fungal attack, increased and decreased respectively. Overall, after immersion in water compared to control, the samples had greater weight loss and the samples that immersed in pool water and hot water of 40°c, compared to others, showed greater amounts of weight loss. With the increase of wood flour weight ratio and adding the glass fiber in hybrid composite, the samples hardness were increased. Overall, after soaking in water, compared to controls, the test samples showed lower hardness. By increasing the wood flour ratio in composites, the water absorption and thickness swelling amount, were increased. Adding glass fiber to composites in all ratios of wood flour, caused to reduction and controlling of water absorption and thickness swelling.

Non-destructive testing of materials properties is continuously developing. Ground penetrating radar (GPR) as a non-destructive method is based on the transmission of electromagnetic energy and recently has been applied in field of wood and wood products. In this study, GPR technique was used to evaluate the internal defects in three species hardwood with three moisture content levels. In order to remove determinant extrinsic and uncertain factors, several artificially defects were created within the wood samples. Data collection was done by MALA CX GPR in center frequency of 2300 MHz and processed with Reflexw software. This study showed that dielectric properties on wet-woods are more than that in dry-woods and internal defects woods in wet wood can be detected better than dry woods. However, the holes with diameters of 4 mm and less were not detectable. In general, GPR, as a safe and portable method, is capable for detecting internal defects and voids in hardwood.

Increasing use of wood products accompanying with resource constraint has revealed the importance of nonwood based material. In this study, pulping and papermaking potential of three varieties of weeds including Xanthium spinosum, Carthamus tinctorius and Cyperus papyrus have been considered. At first, chemical components of the samples i.e. cellulose, lignin and extractives have been measured following TAPPI standard test methods. Afterwards, pulping process based as soda and Kraft has been carried out and the pulp properties i.e. screen yield and reject, kappa number, caliper, bust index, tear index, brightness have been considered. According to the results, the amount cellulose, lignin and extractives have been measured for the Xanthium spinosum %38.15, %13.5 and 4.72, respectively. Theses parameters have been estimated about %38.25, %10.3 and % 2.95 for Carthamus tinctorius and %38.8, %19.2 and 4.4 in case of papyrus. The yield of soda and Kraft pulp of the papyrus was more than Xanthium spinosum and Carthamus tinctorius. Among all treatments, the highest screen yield related to soda pulping of Cyperus papyrus by %39.8 which has been obtained by 175 centigrade as a maximum temperature, L/W: 6/1, active alkaline: %30 and 90 minutes as the time at temperature. The lowest and highest amounts of the tear index were related to soda pulp sample of the Carthamus tinctorius and Kraft pulp sample of Xanthium spinosum by 2.49 and 8.1, respectively. In addition, the lowest and highest amounts of the bursting index were related to soda pulp sample of the Cyperus papyrus and Kraft pulp sample of Xanthium spinosum by 0.61and 2.48, respectively. Meanwhile, soda pulp sample of the Cyperus papyrus showed the highest amount of brightness with %45 ISO.

Natural composites with biodegradability properties can be used as a renewable alternative to replacing conventional plastics. Thus, to reduce the plastics applications in the packaging industry, biocomposites content of wheat straw (with 40, 100, 140 mesh) as a natural biodegradable composite and low density polyethylene (LDPE) as a common synthetic polymer in the packaging industry were prepared and characterized by the mechanical and water absorption properties. Polyethylene-graft-maleic anhydride was used as a compatibilizer material. Morphology of wheat straw flour was studied by optical microscope to obtain the aspect ratio (L/D). The tensile and flexural tests were applied for determining mechanical properties and scanning electron microscope (SEM) was used for particles distribution and sample structures. The water absorption of the samples was calculated by weight difference. The results indicated that the particle size of wheat straw four and the L/D amount are Significantly affected on the tensile strength and water absorption of the samples. However, the effect of wheat sraw particle size on the flexural strength was not significant. Overall conclusions show that by increasing the particle size of the filler (wheat straw), can prepare the biocomposite with better tensile strength and less water absorption compared with smaller particle size.

In recent years, much attention has been paid to nano technology for improving wood defects. Wollastonite as a mineral is commonly used in the production of plastic, ceramic and concrete. Wollastonite production in nano scale has increased interest in using it. Recently, a large number of studies have been carried out in Iran aiming to improve durability, dimensional stability, and flammability of wood and wood products using nano wollastonite. Based on the promising results obtained in these researchs, this study was conducted as a complementary investigation to verify nano-wollastonite penetrability into the wood as well as its effects on biological durability and dimensional stability. The results showed that nano-wollastonite could not penetrate into the xylem since wood texture serves as a filter against it. The treated samples with nano-wollastonite showed partly resistance against white rotting fungus, but this was lost after a short-time leaching. Nano-wollastonite had no effect on the water absorption and volumetric shrinkage of treated samples. Base on the results of this study, nano-wollastonite is not recommended for wood impregnation industry, at least when raw wood is concerned.

