مجله صنایع چوب و کاغذ ایران
سال ششم شماره 2 (پاییز و زمستان 1394)

In this research the effect of pressing conditions were studied on the green and environmentally friendly, particleboard made of natural mimosa condensed tannins adhesive. Pressing temperature at 200 ° C was fixed. The press time in four levels 3, 4, 5, and 7 minutes and press pressure at three levels of 15, 18 and 22 kg/ cm-2 were considered as variable factors. The results showed that the best treatment from internal bond strength and thickness swelling viewpoints is where pressing conditions include a pressure of 18 kg cm and 5 minutes. In this status, the internal bond 0.59 MPa was obtained and thickness swelling was the lowest compared to the other treatments. It was found that the water absorption decreased with increase in pressing pressure untill 22 kg/cm2.

Nowadays, many of developing countries are looking for outsourcing opportunities of developed countries, because this will bring them many benefits. In this regard, the goal of this study is determining and prioritizing of the effective criteria on attainment of outsourcing benefits of the developed countries in wood furniture industry by non-parametric approach of analytic hierarchy process as one of the most creditable multi-criteria decisionmaking methods. For this purpose, after comparative studies and interview with relevant experts, the effective criteria were identified. After design of analytic hierarchy levels of decision making tree, the necessary data for prioriting provided by standard questionnaire based on paired comparisons and finally the computational steps was done by Expert Choice software. Base on the obtained results, currency exchange rate, economical stability, inflation rate, labor cost, cost of raw material, technological software and hardware of furniture industry, skillfull manpower and developed lateral industries, have the highest priorities.

In this investigation, the potential of flexural vibration method as nondestructive tool was studied in order to evaluate the acoustical and the mechanical properties of bagasse composites. For this purpose, more than 40 cubic samples (36×4×1.6 cm3) were taken from the given materials. The results showed that the acoustical behavior of particle board were better than that measured for medium density fiber board. In MDF samples, the resonance frequency, the sound velocity, the quality factor as well as the acoustic coefficients were significantly lower than those measured in PB samples. In contrast, the internal friction measured in MDF was greater than values of PB. But no significant difference was observed of ACE in both MDF and PB samples. The young's modulus of MDF and PB were obtained by conducting a flexural vibration method under the free- free condition based on Timoshenko's vibration theory. The results were also compared with the modulus of elasticity and rupture calculated by 3 point bending test. The modulus of elasticity values, measured by dynamic method were 15% and 6% higher than those achieved by static bending method for MDF and PB respectively. It was also illustrated that the modulus of elasticity and the sound velocity were significantly positively related to the density of MDF and PB while the other acoustical properties had negative relations with density. As good correlations were found between dynamic and static modulus of elasticity (0.71) and also static modulus of rupture and dynamic modulus of elasticity (0.44), it can be drawn that the flexural vibration is valuable tool in order to evaluate mechanical properties of MDF made by bagasse while the same results were not observed in PB composites.

In this study, physical and mechanical properties of poplar (Populus nigra) plywood made by urea-formaldehyde resin along with nano fiber cellulose were studied. For this reason, the nanofiber cellulose as filler at five levels 0, 1, 3, 5 and 7% based on oven dry weight of resin were used. Physical and mechanical properties of the samples, including water absorption and thickness swelling after 2 and 24 hours immersion in water, bending strength and modulus of elasticity (parallel and perpendicular to surface grain) and bonding shear strength were measured. The results showed that increasing the amount of nano fiber cellulose improved the dimentional stability of the boards. Also increasing the amount of nano fiber cellulose increases the bending strength and modulus of elasticity parallel to surface grain. On the other hand, increasing the amount of nano fiber cellulose increases the bonding shear strength but no significant differences observed between the different treatments.

The present study carried to investigate physical and biometry properties of Evonymus latifolia wood. For this purpose three normal of trees were selected from Chamestan-Nour city of Mazandaran province. Three log-5 cm thicknesses were taken at 1.30, 3 and 5 meter from each tree. Three samples position were prepared along radial position from the pith to the bark. Then physical properties (basic density and volumetric shrinkage), biometry properties (fiber length, fiber diameter and cell wall thickness) and morphological properties (slenderness, Runkel, flexibility, rigidity coefficients and Luce's shape) were determined by SPSS software. Analysis of variance (ANOVA) indicated that the effect of longitudinal and radial postions had significant differences on the volumetric shrinkage, fiber length, fiber diameter and cell wall thickness. There is a significant difference among samples of radial position in basic density. The physical and fiber diemnsions along vertical direction from bottom to upward of trees were decreased. With increasing of cambial age, the amount of basic density, volumetric shrinkage, fiber length, fiber diameter and cell wall thickness were increased. The averge of basic density was 0.558 g cm-3, the volumetric shrinkage 18.21%, the fiber length was 1.316 mm, the fiber diameter was 25.02µm, the cell wall thickness was 7.24 µm, the slenderness coefficient was 53.19, the flexibility coefficient was 42.06%, the runkel coefficient was 1.41, the rigidity coefficient was 28.96% and the luce's shape pe was 0.698.

This study was designed to investigate the effect of modified iron oxide nanoparticles (MINP) and cellulose nanocrystals (NCC) on magnetic, thermal and dynamic-mechanical properties of poly(vinyl alcohol) based nanocomposites. Fe3O4 nanoparticles have been synthesized using a chemical co-precipitation route. Nanocomposite films were developed by solvent casting method and their properties were characterized by vibrating sample magnetometer (VSM), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). DSC results found that with incorporation of nanoparticles, the glass transition temperature increase slightly to higher temperatures; however, the degree of crystallinity and the values of the melting temperature are found to decrease. Dynamic mechanical analysis revealed that, at the elevated temperatures, improvement of mechanical properties due to the presence of nanoparticles was even more noticeable. Addition of nanoparticles resulted in increased thermal stability of PVA due to the reduction in mobility of matrix molecules by strong hydrogen bonds between nanocomposite components. Results indicated that, MINP and NCC have synergistic effect on improving of poly(vinyl alcohol) properties. The VSM findings showed that the saturation magnetization of iron oxide nanoparticles reduced after modification. This can be attributed to formation of hydroxyapatite on nanoparticles surface. The saturation magnetization (Ms) of PVA- MINP films was higher than PVA-MINP- NCC film. This result probably is related to more amount of magnetic nanoparticles in PVA-MINP films.

