IRANIAN JOURNAL OF WOOD AND PAPER INDUSTRIES
Year:2019 | Volume:10 | Issue:2 |Papers Count:13

The amount of specific heat capacity is important for processes that require heat transfer in wood, as well as for design of wood structures that undergo high temperature changes during day. In this research, specific heat capacity of thermally modified oak were measured in comparison with unmodified wood in the temperature range of-20 to 20 ° C under dry and wet conditions using differential scanning calorimetry (DSC). Results showed that there was no significant difference between the specific heat capacities of two types of wood at dry condition, and the average values were 1. 47 J. g-1K-1 at 20 ° C and 0. 84 J. g-1K-1 at-20 ° C. In contrast, the specific heat capacity of the modified wood at-20 ° C under wet condition was greater than that of unmodified wood, and more heat flux was used to melt the ice. In contrast to a linear relationship between the dry specific heat capacity and temperature in the range of 0 to 20 ° C, the relationship was nonlinear for temperatures below 0 ° C.

In this study, for synthesizing and producing of low sensitive nitrocellulose, acetylation method was used. At first it was necessary to produce nitrocellulose with various nitrogen contents (9/50, 11/50, 12/40 and 12/80%). By using effective parameters on the nitrogen content such as mixture acid percent, nitration time (35, 45, 55 and 60min), acid to cellulose ratio (60and 75) nitrocellulose was produced and then with constant parameters of acetylation reaction such acetic anhydride (240%), reaction time (3 hr), reaction temperature(40° c) and variable parameters such as using and not using using toluene, and catalyzer percent (perchloric acid 0/03 and 0/04%), cellulose nitrate-acetate was produced. The results showed that without using toluene, a gelatinous product is produced that isn't capable of drying. Also, with using of 0/03 percent catalyzer content, cellulose nitrate-acetate with white color fiber can be achieved. The IR spectroscopy of showed when nitrocellulose is converted to cellulose nitrate-acetate in acetylation reaction, hydroxyl group of nitrocellulose is replaced with acetyl group. Also, results showed when nitrocellulose is converted to cellulose nitrate – acetate, the peak of hydroxyl group decrease with increasing of nitrogen content. In the nitrocellulose with 12/80 nitrogen content the peak of hydroxyl were eliminated. The result also showed that by acetylation of nitrocellulose: solubility, thermal decomposition and stability of nitrocellulose were increased and burning rate and calories were decreased. Finally, it has been showed that by acetylation of nitrocellulose, the sensitivity was decreased and stability in expose temperature and storage condition was increased.

27 percentage of Gilan province (North of Iran) with approximately 150 thousand hectares is under cover of Shafaroud Forest Company which is utilized in form of 73 forestry plans. Regarding the ecological futures of the region, promising species and the Shafaroud's potential, three species i. e. poplar, alder and Loblolly-pine were investigated to determine optimal product and target markets. Finally they were categorized for future investments on forestry plans and sustainable forest management. For these purposes, after review of previous studies and some interviews with experts, effective factors on determining optimal product and target markets were divided into 6 main categories and 49 subcategories. Sorting of categories and subcategories was conducted by Analytical Hierarchy Process (AHP) and according to experts comments. The result showed that Loblolly-pine (0. 470), alder (0. 299) and poplar (0. 230) had more importance, respectively and accordingly they propose for wood farming and forestry plans in this order. Among main categories, pulp and paper, furniture, wood products, building, accessories and tools, and transportation were sorted according to their relative weight. In case of subcategories, tissue was the most important product and furniture (both office and home furniture) took place in next ranks.

In particle board plants different chippers and flakers are used to convert logs to wood particles. Different parameters affect the final result. This study aims to evaluate the effect of moisture content and species on quality of wood particles and energy consumption in knife ring flaker. Hence two different species including poplar and oak were used. Besides, two moisture contents of 12% and 30% were evaluated. First, logs were converted to lumbers; then they were kept in open air for 20 days. After that they were conveyed to drier chamber and dried to reach the aforementioned moisture content. Next, using drum chipper, the lumbers were converted to chips. After that, the resulting chips were fed to knife ring flaker following the experimental design. The energy consumption was measured using multi-channel precision power meter. For precise evaluation of energy consumption for each treatment, equal volumes of chips at constant time were converted to wood particles. Finally, the resulting wood particles were classified using laboratory shaker following EN 151491. The result showed that energy consumption during the producing wood particles using knife ring flaker for oak is higher than poplar mainly due to higher density of the former. In oak, increasing moisture content from 12 to 30 percent energy consumption decreased that was related to softening effect of water. However, regarding poplar, increasing moisture content increased energy consumption. At the same moisture content, oak gave wood particles with higher quality in comparison to poplar. Besides, in both species increasing moisture content resulted in higher quality wood particles.