The objective of this work is to investigate the use of PCC, and the impact of its coating weight on paper coating. In this study, two base papers from Mazandaran Wood and Paper Industries (APC and NS), and two coating compositions with the solid content of 25% containing PCC filler (100 parts), PVA binder (14 parts) and dispersant (1 part) were used. The first composition included PCC B102 for opacity increment, and the second one PCC 9020 for the improvement of brightness. Two rod RDS14 and RDS30 were used for different coating weights. After coating, the treated samples were dried in room conditions at air temperature of 25◦C and relative humidity of 54%. Physical and optical properties of control and treated samples such as air resistance, thickness, Cobb60, brightness, yellowness, opacity and roughness were determined. In comparison to the control group, all the treated samples showed improvement in brightness, opacity, yellowness and air resistance. By the two different formulations and two rods, paper roughness was increased, and the increment of water absorption was due to capillary development in coating texture. The analysis of variances showed that the usage of PCC 9020 had considerable effect on roughness of papers. In NS papers, change of PCC caused significant difference in brightness and roughness, but in APC papers did not. The change of coating rod in APC papers had significant effect on water absorption, brightness and opacity but did not show in NS.

In this study 3D stress-strain distribution of dowel and glue line on L-type joints made of plywood doweled was investigated. Members of joints made of 11-ply hardwood plywood (Hornbeam, Beech and Alder) that were 19 mm in thickness. In this study effect of beech dowels in three levels diameters (6, 8 and 10 mm) and penetration of depth (9, 13 and 17 mm) on bending moment capacity of L-type joints under compression loading was investigated as experimental test, then stress-strain distribution of wood dowel and glue line in specimens were simulated by means of ANSYS 15 software with finite element method (FEM).Results have shown that bending moment resistance increased with increasing dowel diameter from 6 to 8 mm, but downward trend was observed with increasing 8 to 10 mm in dowel diameter. Bending moment resistance increased with increasing penetration depth. Also, result obtained of simulation by means of ANSYS software have shown that stress-strain in dowel and glue line increased with increasing diameter of dowel and Increasing stress in joints made of diameter dowel 10 mm due to fracture in joints and decrease in resistance once. According to results obtained of model analysis, the ultimate stress of dowel and glue line occurred in the area that joints were contacted.

The remaining the logs in the stump area and especially along the forest roadside, can increase the check in the caused by growth stress in the both sides of log. All of these factors led to a decline in the quality of the logs, which can be lined up in the ends of log with suitable coating materials such as end coating and anti-checking iron treatments to prevent log checking. A field-based study was performed to study the effects of end coating and anti-checking iron treatments on prevent log checking in beech and hornbeam logs in Gorazbon district in Kheyrud forest northern Iran. In this study, 180 logs were randomly selected from two spices; beech and hornbeam and for any spices, 30 logs were selected for anti-checking iron treatments, 30 logs for paraffin treatments and 30 logs for control. Duncan’s test showed that in the hornbeam logs anti-checking iron treatments was the lowest checking increase comparing the paraffin and control treatments and this difference was statistically significant. Duncan’s test showed that in the beech logs anti-checking iron treatments was the lowest checking increase comparing the paraffin and control treatments. It can be concluded that the lowest check has been shown in the anti-checking iron treatments in two beech and hornbeam logs and this treatment has the greatest role in preventing ends check in compare with the paraffin treatment.

In this study, fibers recycled via two different methods; hydrothermal and ohmic heating were used to manufacture medium density fiberboard (MDF). The purpose of this study was to determine the effect of recycling method on practical properties (bending strength, modulus of elasticity, internal bonding and screw holding in edge and surface and thickness swelling after 24 hours water immersion) of the boards. Also, a morphological analysis was done to evaluate the influence of recycling process on fiber dimensions. Also the existence of UF residues were observed by SEM.
The results related to classification and dimension analyze of fibers confirmed the negative influence of recycling process on quality of fibers. Also degree of deterioration in hydrothermal recycling was higher than that of ohmic recycling due to sever condition of heating.
Furthermore, the results showed that recycling of MDF wastes via ohmic heating method resulted in better physical and mechanical propertied as compared to the hydrothermal method. Overall results showed that MDF panels made from recycled fibers via ohmic heating method exceed the minimum values required by EN standards (EN 622-5, 2006) for all properties except thickness swelling. About ohmic heating method, increasing the time of ohmic heating led to improving the practical properties of recycled MDF boards. It was observed by SEM that much more residues of cured UF resin adhesive were existed on the surface of recycled fibers via hydrothermal method. According to the results it can be said that ohmic heating method is a useful process for recycling the wastes of MDF.