Iranian Journal of Wood and Paper Science Research
Year:2017 | Volume:31 | Issue:4 (57) |Papers Count:18

In recent years, there has been a considerable attention on producing and using renewable and environmental friendly cellulose film and coatings. In respect to the application of these films and coatings in different industries such as food, packaging and medical industries, the antimicrobial property such films and coating is an important issue. . The purpose of this research has been the production of cellulose based antibacterial film. First, long fiber pulp was converted to NFC using a supergrinder and then nanosilver treated films were prepared applying silver nitrate using two different methods. In the first method, silver nanoparticles at either 5 and 10 ppm dosage were reduced on NFC particles’ surface using retention aid. In second method the prepared NFC film was immersed in a solution of silver nanoparticle having the concentration levels of 5 and 10 ppm. At higher concentration of nanosilver solution, the retention Ag nanoparticle in the first method was higher than the second method whereas, at lower concentration, the differences of retained nanosilver between two methods was not extensive. It worth to mention that immersion method shows the benefit of avoiding Ag nanoparticle to be drained during pulp dewatering and nanosilver solutions could besimply reused.

The aim of this study has been the utilization of recycled polyethylene for modification of physical and mechanical properties of particleboard. Therefore, three levels of resin content ( 10, 7 and 4% ) and three levels of recycled polyethylene (content 5, 10 and 15% in surface layer of mat) were used in particleboard production. . Also three boards with 10% resin content in surface layer and without polyethylene were produced as control samples. The physical and mechanical properties of boards were measured and analyzed. The results of this study indicated that with increasing the recycled polyethylene content, the MOR, MOE and thickness swelling of boards were improved significantly and the boards with 15% recycled polyethylene compared to control boards showed 59 and 53% improvement respectively. Also the results revealed that the water absorption of boards decreased with increasing the recycled polyethylene content, and the minimum water absorption was observed in the boards with 15% recycled polyethylene. Based on the results of this research and considering the increasing of polymeric residues in the environment, the utilization of recycled polyethylene in particleboard production provide multiple advantages.

In this study, the possibility of using ash and sour orange tree bleached CMP pulp as replacement to CMP pulp produced in Mazandaran Wood and Paper Industries (MWPI) in the production of newsprint was investigated. For this purpose, first, ash and orange tree wood CMP pulps were prepared using cooking conditions of MWPI, (sodium sulfite white liquor at 101 gr/lit Na2O, yield 85%, 160 C cooking temperature and 75 minutes cooking time). Then the CMP pulps were bleached with hydrogen peroxide, and mixed with 15, 30, 45 and 60 percent of MWPI bleached CMP pulp and compared with MWPI bleached CMP (control sample). 60 gr/m2 handsheets were prepared and the optical and mechanical properties of the handsheets were measured and the data were analyzed and compared. The results showed that newsprint from ash CMP pulp was more suitable than CMP pulp mill in all measured properties (except brightness) and sour orange tree CMP pulp (except opacity). Following bleaching with hydrogen peroxide, the brightness, tear, burst, tensile strengths and breaking length were increased and opacity decreased. The results showed that ash and sour orange tree pure unbleached CMP pulps do not exhibit suitable properties for newsprint production and these pulps need to be bleached with hydrogen peroxide. The optimum mixture of the pulps are 45-60 percent from either ash wood pulp or sour orange tree bleached CMP pulps with 40-55 percent MWPI CMP pulp for newsprint production.

Nowadays, the leading experts of the world’ s furniture industry aknowledge the presence and potentials of Iran furniture industry and more importantly, they believe i Iran furniture industry can advance and grow much more in the future. So, the purpose of this paper is to investigate the domestic living furniture producer’ s point of view on manufacturing and selling of these products. In this regard, information from competent academic specialists was collected. Then five indices affecting the production and sell of furniture was determined and used in the form of a standard questionnaire. In order to check the validity and reliability of the survey, Cronbach’ s alpha coefficient and content validity methods were used respectedly. Ultimately, rating the indices by Leikert method showed that customer focus, collaboration with the academics, imported furniture, design and finally producer’ s satisfaction of government and business support respectedly had the most to least degree of importance for domestic living furniture producers' to the way they manufacture and sell the furniture products.

