مجله تحقیقات علوم چوب و کاغذ ایران
سال سی و چهارم شماره 4 (پیاپی 69، زمستان 1398)

The aim of current research was to investigate effect of chemical treatment of poplar fibers on physical and mechanical properties of wood plastic composite. The samples were made from acetylated poplar fibers with different weight percent gains (WPGs of 0, 14.7 and 19.5%), two levels of fiber consumption (30 and 40%) as well as two levels of MAPP (0 and 3%). The samples were physically and mechanically tested. Afterward, the results were analyzed based on a complete randomized design (CRD) under a factorial experiment. Results revealed that the acetylation causes reduction of water absorption and thickness swelling and also improvement of some mechanical properties. Moreover, the results showed that the utilization of MAPP increases physical and mechanical properties of wood plastic composite. The research results showed that increasing of fiber consumption from 30 to 40% enhances water absorption, thickness swelling, tensile strength, tensile modulus as well as bending modulus, and also causes reduction of bending strength and impact resistance.

Bio-refinery includes technologies which can convert biomass resources to valuable products. In this study, carboxymethylation of the xylan-rich hemicelluloses extracted from sugarcane bagasse pith was performed. DS of the carboxymethyl xylan (CMX) was determined 0.68 using ICP-OES analysis. The presence of absorption bands at 1580 and 1311 cm-1 in the FTIR spectrum of the modified xylan are associated to the stretching vibration of C-O bonds of carboxymethyl groups. The carboxymethyl xylan/chitosan (CMX/CS) films were then prepared by casting method. XRD pattern showed that the intensity of the characteristic peaks of the chitosan reduced after film preparation which may be due to decreasing the crystalline nature of the film. SEM images showed that the surface of the film is uniform. The observed exothermic peak in DSC thermograms showed that the films degraded at higher than 200oC. Water vapor permeability (WVP) of the carboxymethyl xylan/chitosan film was measured 0.84± 0.1 g mm/m2 h kPa. Colorimetric analysis proved that the white index (WI) of the CMX/CS film increased as compared with xylan/chitosan film. In contrary, the yellow index (YI) of the CMX/CS film decreased. Swelling ratios of the CMX/CS and xylan/CS films were measured as 130.42 and 95.71 respectively. The prepared CMX/CS films exhibited higher tensile strength in compared to xylan/chitosan film. This may be resulted from the interactions between amine groups of chitosan and carboxyl groups of CMX. CMX/CS film exhibited the higher antibacterial activity against E. coli that S. aureus.

The aim of this investigation was concentrated on the possibilty of untilizing corn cops residues in the production of particleboard. Two press temperatures of 170 and 180 oC, and four ratios of corn cop/poplar wood particles (100/0, 75/25, 50/50 and 25/75) in the corn layer of the boards and 100% poplar wood particles in the surface layer were used. A combination of 16 treatments were reached and three laboratory boards for each treatment were made. Physical and mechanical properties of the boards were measured and statistically analyzed. The grouping of the averages were based on duncan multiple range test. The results indicated that the influence of the press temperature on both modulus of rupture and modulus of elasticity was statistically significante and boards produced applying 170 oC reached higher values. As the ratio of the corn cop particles in the particle mixture in core layer increased, both modulus of rupture and internal bonding deteriorated and the highest value were measured at 50/50 ratio of the particle in the core layer. The Boards which produced applying higher press temperature exhibited hgiher rate of thickness swelling . Lower ratios of the corn cop particle in the mixture of particles in the core layer improved the properties of the boards. So that the ratio of 50/50/ and 25/75 produced lower thickness swelling. The results of this research revealed that eventhough boards produced using corn cop particles did not produce comparable properties to the boards based on poplar particles, but it can be concluded that if 50/50 ratio of particles, press temperature of 170 oC is used for board making, the mechanical properties of the produced boards will meet the requirement of DIN specifications.