According to climate conditions and destruction of forests, afforestation is necessary for soil and water conservations and supply the human requirements. Plantations with poplar species, in addition to wood production, have many environmental and social benefits. However, there is no market for them. In present study, two items of ecosystem services of a poplar plantation located in the Khorramabad city were considered in terms of the economic point of view and was evaluated with different approaches. In this study, the market direct valuation methods and alternative cost method were used to determine the value of wooden and non-wooden products, respectively. The results showed that the values of gas adjustments and wood production were estimated to be 1/41 billion rials and 1/54 million rials per year, respectively. Therefore, the gas adjustments function comprises the larger part of the total economic value of the evaluated functions. These results indicated that the value of environmental aspect of the studied plantations was higher than that of the wood production.

This research was conducted to compare the effect of tetraethoxy silane and triethoxy vinyl silane on chemical structure and physical properties of poplar wood. Test samples were divided into control, modified with silane compounds, vinyl silane / benzoyl peroxide initiator, and combined of silane/ benzoyl peroxide. Modifier resulted in change of chemical structure, increase of density and bulk of wood samples. Weight gain of triethoxy vinyl silane modified samples was higher than tetraethoxy silane modified ones, which was more significant in presence of initiator. The initiator significantly reduced water absorption and dimensional changes in modification with silane. At the end of soaking-drying test, weight loss and bulking coefficient of tetraethoxy silane modification was higher than triethoxy vinyl silane. The lowest loss of weight and bulk were calculated for triethoxy vinyl silane /benzoyl peroxide and combined modified samples. In the first cycle, water absorption of the triethoxy vinyl silane modified samples was more than tetraoxysilane, and from second cycle, this trend was reverse. Initiator with polymerization of triethoxy vinyl silane decreased water absorption and volume swelling, more significantly.

An important source of lignin is the spent pulping liquor, known as black liquor. Due to high volume produced of black liquor, its treatment is very important for economic and environmental reasons. Alkali lignin can be extracted from black liquor in pulping process to produce value-added chemicals, but its limited water solubility hampers its end-use applications. In this work, first, bagasse soda lignin was extracted form black liquor with lignoboost process and was modified with sodium sulfite under hree different treatment conditions (75° C, 6 h and 90 ° C, 6 h and 90 ° C, 4 h). The structure changes, and molecular weight, thermal behavior and elemental analysis of the product were, respectively, assessed by using FTIR, SEC, TGA and CHNS. The results showed the sulfonated lignins are different from unmodified lignin in the amount of sulfonate group and have more sulfonate groups. Also, the molecular weight, solubility and thermal behavior in sulfonated lignins were increased due to sulfonate group compared to the unmodified lignin.

The objective of this study was to investigate the effect of an experimental spray coating method of cellulose nanofibers (CNF)/nanochitosan suspensions on the barrier and strength properties of printing and writing paper. Spray coating operation was done using two levels of CNF (2 and 4 percent) and nanochitosan (0. 5 and 1 percent), under constant spray conditions including spray time (20 seconds) and spray distance (20 cm). Field emission scanning electron microscopy (FE-SEM) was done for the morphological assessments. Barrier and strength properties were determined according to the related TAPPI standard test methods. FE-SEM analyses showed that the mean diameter of CNF and nanochitosan were as 28± 10 nm and 40± 10 nm, respectively. Results also showed that spray coating method of CNF/nanochitosan significantly improved the barrier and strength properties. It can be totally concluded that spray coating, having advantages compared to the auto bar coating method (including uniform distribution of the coating suspension, lower equipment costs, lower use of the coating material), is an appropriate method for the improvement of barrier and strength properties of printing and writing paper. In addition, use of OCC for CNF preparation, can be considered as a positive step in development of the paper recycling application, environmental preservation and, production of a value-added product from linocellulosic wastes.