Nowadays there is a great competition for the production of packaging paper from recycled fibers. But success in this competition depends on improving its strength properties. Thus when it comes to talk about recycled fiber, the first and most important challenge is to tailor it for pulp and papermaking. Quantitative and qualitative papermaking information of recycled papers will significantly help to achieve this objective. Therefore in current research, some of papermaking parameters such as: fiber length average and distribution, the kind and amount of pulp and also the existing quantity of starch in OCC pulp were studied. The results showed that its fibers length has uneven distribution and more than 85% of OCC fibers have the average length less than 1 millimeter in the range of 0.47-0.65mm. Undoubtedly, this uneven fiber length distribution and its low length average would decrease the strength properties of paper. Fiber staining analysis applying Graff ″C″ stain represented that main section of fibers approximately 72.91% is from kraft pulp, and mainly softwood resources (33.33%). Moreover, the amount of extracted starch was measured nearly 2.32±0.25%. It should be considered that in recycling process, this amount of starch can strongly affect the chemical charge balance in wet end section of paper machine.

In the present research , the effect of utilizing a mixture of Birch with Hornbeam & Beech species (in the comparison with sample CMP( 75% Hornbeam 25% Beech) , on the mechanical and optical properties of papers produced within the domain of Freeness degree (CSF) of 300 ml and 85% yield has been reviewed . The CMP was prepared in accordance with 85% yield condition , different cooking times (30-120 min) , temperature of 170°C and white liquor ratio to chips in 7 to 1 & 20% Sulfide based on chips dry weight at 4 levels of 10, 20, 30 & 100% Birch mixed with Birch and Hornbeam species. After defibration and preparation of 60gm hand sheets, the optical and mechanical properties of that were assessed. The results indicated that by increasing the percentage rate of Birch , the quality of the manufactured paper was also increased and the best strength and optical properties were related to the 30 & 100% consumption rates of Birch in mixture with Beech and Hornbeam species.

In this study, the effect of different drying methods on cellulosic nanofibers and resulting composites investigated. Four methods were examined to dry nanofibrillated cellulose suspensions: air drying, oven drying, spray-drying and freeze drying. The particle size and morphology of the CNFs were determined via dynamic light scattering, scanning electron microscopy, and morphological analysis. Freeze drying formed ribbon-like structures of the CNFs with nano-scale thicknesses. Width and length were observed in tens to hundreds of microns. Spray-drying formed particles with a size distribution ranging from nanometer to several microns. Spray-drying is proposed as a technically suitable manufacturing process to dry CNF suspensions not only with dimension in nano range but also improving mechanical properties of poly (lactic acid) based composites.

In this paper a new method is introduced for defect detection in veneer images to investigate wood quality. In this method firstly, separating of defects from natural background of veneer is modeled a hypothesis testing problem. In the next step, the natural texture of veneer is eliminated by using morphology concept. Finally the correct boundaries of defects are extracted by optimizing energy function on above homogen area. Performance of the proposed algorithm is evaluated on real captured images containing several kinds of surface defects. The results demonstrate that the proposed method detects the defects approximately 18% better than some present approaches. Furthermore, it may be shown that better detection of defects in the proposed algorithm not only does not lead to extracting more false defects, but also it decreases rate of false detections approximately 8.2% compared to the existing algorithms. Consequently, it may be concluded that the proposed method may be used as a suitable alternative for detecting defects in veneer surfaces.

In order to develop the structural applications of natural fiber-polypropylene composites, achieving enough knowledge about their mechanical behavior is necessary. One method for describing flexural characteristics of a flexural section is using the moment-curvature analysis which is an alternative for stress-strain relationship in many analyses. In this study the effect of temperature on natural axis position and flexural stress distribution in section of flexural test specimens was investigated using a moment curvature analysis method. Flexural, tensile and compressive tests were conducted in temperatures ranging from room temperature to 80 oC. A FORTRAN program was used for analysis of moment-curvature in flexural section of flexural test specimens. In order to verify the results of the program, the predicted load-deflection and maximum moment data obtained from the program were compared with the experimental load-deflection and maximum moment data and results showed that the program was able to describe the flexural behavior of the studied composite. Results showed that non-uniform flexural stress distribution led to moving up the neutral axis toward compressive side. Also with increasing temperature, the balance between compressive and tensile strain is maintained with shifting the neutral axis to compressive side, and with elevating temperature, the movement of the neutral axis decreased.

Matairesinol lignan (MR) of Arizona cypress was isolated, characterized and purified. Wood flour was pretreated with hexane to remove the lipophilic moieties and then soaked in ethanol-water (9:1 v/v) to isolate the phenolic extractives. Matairesinol fraction of the extractives was purified with potassium acetate. Identification of extract moieties were performed using gas chromatography-mass spectrometry (GC/MS). Analyzing the unpurified extractives indicated the presence of aromatic and sugar impurities within the extract. The results showed that purification of the isolated extractives with potassium acetate led to the reduction of the impurities. In addition, the amount of MR lignan in the original ethanol extract, sediment and clear solution after centrifugation was determined as 11.3, 32.59 and 40.44%, respectively.