IRANIAN JOURNAL OF WOOD AND PAPER INDUSTRIES
Year:2021 | Volume:11 | Issue:4|Papers Count:14

Wood and wood products are used as a productive input as well as the final consumer goods of households. Part of this need comes from imports. Imports depend mostly on exchange rate developments, and importers respond differently to negative and positive currency shocks depending on currency conditions. Given the importance of this issue, the present study examines the asymmetric effects of foreign exchange shocks on wood imports and wood products in Iran, with an emphasis on the environment of foreign exchange shocks. In this regard, the EGARCH approach over the period 1974-2017 was used to model the formation of shocks and the data panel regression approach over the period 1993-2017 was used to investigate the asymmetric effects of shocks on wood imports and its products. The results show that the effect of negative and positive shocks on the amount of wood imports and its products is asymmetric. Trade openness reflects the ease of trade between Iran and its trading partners. The turbulent environment has reduced the impact of positive currency shock and increased negative impact of currency shock on the amount of raw wood imports, types of paper, and paper as final goods. The positive currency shock of the turbulent formation environment strengthens the effects of the exchange rate transition on the amount of finished goods and paper pulp. Positive and negative shocks have an asymmetric effect on the exchange rate environment. The effect of positive shocks is greater than negative shocks.

By developing attention to environmental issues and to the increasing attention of human society to health issues the use of environmentally friendly antibacterial compounds such as plant extracts for the production of antibacterial paper is very interesting. On the other hand, due to the high volatility of these environmentally friendly compounds, it is expected that encapsulating them in materials such as chitosan can increase their stability and control of release into the paper structure. Therefore, in this study, ethanolic extract of pomegranate peel in chitosan was encapsulated by ion gelation method and applied to the surface of the paper by spray method. The structural properties of pomegranate peel extract such as total phenol, total flavonoid and their antioxidant activity were investigated. Structural, barrier such as antibacterial activity and resistance properties of the prepared paper were also investigated. The results showed that nanocapsules of about 160 nm were obtained by ion gelation method, which were able to increase the antibacterial activity of the modified paper by about 35 mm against Staphylococcus aureus. In addition, the antibacterial activity of nanocapsule-modified paper was about two weeks higher than that of pure extract-modified paper. On the other hand, the presence of chitosan in the structure of nanocapsules also led to improved physical and resistance properties of the modified paper.

Nowadays, Polyethylene terephthalate (PET) yarn are replaced by cotton yarn because they are cheaper than cotton yarn. However, some cellulose properties such as high Glass transition temperature (TG) and moisture absorption are among important features of cellulose that plastic yarn lacks. Molding and blending are usual techniques but decline mechanical properties. Therefore, in this research, the surface of artificial polymer was grafted with viscose and coated with cellulose. For PET coating in the first method, the surface of polymer was hydrolyzed by dipping in the H2SO4 85% solution, and then the product was grafted with cellulose by dipping in the viscose cellulose solution. In this method viscose cellulose was prepared with Ethylene diamine, and Cu (OH) 2. In the second method, PET was first placed in a solution of H2SO4 85%, then was placed in a viscose cellulose solution that had been prepared by NaOH 50% and CS2. In the third method, the surface of polymer was hydrolyzed by NaOH solution and coated surface of polyester with paste of cellulose that included Ethylene glycol and urea. (FT-IR) were used to study properties of PET-graft-Cellulose fibers. The result of FT-IR exhibits coupling between PET and cellulose was accomplished and the first method is a better adhesive.

As the consumption of OCC pulp is increasing globally, practical studies are needed to reduce energy consumption and improve the quality of this pulp using enzymatic treatments. In this study, the effect of refining on cellulase enzyme performance on OCC pulp properties was investigated. OCC pulp with 4% consistency, 50 ° C constant temperature, 1 hour duration and 4-5. 5: pH with cellulase enzyme at three levels of 0. 1, 0. 3, 0. 5 percentages (based on dry weight of pulp) were pretreated. Pulp freeness and hand sheet strength properties were measured according to TAPPI standard codes. The results showed that the enzymatic treatment of cellulase increased pulp freeness and improved paper strength properties and this effect was more in unrefined OCC pulps than refined OCC pulps. Overall, enzymatic cellulase treatment can reduce pulp refining and reduce energy consumption and improve OCC pulp quality.

In this study, the effects of drought, fertilization, wounding and bending treatments were investigated on the content and composition of wood lignin in two-year-old eucalyptus seedlings (Eucalyptus camaldulensis). Results showed that drought-induced xylem had the highest concentration of lignin and guaiacyl (G) units and the lowest amount of hydroxyphenyl (H) and syringyl (S) units as well as the lowest S/G ratio compared with other treatments. In contrast, the lowest concentration of lignin and G units and the highest amount of S units and the highest S/G ratio were observed in fertilization treatment. Due to this treatment, H units increased. After wounding, lignin concentration did not change significantly compared with the control treatment and only slightly decreased. However, as a result of this treatment, G units increased significantly and H and S units and S/G ratio decreased. The most important chemical change observed in bending treatment was a sharp increase in H units and a decrease in guaiacyl and syringyl and an increase in the S/G ratio. Overall, it can be concluded that the chemistry of xylem is altered to give the plant the best ability to withstand environmental stresses. Guaiacyl lignin has a more protective role, and increased H lignin is associated with increased growth rate or increased stem flexibility.