The current research work was planned to investigate the possibility of zinc oxide nanoparticles synthesis using hydrothermal method in the wood structure and to determine its effect on mechanical and biological properties of wood-polymer composite. Test samples were divided to control and treated with styrene, zinc oxide nanoparticles, nanocomposite and nano/styrene. Mechanical and biological tests samples were treated according to ASTM-D 143 and EN 113 respectively by vacuum-pressure method using experimental cylinder. The mechanical and biological tests for each level were conducted at5 and 10 replicates, respectively. The presence of zinc oxide nanoparticles on the cell wall and styrene in the cell cavities were confirmed by Scanning electron microscopy. According to the results, the bending strength, bending modulus, hardness and compression strength parallel to grain for nano/styrene samples were 36. 74, 40. 23, 60. 58 and 25. 07 percent higher than control samples, respectively. Also, decay resistance of treated samples increased, so that maximum and minimum weight losses were recorded for control and nano/styrene samples at 25. 81 and 3. 37%, respectively.

In this study, the mechanical and biological properties of poplar wood modified with glutaraldehyde and paraffin were investigated. Modification was performed at different concentrations of glutaraldehyde, (5, 10 and 20%) using magnesium chloride as catalyst and then subsequently with paraffin by vacuum-pressure method. High glutaraldehyde concentration increased the weight gain and cell wall bulking, subsequently reduced paraffin penetration into the porous structure of wood. Biological resistance exposed to white rot fungi and mechanical properties were measured according to the EN113 and ASTM D143 test methods, respectively. Scanning electron microscopic images showed bulking of cell walls and the presence of paraffin in cell cavities. According to results of TGA, increasing of modification intensity decreased mass loss due to cross links formation between glutaraldehyde and cell wall polymers. Paraffin at combined modification containing 10% and 20% glutaraldehyde improved significantly the modulus of elasticity. Glutaraldehyde reduced bending strength, but paraffin improved this property in the modified samples. Glutaraldehyde increased compression strength parallel to grain and hardness and the improvement was more apparent in combined modification. Glutaraldehyde modification enhanced decay resistance for samples exposed to white rot fungi, and it showed a significant increase at the presence of paraffin. The improve of the resistance of chemically modified wood exposed to white rot fungus can be attributed to the reduction of wood moisture, bulking of cell walls and cell cavities blocking.

The present research was carried out to find the stress-carrying capacity of corner miter Vjoints in tensile and compression directions to be compared with those of dovetail joints. Variables included the type of material to produce the joints (MDF and particleboard), the number of V-nail in each joint (2, 3, and 4 V-nails), and the height of V-nails (7 and 10 mm). Separate sets of joints were produced with and without polyvinyl acetate resin. Results demonstrated that the stress-carrying capacity under compression was significantly higher than those in the tensile direction. Moreover, MDF joints showed higher stress carrying capacity in comparison to those made from particleboard. Joints with resin were significantly stronger than those without resin. Higher number of V-nails resulted in improvement in the stress-carrying capacity in both directions. Based on the results of the present research, it was concluded that V-nails are preferred to dovetail joints from different perspectives, including their lower production cost, lack of need for an extra step to mill the joint to inset the bits, fast and easy installation of V-joint in one-step process, as well as higher stress-carrying capacity. The results indicated the maximum stress-carrying capacity of 13. 7 MPa and 28 MPa for V-nails without and with adhesive, respectively. Tt was concluded that 4 V-nails with 10 mm height in MDF joint-members would be recommended for joints without resin. In case of joints with resin, MDF joint-members with 3 V-nails of 10 mm would provide the highest stress-carrying capacity for craftsmen and producers of furniture and cabinets.

With respect to the importance of the wood and paper industry in Iranian economy and the interaction and linkages between the wood and paper sector with other economic sectors the status of this industry was investigated using Input-Output table for 1380 and hypothetical extraction method. Sensitivity of dispersion index as well as the wood and paper industry power of dispersion index were calculated as 451. 2 and 378. 1 respectively which suggests that this industry ranked first in sensitivity of dispersion and third power of dispersion among sections. This means that the wood and paper industry, possess identical and balanced status l among all sections with different categories in this respect. In the case of the hypothetical extraction method from the perspective of the production output is reduced by the amount of million 112345678 (Leontief pattern) and 132456789 cents (gosh pattern). In terms of stretching, the production ranking was calculated as 19 of 34.

