مجله تحقیقات علوم چوب و کاغذ ایران
سال سی و یکم شماره 4 (پیاپی 57، زمستان 1395)

In recent years, there has been a lot of attention in producing and using of renewable and environmental friendly cellulose film and coverage. Regarding to the application of these films and coverages in different industries such as food, packaging and medical industries, their antimicrobial property is apparent. The purpose of this research is producing cellulose antibacterial film. At first, long fibr pulp convert to NFC using a supergrinder and then nanosilver treated films prepared applying silver nitrate through two different ways. In the first method, silver nanoparticles with considerations of 5 and 10 ppm reduced on NFC particles’ surface using retention aid. In second methods the prepared NFC film has been immersed in solution of Ag nanoparticle in concentration levels of 5 and 10 ppm. On higher concentration of used nanosilver solution, the amount of retained Ag nanoparticle in the first method was higher than the second one whereas, on lower concentration one, the differences of retained nanosilver values between two methods was a little. It has worth of mentioning that immerging method has the benefit of avoiding Ag nanoparticle wasting during pulp draining and nanosilver solutions could be reused simply.

The aim of this study has been utilization of recycled polyethylene in modification of physical and mechanical properties of particleboard. Therefore, three levels of resin consumption content ( 10, 7 and 4% ) and three levels of recycled polyethylene consumption content 5, 10 and 15% in surface layer of mat, particleboards produced. Also in order to influence of these variables on physical and mechanical properties of produced boards, 3 particleboards with 10% resin content in surface layer and without polyethylene as control samples produced. The physical and mechanical properties of boards measured and analyzed. The results of this study indicated that with increasing of the recycled polyethylene consumption content, the MOR, MOE and thickness swelling of boards improved significantly and the produced boards with 15% recycled polyethylene in compare with control boards increased 59 and 53% respectively. Also the results revealed that the water absorption of boards decreased with increasing of increasing of recycled polyethylene consumption content, and the minimum of water absorption of boards observed in the produced boards with 15% recycled polyethylene. Based on the results of this research and with increasing of polymeric residues in the envirement , we conclude that the utilization of recycled polyethylene in particleboard production has different advantages.

In this study, the possibility of using ash and orange bleached CMP pulp as replace in the full or part of CMP pulp of Mazandaran Wood and Paper Industries (MWPI) for making newsprint was investigated. For this purpose, first, ash and orange CMP pulps were prepared by using cooking conditions of MWPI with 101 gr/lit Na2O at the yield 85% in 75 minutes. Then some of the CMP pulps bleached with hydrogen peroxide, then its mixed samples with 15, 30, 45 and 60 percent to CMP pulp mill (control sample). From the mixed pulps provided hand sheets with 60 gr/m2 and these optical and mechanical properties measured and the data average were analyzed and compared. The results showed that newsprint from ash CMP pulp were more suitable than CMP pulp mill in all measured properties (except brightness) and orange CMP pulp (except opacity). Following bleaching with hydrogen peroxide, the brightness, tear, burst, tensile and breaking length strengths increased and opacity decreased. The results showed that ash and orange unbleached CMP pulps are not good properties for newsprint production and these pulps have to bleach with hydrogen peroxide. In generally, the best mixed pulps were includes 45-60 percent ash and orange bleached CMP pulps with 40-55 percent MWPI CMP pulp for newsprint production.

Nowadays, the leading experts of the world’s furniture industry approve the existence and potentials of Iran furniture industry and more importantly, they believe it can advance and grow much more in the future. So, the purpose of this paper is investigating of the domestic living furniture producer’s point of view on the way of manufacturing and selling of these products. In this regard, information from aware academic specialists was gathered. 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, designing and finally producer’s satisfaction of government and business suporters, respectedly had the most to least degree of importance for domestic living furniture producers to the way they manufacture and sell their furniture products.

The current research work was planned to investigate the possibility of zinc oxide nanoparticles synthesis using hydrothermal method in wood structure and 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 according toASTM-D143 and EN113 respectively were treated by vacuum- pressure method using cylinder experimental. The mechanical tests were considered for each level 5 repeat and for biological test for each level 10 repeat. The presence of zinc oxide nanoparticles on cell wall and styrene in the cell cavities were confirmed by Scanning electron microscopy. According to the results, bending strength, bending modulus, hardness and pressure parallel to grain for nano/styrene samples with highest improvement were increased 36.74, 40.23, 60.58 and 25.07 in comparison with control respectively. Also, decay resistance of treated samples increased, so that maximum and least weight loss were recorded for control and nano/styrene samples with 25.81 and 3.37% weight loss.