In this study, the properties of non-copper and non-asbestos friction materials were investigated using cellulose waste to make brake pads. Friction materials including 20% cellulose waste (rice husk and paper waste) were used to make industrial brake linings and the shear strength, wear rate and friction coefficient of the linings according to the relevant standards were tested. The results showed that the average of shear strength of brake pads made of rice husk in normal condition was 35% and after heating was 24% higher than the brake linings made of paper waste. Also, the average of friction coefficient of linings made of rice husk in the thermal stages of wear and friction test was 35% higher than that of the brake linings made of paper waste and the wear rate of linings made of rice paddy was 67% less than linings made of paper waste. Also, all the properties of brake linings made of rice husk met the standard requirements. Thus, it can be said that by utilization of rice husk without copper and asbestos, the desirable properties of the brake pads can be achieved, and this formulation can be used in the production of automobile brake linings.

The use of wood in outdoor applications causes problems such as dimensional change, weathering and biological degradation. In this study, poplar wood was modified by three types of amino resins (melamine, melamine-urea and urea formaldehyde resins) and nano Zinc oxide (0, 0. 5 wt%). Then, the physical properties and weathering resistance of modified wood after six months natural weathering were measured. The results showed that the treatment of wood with amino resins reduced water absorption and improved dimensional stability of samples in which melamine formaldehyde resin had the best performance. Moreover, the addition of nano zinc oxide to the amino resins enhanced their performance in improving dimensional stability of samples. The results of the colorimetry and microscopic images indicate that the treating by melamine formaldehyde reduced the color changes and surface morphology of the samples, although the use of nano zinc oxide did not have a positive effect in this regard.

The importance of market concentration for government decisions and policies to regulate the market is inevitable. In this study, market indexes were calculated to identify the market status of particleboard imports and to help industry practitioners to identify the particleboard market and identify production potential. In this study, the market structure was measured using concentration ratios, Herfindahl-Hirschman, Hall Tideman, Comprehensive Industrial Concentration, and Hannah-Kay. The market structure was measured for the period 2010-2019. According to the calculations, the average concentration ratio of the four major exporting countries to Iran for the ten-year period studied was 97. 81% of the total import of particle board to the country. They indicates a market with a multilateral monopoly. Other indicators include the Herfindahl-Hirschman index at 5, 561, the Hall Tideman index at 0. 54, the Comprehensive Industrial Concentration Index at 0. 79, and the Hall Tideman Index at α value of 0. 6 to 3. 12, α value was equal to 1. 5, to 2. 27 and α value was equal to 2. 5 to 2. 02. The results have shown that the market situation on the import of paticle board was the multilateral monopoly. The status of this monopoly has fluctuated and changed over the past ten years due to the political and economic decisions of governments and the change in domestic production of particleboard. In this market situation, exporting countries can argue over price and export rates. Turkey, United Arab Emirates, Thailand, Italy and Russia has been Iran's most important trading partner in the particleboard import market during the period under review, with the most imports being indexed to these countries, indicating a multilateral monopoly.

The wet layer tensile strengths of the paper during production affects the frequency of breaking and its runability in the papermachine. In this study, the possibility of using cellulose nanofibers (NFC) and polyamide epichlorohydrin (PAE) vs imported long fiber kraft pulp (LF) was investigated to improve the wet and dry layer strengths of handsheet papers made from chemi-mechanical pulp (CMP). Strength properties of never-dried wet layer of papers with 35% consistency and air-dried papers were evaluated by pulp suspention and addition of 0 and 20% mineral calcium carbonate, NFC (at 2 levels, 2% and 3%), PAE (at 3 levels, 0. 5%, 0. 7% and 1%) and 20% of LF. Also, the effect of thermal treatments on the wet layer strength of papers containing 3% NFC and 0. 7% PAE at 100 and 130 ° C tempratures was evaluated. Results showed that the addition of NFC together with PAE improves the wet and dry layer strength properties of papers. In the case of wet layers of papers with 35% consistency, the addition of 3% NFC together with 1% PAE increased the tensile absorption energy (TEA) to 85%, although this was not as effective as using 20% LF (117%). In the case of air-dried papers, addition of 3% NFC and 1% PAE improved the papers TEA and tensile strength by 35% and 18%, respectively compairing with the addition of 20% LF. As a result of thermal treatments at 100 and 130 ° C, the tensile strength of dried papers increased to 22 and 22. 5%, respectively compared with the non-thermal treated papers. Overall, due to the positive performance of using NFC and PAE with thermal treatments, the combined use of 3% NFC and 1% PAE in CMP can be replaced by 15% LF to improve wet and dry papers strengths.