In this study, the effects of mat moisture content and press temperature on physical and mechanical properties of three-layered oriented strand boards were evaluated. Two levels of mat moisture content (7% and 10%) and three levels of press temperature (180˚ C, 200˚ and 220 ˚ C) were applied and 12 mm thick laboratory boards were made from mixture of three clones of ten-years-old hybrid poplar (populus euramericana vernirubensis, p. e. I-214, P. e. 561/41) woods. The strands on the surface layers were aligned in the long direction of the board and the middle layer strands are cross aligned to the surface layers. In all treatments, board targeted density of 0. 7 g/cm3 and press time of 8 minutes and phenol-formaldehyde resin (PF) content of 7% based on the oven dry weight of the strands were kept constant. The mechanical and physical properties of the boards were measured as defined in relevant European standards test methods EN 300. Overall results showed that all boards made from above mentioned conditions exceed the EN 300 standard values for MOR, MOE, IB and TS24. The bending properties (MOR and MOE) of boards were significantly improved as the mat moisture content increased from 7 to 10%. The highest MOR was achieved at 10% mat moisture content and 220 ˚ C press temperature and the highest MOE was achieved at 10% mat moisture content and 180 ˚ C press temperature. The Modulus of Rupture (MOR) and thickness swelling (TS24) were significantly improved as the press temperature increased from 180˚ C to 220 ˚ C. The lowest TS24 was achieved at 7% mat moisture content and 220 ˚ C press temperature and the highest IB was achieved at 7% mat moisture content and 200 ˚ C press temperature.

The purpose of this study is evaluation of Tapioca and Corn cationic starch effects on the mechanical characteristics of paper from old corrugated containers. The recycling decrease waste paper properties and negative affect on the paper quality. The different treatments can improve the fiber quality. Cationic starch is effect treatment for quality improvement of recycled fibers. In this study, the cationic starch of Tapioca and Corn, each at three different levels 0. 5, 1 and 1. 5 % and comparison with samples (without cationic stretch). Hand sheets with a grammage of 120 g/m2 were made and their strength properties were measured. As well as, the absorption rates of two kinds of starch on the pulp were calculated using the Acid-Phenol method. The results indicated that the use of 1. 5% of Tapioca starch and 1% Corn starch had an optimum effect in increasing the strength of the produced paper. In comparison of kinds two of starch, Tapioca starch had more effective than corn starch.

In the present study, creep rupture behavior of a bagasse fiber-polypropylene composite was investigated. Two accumulated damage model (EDRM and Wood) and an energy based failure model (R-W) were adopted to describe the load duration influence on the studied composite. Results have shown that at very high stress levels, the EDRM and Wood models underestimated and overestimated the time to failure than static value respectively. This was attributed to the difference between application of static loading and creep loading. Findings indicated that the all three models were able to describe the creep rupture behavior of the studied composite and among this; the Wood model has shown a better fitting with experimental data, statistically. Based on findings in the present research, it can be concluded that the R-W model was more conservative in predicting time to failure in comparison with the two other models, and the reason can be attributed to the difference between failure criteria in energy based models and accumulated damage models. Results also showed that with increasing stress levels, the secondary stage of creep will shorten and at high stress level, the tertiary stage of creep will be more dominant.

The effects of nano-wollastonite on physical and mechanical properties of wood plastic composites made with dried sunflower stalks and alder wood flour were studied. Five levels of sunflower stalk flour (0, 25, 50, 75 and 100 percent based on oven dry weight of the wood powder) and nano-wollastonite powder in three levels 0, 3, and 5% were considered in the study. Physical and mechanical properties, including screw withdrawal perpendicular to surface strength, bending strength, modulus of elasticity, water absorption and thickness swelling after 2 and 24 soaking hours in water were measured in accordance with the standard DIN-EN. In order to examine the dispersion of wood and polymer as well as distribution patterns of nanoparticles in the polymer matrix SEM micrographs were taken. The results showed that by increasing of sunflower stalk flour in the mixture with wood flour up to 25% increased resistance to screw withdrawal and up to 50 percent increase in flexural strength and modulus of elasticity of wood-plastic composites, respectively. Sunflower stalk flour mixed with alder wood flour increased water absorption and thickness swelling after 2 and 24 hours immersion in water. The use of nano-wollastonite up 5% of the total mass of the boards improved the physical and mechanical properties of wood-polymer composite.

In this study the green algae (cladophora) nanocellulose was prepared and used to improve the CMP pulp strength. For the preparation of pure cellulose, algae samples were first treated with soda process and then bleached. Next, the produced cellulose was converted to Nanocellulose using ultrasonic method. Nano-cellulose from cladophora algae was mixed with CMP pulp in the ratios of 2, 5 and 8 percent. Finally, handsheets were made and the strength properties of handsheets were measured and compared with the pure CMP pulp. The results revealed sheets comtaining 8% nano cellulose had the highest density, tensile strength, burst strength, and the control samples showed the lowest values. Furthermore, the highest tear strength was related to control group; while, the samples containing 8% nano cellulose demonstrated lowest tear strength.