In the present research, the mechanical and physical properties of poly lactic acid-canola stem flour composites made by compression molding technique were studied according to ASTM standards. According to the results, it was found that modulus of rupture, tensile strength and impact strength were decreased by increasing the amount of canola stem flour in comparison with pure poly lactic acid (PLA) composites. In contrast, the elastic properties including Young's modulus, flexural modulus, and surface hardness increased. The addition of canola stem flour also increased water absorption and thickness swelling. Furthermore, a significant increase in the composite crystallinity degrees was observed in the study of thermal properties by DSC test. It can be concluded that the use of canola stem as a cheap and renewable lignocellulose source can improve some mechanical properties of the composites, as well as having a filler role in making composites.

The purpose of this study was to improve the properties of the coated papers by calendering. Two types of printing and writing paper (75 and 125gsm) and five coating suspensions (the first suspension with 22. 9% binders and 50% solids content, the second with 24. 73% binders and 50% solids, the third one with 22. 9% binders and 30% solids, fourth suspension with a 24. 73% binders and 30% solids and the fifth suspension with 42. 3% binders and 50% solids content) were used. The coatings were composed of 80% kaolin clay, 20% ground calcium carbonate, dispersant and different ratios of polyvinyl acetate and lactic acid. The base and coated papers were dried after coating. The calendering treatment was carried out at a temperature of 55° C and 60 kg/cm linear pressure. Air resistance, thickness, water absorption, tearing resistance and bursting strength of papers were determined. The calendering operation was effective in reducing the thickness and increasing the air resistance. Water absorption was decreased only in 75gsm samples. As a result of calendaring, the mechanical properties were improved slightly, but in most cases, this treatment had an adverse effect on the mechanical indexes.

This study aimed to fabricate the bilayer scaffold containing nanocellulose/poly (vinyl) alcohol (CNF/PVA) and evaluating its potential use as a mimic for skin tissue engineering. A continuous process of layer addition with two different concentrations of polymers by freeze-drying technique was used. FE-SEM analysis indicated that the obtained scaffolds had interconnected porosity and pore size, which increased in lower concentration of polymers. The scaffolds were also characterized by water uptake, mechanical properties and MTT assay. Lower concentration of polymers increased water uptake and decreased mechanical strength. The MTT assay results showed that these nanofibrous scaffolds meet the requirement as a material for tissue engineering.

The inherent heterogeneity features of lignin when increased during kraft pulp process, restricts the technical lignin utilization in value added applications. Organic solvent fractionation of lignin is notable as an efficient way to obtain lignin fractions with well-defined characteristics. In the present study, two industrial kraft lignin were separated to the soluble and insoluble fractions by single step extraction process using acetone as organic solvent. The parent kraft lignin and the soluble and insoluble fractions thereof, characterized by using various techniques including GPC, FT-IR, 31P NMR and DSC. The results showed different molecular weights, functional hydroxyl groups and also glass transition temperature (Tg) for the lignin fractions. The soluble fractions exhibited lower molecular weight and polydispersity, less aliphatic and more total phenolic hydroxyl groups and lower Tg than the soluble fractions. The results indicated that solvent assisted single step extraction can easily provide access to the industrial lignin fractions with different properties. Understanding correlations between physical-chemical properties of lignin fractions can be used as a tool for selection of tailored lignin fractions for the potential of value added applications.

Clear coatings, such as transparent acrylic paint have a relatively short life in outdoor exposure because solar radiation can readily penetrate through such coatings and reach the wood surfaces and cause degradation in cell walls of wood tissues. This phenomenon can be reduced by using suitable UV absorbers in the structure of coatings. Therefore, in this study, the transparent acrylic coatings were modified with nano cellulose (1 wt%) and nano zinc oxide (0 and 0. 5 wt%) and then applied on beech wood specimens by brush. Subsequently, these specimens were exposed to natural weathering for six months. The results of pull-off adhesion, contact angle, colorimeter, ATR-FTIR spectroscopy and microscopy images showed that the use of nano zinc oxide and nano cellulose increased weathering resistance of coated samples where the weathering degradations of these samples were minimum, compare to others.