In this research, deinked pulp (DIP) was modified with carboxymethyl cellulose (CMC) in order to introduce more charged groups on the surfaces of fibers which leads to improve strength properties. Modification of the pulp was conducted at mild reaction temperature conditions of 85, 95°C and 120°C at 60 and 90 minutes, and under sever conditions of 120°C for 120 minutes in the presence of calcium chloride as electrolyte. The drainage time, water retention value (WRV), tensile strength, burst strength, brightness and opacity of CMC-modified pulps were measured and compared with corresponding values of blank (untreated) pulp and CMC-treated pulps as conventional treatment. The results indicated that tensile strength and burst strength of CMC-modified pulps were improved in comparison with unmodified pulps. The behavior of pulps was different in terms of optimum reaction condition. However, no significant changes were observed for optical properties of CMC-modified pulps. Water retention value of CMC-modified pulps decreased unexpectedly in some conditions.

Algorithm implementation )TOPSIS( Prioritize Factors Affecting the Entrepreneurial Intent of Wooden Furniture Products Abstract At present, the changes are so quick, that the producers of today's wooden products have to ensure their innovative survival, supply and services, which requires serious and practical attention to productive entrepreneurship. When entrepreneurship is accepted as a lifestyle by individuals in a community, that society is developing very rapidly.The work of the furniture business is always looking for change, and it responds to the opportunity to identify and values the viability of the industry,which is evolving and evolving the nature of the wood industry. The present research has tried to investigate the identification and ranking of factors affecting the entrepreneurial production of wooden furniture products, Because the future economic security of the wood industry relies heavily on the quality of entrepreneurship. In this research,descriptive-survey analytical method has been used Research community is the experts, manufacturers, and wood industry entrepreneurs who can help with research by answering questions from the questionnaire. Data were analyzed and ranked using multi-criteria decision-making algorithm (entropy and topsis). The research showed that in the human, economic, law and regulation index, the structure and vitality of the furniture and technical industry, under the indicators of individual entrepreneurial capacity, skilled labor, control over the prices of furniture products, the actual guarantee of the product after sale and design, and Ideas ranked first in the research. key words Wooden furniture products, Entrepreneurial intention, multi-criteria decision, entropy, topsis

The aim of this study was to investigate the effect of coating packing paper with polylactic acid-chitosan and polylactic acid-nano-chitosan complexes in two layer by layer and composite methods. For this purpose, was used of 80 grams long fiber handsheet paper Prepared from Mazandaran wood and paper factory. For the preparation of coating material, 1% poly lactic acid in chloroform and 1% chitosan and nano chitosan in acetic acid were prepared. In both methods, up to three layers of coating were finally applied and the final layer in each treatment was poly lactic acid. The paper samples were then dried in an oven at a temperature of about 100 ° C. In the composite method, each material (chitosan and nano-chitosan) was mixed independently with poly lactic acid on a magnetic stirrer and then seating on a base paper. Finally, all papers were performed for barrier tests including contact angle measurement, water absorption (Cobb) and water vapor transmission rate (WVTR) and resistance tests including burst resistance and air penetration resistance. Based on the results, the barrier properties of the coated Samples in both methods (layer by layer and composite) were increased compared to the control sample. Also, the results of the study of composite and layer by layer methods showed that the LBL method causes more prohibition in the paper and increases the amount of prohibition with increasing the number of coating layers. It is worth noting, however, that between the second and third layers of coating, changes were less pronounced. These changes were observed in both the LBL and composite methods. Air Resistance was also increased in the coated samples.

The industry sector is considered as one of the important and vital parts of the economy. On the other hand, monetary policy is also stimulating the demand side of the economy for growth of production and labor and the level of prices. In connection with other sectors, this one has proven to play a significant role in production and productivity. The purpose of this study was to investigate the effect of monetary policy on the value added in the wood products sector is based on the use of positive mathematical programming during the periode of 1990 - 2016. In the PMP method, the data of the existing conditions are reconstructed, the constraints of decision makers' truth and the manufacturer are considered in real terms, and this optimization model is very useful for analyzing policies in the present situation. The results of this paper showed that the decreasing and incremental policies of monetary variables (liquidity and bank interest rate) in different scenarios have an effect on the added value of optimizing that subsection. Also, an important indicator of this method is to calculate the optimal value added of each sub-section in its base year and its targeting capability in some other scenarios. For example, in the first scenario, in the case of a 5, 10, and 20 percent reduction in liquidity, value added will increase by 4, 8 and 18 percent in the wood and wood products industry. In this scenario, the drop in the policy variable will also increase the bank interest rate by as much as 5, 8 and 16 percent in the added value.