In this study, the mechanical and biological properties of modified poplar wood with glutaraldehyde and paraffin were investigated. Modification was performed with glutaraldehyde at different concentrations of glutaraldehyde, 5, 10 and 20% using magnesium chloride as a catalyst and then subsequently with paraffin by vacuum-pressure method. Increasing concentration of glutaraldehyde caused to weight gain and bulking wood cell wall, 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 standards EN113 and ASTM D143-94, respectively. Scanning electron microscopic images showed bulking of cell walls and paraffin presence in cell cavities. According to results of TGA, increasing of modification intensity decreased mass loss due to cross linking 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 present in the modified samples improved it. The Glutaraldehyde increased compression strength parallel to grain and hardness that the improvement was more obvious in combined modification. Modification with glutaraldehyde enhanced decay resistance exposed to white rot fungi, and this improvement intensified at the presence of paraffin. Inhibitory influence of chemical modification on wood attacking white rot fungi can be attributed to decreases the wood moisture, bulking of cell walls and blocking cell cavities.

The present research project was carried out to find out tension-carrying capacity of corner miter V-joints in tensile and compression directions to be compared with those of dovetail joints. Variables included the type of wood-composites 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 tension-carrying capacity under compression tension was significantly higher than those in the tensile tension. Moreover, MDF joints showed higher tension-carrying capacity in comparison to those made from particleboard. Joints with resin were significantly stronger than those without resin. Increase in the number of V-nails resulted in an improvement in the tension-carrying capacity in both directions. Based on the results of the present research project, it was concluded that V-nails are preferred to dovetail joints from different perspectives, including their lower production expenses, lack of need for an extra step to mill the joint so that joint bits be inserted into, fast and easy installation of V-joint in one-step process, as well as higher tension-carrying capacity. Based on the obtained results indicating the maximum tension-carrying capacity of 13.7 MPa and 28 MPa for V-nails without and with adhesive, respectively, it was concluded that 4 V-nails with 10 mm in 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 tension-carrying capacity for craftsmen and producers of furniture and cabinets.

Considering the importance of the wood and paper industry for the Iranian economy and interaction and linkages between the wood and paper sector with other economic sectors. In order to do so, Input-Output table for 1380 and hypothetical extraction method has been used. Calculation of sensitivity index of publication as well as the wood and paper industry publishing strength index respectively with figures 451.2 and 378.1 suggests that this industry ranked first and third release power sensitivity in between sections is And this means that the wood and paper industry, more than the average total other sections with the other categories in this connection and communication as well as alike and more balanced sections. In the case of the hypothetical extraction method from the perspective of the production output decreased the amount of million 112345678 (Leontief pattern) and 132456789 cents (gosh pattern). In terms of stretching the production ranking 19 of 34 of its assigned section.

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 ˚c and 220 ˚c were applied and 12 mm in nominal thickness laboratory boards were made from mixture of three clones of ten-year-old hybrid poplar ( populous euramericana vernirubensis, p. e. I-214, P. e. 561/41) while the strands on the surface layers are 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 min and phenol-formaldehyde resin (PF) content of 7% based on the oven dry weight of the strands were held constant. The mechanical and physical properties of the boards were measured as defined in relevant European standards EN 300 for OSB/1 and OSB/2. Overall results showed that all boards made from above mentioned conditions exceed the EN 300 standards 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 aim of this study is investigate the effect of Tapioca and Corn cationic starch on the mechanical characteristics of paper from old corrugated containers. The paper recycling decrease its properties and affected on the paper quality. For promoting these fibers may be effective the use of different treatments. Cationic starch is effective treatment for recycled fibers Promotion.
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 grammag 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. Concerning the comparison of these different types of starch, the tapioca starch was more effective than the 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 in ratio of the mass wood dry flour containing 0, 25, 50, 75 and 100 percent and nano-wollastonite Powder in three levels, 3, and 5% were considered as variables of the study. Physical and mechanical properties, perpendicular to the screw 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 intersection of wood and polymer as well as distribution patterns of nanoparticles in the polymer matrix microscopic photos were taken. The results showed that by increasing of sunflower stalk flour in the mixing 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% in relation to the total mass of all the boards improved the physical and mechanical properties of wood-polymer composite.

Nowdays, algae considering marine ecosystem are regarded as producers and the first continuum that receives solar energy. Hence, they ensure the needed energy for the aquatic organism living. In global herbal division, algae have 1800 genus and 21000 types. Because of their presence in air rather than underground water, algae allocate larger arena to themselves in comparise to other herbage. Based on accomplished studies, it is rated that algae have more than 7000 types in terms of biological diversity. Algae are used a lot. They are consumed in food industry, dung preparation, medicinal consumption and etc. In this study the green algae nanocellulose was used to improve CMP resistance.For the preparation of pure cellulose, algae samples initially affected the soda process and then were affected by bleaching sequence.. Next, the obtained cellulose has been converted to Nano-cellulose by using ultrasonic method. Nano-cellulose from cladophora algae was mixed with CMP in the ratios of 2, 5 and 8 percent. Finally, handmade paper was made and its resistive (strengh) properties were studied and compared with the pure hardwood CMP pulp. The results revealed that 8% treatment group had the highest density, tensile strength, burst strength, and control group had the lowest amount. Furthermore, the highest tear strength was related to control group; while, the lowest tear strength was for 8% treatment group.