Wood modification with epoxy compounds, such as glycidyl methacrylate, could result in less moisture absorption and dimensional changes due to reduction in the number of hydroxyl groups and cell wall bulking. It is likely that change in the conditions of modification reaction would have a favorable effect on the physical properties by increasing the hydroxyl group’ s substitution. To determine the optimal modification condition with glycidyl methacrylate, samples were modified at different concentrations (10, 20 and 30%), temperatures (90, 120 and 150° C) and times (8, 16 and 24 hours). Based on spectrum analysis, decrease of hydroxyl groups intensity and increase of carbonyl groups intensity confirmed cell wall modification with glycidyl methacrylate. Cell wall bulking and hydrophobing due to modification led to a reduction in porosity and free water adsorption. According to the results of soaking-drying cyclic test, increase of glycidyl methacrylate concentration led to the reaction with more number of hydroxyl groups, and higher temperature and longer duration of modification reaction also led to an increase in the reactivity of the epoxy groups with the wood cell wall. The higher temperature of reaction led to maintenance of weight gain due to modification, via formation of a more stable structure against hydrolysis. Scanning electron microscopic images confirmed cell wall swelling and polymerization of glycidyl methacrylate in wood cavities. In a general conclusion, it can be claimed that the concentration of 20%, the temperature of 150° C and the time of 16 hours are the optimal conditions for modification with glycidyl methacrylate.

Surface modification with natural modifiers containing chemical bonding agents including rosin maleic can improve the physical properties of wood by reducing the number of hydroxyl groups. It is likely that an increase of temperature or the presence of a catalyst will have a more desirable effect on the physical properties of the wood by improving the hydroxyl group’ s substitution of the wood cell wall. This study was conducted to investigate the effect of different temperature levels and the presence of aluminum chloride catalyst for applying surface modification with Rosin Maleic, and evaluating the efficiency of the modification on the physical properties of Spruce wood. The samples were immersed in a rosin maleic solution with a concentration of 40% by weight/ volume (in toluene/xylene solvent) for 24 hours, and were heated for determine the effect of temperature, catalyst and leaching, under two temperature levels of 60° C, with and without catalyst, and 140° C, for 4 hours. According to the results, modification by reducing the hydroxyl groups (based on the infrared spectrums), improved hydrophobicity and dimensional stability of the treated samples. At the end of water immersion period, the higher temperature of reaction with formation a more stable structure against hydrolysis, led to maintenance the weight percent gain of modification. Increasing the modification reaction temperature from 60° C to 140° C create a significant difference in the measured properties, but the presence of the catalyst in the modification at 60° C reduced this difference and formed more stable structures. In a general conclusion, it can be claimed that the use of aluminum chloride as a catalyst in modification with rosin maleic, makes possible applying surface modification at ambient temperature, by forming a more stable structure against hydrolysis.

In this study, the effect of blending butyl acrylate with orthophthalic unsaturated polyester resin were investigated on toughness of the matrix and some mechanical properties of the composites with the same matrix. In the first phase, the blends, as matrix, have been fabricated by two different curing systems (cold cure with methyl ethyl ketone peroxide as catalyst, and hot cure with di-benzoyl peroxide as catalyst), each by combinations of 0, 5, 10, 15, 20 and 25 % monomeric butyl acrylate. Izod impact test was used to evaluate the toughness of blended matrix and pure matrix. In the second phase, kenaf and glass fiber-based composites were made by the blended matrix with the highest impact strength, then subjected to some mechanical tests such as toughness, failure energy, ultimate strength, modulus of elasticity, and heat deflection temperature. Test results showed that the highest value for impact strength, as 1. 91 kJ m-2 was attained for cold curing system with 15% monomeric butyl acrylate. Impact strength or toughness of blended matrix/fiber composites was around 31% more than that of for pure polyester/fiber composites. In addition, modulus of elasticity of blended matrix reinforced by fibers was around 133% less than that of for pure polyester/fiber composites. Finally, the results showed that monomeric butyl acrylate had a negative effect on ultimate strength and heat deflection temperature of blended matrix/kenaf and glass fiber-based composites

The purpose of this study was to evaluate the effect of cellulose nanofibers and its use as a strength enhancer to restore tensile strength and durability to historical paper relics. This research was conducted by analytical comparisons method and samples were collected by experiments related to research topics such as pH measurement, calorimetric and the measurement of tensile strength of the samples. In this study, treatment of cellulose nanofibers with weight percentages of 0. 5, 1 and 2%, was prepared as a suspension with water and used to consolidation of the paper samples. The treatment was sprayed three times by 3. 5 ml using spray can, then the treatment samples were thermally aged for 144 h at D776-92 ASTM, at a temperature of 105 ° C. Next, changes of pH, color and tensile strength of the specimens were investigated. Results showed that the pH of the samples after treatment ranged from 6. 98 to 7. 17 and after the aging, pH of the samples was in the near alkaline range of 6. 85 to 7. 11. The tensile strength index of the samples also increased in all 3 concentrations after treatment, however after aging, the tensile strength index of the samples decreased compared with the previous phase. The highest tensile strength after treatment was observed in samples with 2% treatment at 28. 2 and after aging 26. 3 Nm/g per meter.