Iranian Journal of Wood and Paper Science Research
Year:2020 | Volume:34 | Issue:4 (69)|Papers Count:10

The aim of current research was to investigate the effect of poplar fiber chemical treatment on physical and mechanical properties of wood plastic composite. Samples were made from acetylated poplar fibers with different weight percent gains (WPGs of 0, 14. 7 and 19. 5%), two levels of fiber in the composite (30 and 40%) and two levels of MAPP (0 and 3%). The samples were physically and mechanically tested. Then, the results were analyzed based on a complete randomized design (CRD) under a factorial experiment. Results revealed that the acetylation reduces the water absorption and thickness swelling and also improved some mechanical properties. Moreover, the results showed that the utilization of MAPP increases physical and mechanical properties of wood plastic composite. The results indicated that increasing fiber dosage from 30 to 40%, enhances water absorption, thickness swelling, tensile strength, tensile modulus as well as bending modulus, but reduces the 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 at 0. 68 using ICP-OES analysis. It was found that, 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 was 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 exothermic peak in DSC thermograms showed that the films degraded at higher than 200° C. 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. On the 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 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 stronger antibacterial activity against E. coli compared to S. aureus.

This investigation was concentrated to discover the possibility of utilizing corn cops residues in the production of particleboard. Two press temperatures of 170 and 180 o C, 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 was based on duncan multiple range test. The results indicated that the influence of the press temperature on modulus of rupture and modulus of elasticity was statistically significant and boards produced applying 170 o C reached the higher values. As the corn cop/poplar particles ratio 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 produced applying higher press temperature exhibited higher rate of thickness swelling. Lower ratios of the corn cop/poplar particle in the mixture of particles in the core layer improved the properties of the boards and two ratios of 50/50/ and 25/75 produced lower thickness swelling. The results of this research revealed that even though boards produced using corn cop/poplar particles did not produce comparable properties to the boards based on poplar particles, but it can be concluded that if 50/50 ratio of corn cop/poplar particles, press temperature of 170 o C 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) to introduce more charged groups on the surfaces of fibers which may lead to improved 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 severe 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 in conventional treatment. The results indicated that tensile 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.

Nowadays, development are speeding fast and new technologies are evolving which necessitate the today's wood products manufacturers to look for new developments and innovative services to enable themselves to ensure their survival in such tough environment. The entrepreneurial activity of wood furniture has always been an issue in this subject. It identifies new opportunities and transforms the industry's risky values and expose the nature of the wooden furniture industry to public sector. The present study has attempted to identify and rank the factors affecting the entrepreneurial intention of wood furniture products, considering the fact that the future economic security of the wood industry relies largely on the quality of entrepreneurs. In this research, descriptive-analytical method was used. The research community were among experts, manufacturers, entrepreneurs in the wood furniture industry, who assisted the researcher by answering the questionnaire. The data were analyzed, weighted and ranked using multi-criteria decision making algorithm (entropy and TOPSIS). The results showed that in human, economic, law and regulation factors index, structure and vitality of furniture and technical industry, sub-indices of individual entrepreneurship capacity, skilled labor force, control of production prices of furniture products, real aftermarket product warranty and design and Ideation ranked first in the research order.

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 (LBL) and composite methods. For this purpose, 80 gsm long fiber handsheet paper prepared at Mazandaran wood and paper factory was used. For the preparation of coating material, 1% polylactic 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 polylactic 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 polylactic acid on a magnetic stirrer and then was applied on a base paper. Finally, all papers were tested to determine the barrier properties including contact angle measurement, water absorption (Cobb) and water vapor transmission rate (WVTR) and also strength tests including burst strength 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 prevention in the paper and increases the degree of prevention at higher number of coating layers. However, it worth noting 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 and because of the connection with other sectors, this one has proven to play a significant role in production and productivity On the other hand, monetary policy is also stimulating the demand side of the economy for growth of production and employment and the level of prices. . 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 period 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, alone and with the addition of nano silica. However, in freeness test at acidic pH, the addition of chitosan combined with nanosilica reduced the drainage, and no significant effect was observed at neutral and acidic pH 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 studied to determine the configuration and the thickness of the adsorbed chitosan layer. This technique showed higher thickness layer of the polymeric adsorbed at alkaline pH, and thus, the possibility of the longer tail and loops configurations in the environment and more effective interactions beyond the electrical double layer.

Flammability is one of the most important parameters that limits the 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 paulownia wood modification with citric acid and its comparison with borax and ammonium chloride on the flammability. Test specimens were prepared and treated with solutions at 10% concentration in impregnation cylinder and empty cell procedure. Based on proposed treatment conditions, the treatment was performed by heating in oven at different temperature and times. The fire retardancy 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 other fire retardant materials, lower mass reduction, higher 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 the thickness of 8 mm and cores were 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, and with increasing the thickness of the core, bending stiffness and modulus of elasticity decrease, but impact strength increases. The highest values were measured from specimens made with a 30mm thick core, medium density fiberboard and Type A layout.