Chitosan is one of the biopolymers which possesses unique properties and has been recently considered in various applications such as paper-making. This polymer is soluble in acidic conditions and has the potential to act as a polyelectrolyte under the colloidal condition in the pulp. However, according to the studies, the capability of this polyelectrolyte was better in alkaline condition, in improving the drainage, retention and even strength properties of paper. Therefore, in this study, the performance of chitosan was studied in different conditions and the results were investigated based on the interpretation of the adsorption process and chitosan configuration using silicon wafer model and ellipsometry technique. For this purpose, bleached kraft softwood fibers were refined to a Canadian standard freeness of 300 ml and after addition of chitosan and nano-silica at different pH levels, freeness and fines retention parameters were evaluated. The results of this study confirmed that chitosan polyelectrolyte showed a good performance in increasing drainage and retention at alkaline pH, compared to the other pH levels, lonely and with the addition of nano silica. However in freenes test at acidic pH, the addition of chitosan along with nanosilica reduced the drainage, and no significant effect was observed at neutral and acidic pHs in the case of fine retentions. In order to interpret these observations and to ratiocinate the behavior of chitosan polyelectrolyte, the data obtained from the ellipsometry technique was investigated to determine the configuration and the thickness of the adsorbed chitosan layer which showed a higher thickness of the polymeric adsorbed layer at alkaline pH, and thus, the possibility of the longer tail and loops configurations in the environment and more effective interractions beyond the electrical double layer.

Flammability is one of the most important parameters that limits the range of wood use. Therefore, it is important to improve the fire retardancy properties of wood. The aim of this study was to evaluate the effect of modification with citric acid and its comparison with borax and ammonium chloride on the flammability of paulownia wood. Test specimens were prepared and in vitro cylinders were saturated with chemical solutions at 10% depletion. Based on pre-treatment conditions, the modification was performed by heating with oven at different temperature and time levels. The fire performance of the samples was evaluated by measuring different parameters. The effect of different fire retardants on water absorption and short-term swelling of the specimens was also studied. The fire test showed that by treating the samples with citric acid and fire retardant materials, less mass reduction, flame retardation time and longer ignition time were obtained. These findings were attributed to the formation of a protective carbon layer by citric acid and fire retardant materials. The flame retardant properties of borax treatment yielded better results than those using citric acid and ammonium chloride. In addition, water absorption and dimensional stability were improved by the presence of citric acid and fire retardant agents. The results of FTIR spectra showed that the carboxylic acid groups reacted with the hydroxyl groups of the wood and increased the weight of the samples. Changes in the crystallinity indices of cellulose, carbonyl and hydroxyl were also obtained from FTIR spectra.

The increasing demand for durable and lightweight raw materials in home and office furniture makes it necessary to investigate and optimize their properties. In this study, the effect of the sheet type, layout, and thickness were investigated on the mechanical properties of lightweight sandwich panels. Two types of sheets were used for making sandwich panels; medium density fiberboards and particle boards with a thickness of 8 mm and cores made of tube (bobbins) cardboard with heights of 30 and 50 mm, in three types of layouts. Urea formaldehyde glue was selected. The bending stiffness and modulus of elasticity were evaluated according to ASTM C 393 and impact strength according to DIN 5218 1992. The results showed that the thickness of the core had a significant effect on the mechanical properties, so that with increasing the thickness of the core, bending stiffness and modulus of elasticity decrease, but impact strength increases. The best results came from specimens made with a 30mm thick, medium density fiberboard core and a Type A layout.