مجله صنایع چوب و کاغذ ایران
سال نهم شماره 4 (زمستان 1397)

Occupational vibration is considered as one of the most important occupational problems in chainsaw work in a forestry environment. The aim of this study was to measure the hand-arm vibration of the chainsaw operator in the bucking operation of Persian ironwood, popular, and alder logs in the Kheyrud Educational and Research Forest. In this study, bucking operation of two trees of Persian ironwood, popular, and alder species with different wood density was measured in a transverse section. Vibration measurement was carried out using a SVANTEK vibration device at the same time in X, Y and Z directions. The averaged vibrational intensity indices (aeq), total ahv chainsaw vibration, vibration transmission coefficient (Tr and daily exposure period) (A8) was used to assess the vibration of the chainsaw. The results of this study showed that the mean averaged vibration ratio of the averaged jet propulsion (aeq) in all three axes ((X, Y, Z more) Is a species of poplar and alder, and in Persian ironwood species, there is a significant increase in direction X and direction Z is the least amount of vibration (P

In this study, the alkaline pre-extraction followed with soda and monoethanolamine pulping of barley straw was investigated. The pre-extraction stage with removal of 34percent hemicelluloses due to highest yield was selected as optimum treatment. The results of pulping show that pre-extraction stage resulted in decrease of yield in both pulping processes meanwhile only in soda process the kappa number was influenced with pre-extraction stage. Tensile and burst indices of pulps drop because of pre-extraction stage. Unlike of these indices, the tear index of soda pulp from pre-extracted barley straw has been increased. The brightness of soda pulp from pre-extracted barley straw is increased while the pre-extraction stage has no significant effect on brightness of monoethanolamine pulps. The opacity of pulps remains unchanged after pre-extraction.

This study was focused on the preparation of an environmentally friendly nanocellulose based hydrogel in the form of pads. Hydrogels are hydrophilic three dimensional network with crosslinks, swells in water but don’t dissolve. In this research nanofibrillated cellulose and Hydroxyethyl cellulose with different ratio (1:1, 2:1, 3:1) were used to make hydrogel. Also, citric acid which has a significant advantage over other crosslinking agents in terms of toxicity and price, has been used in different amounts of 10% and 20% by weight to crosslink. In order to find optimal hydrogel preparation conditions, FTIR analysis, FESEM, time dependent swelling measurement and evaluating the thermal and rheological properties were performed. Samples with a lower ratio of nanocellulose to hydroxyethyl cellulose were found to be inappropriate due to the loss of their apparent integrity in the swelling measurement. According to FTIR results, cross-linking were performed only in samples with the highest ratio of nanocellulose to hydroxyethyl cellulose in different amounts of citric acid. Therefore, the hydrogels' characteristics were mainly influenced by the ratio of nanocellulose to hydroxyethyl cellulose and the amount of citric acid had less effect on these properties. These two successful final samples showed acceptable properties in other evaluated properties and led to the selection of optimal reactive ratios for the preparation of hydrogels for use in various industries, including the pharmaceutical industry.

The purpose of this study was to measure the amount of quality decrease the Hornbeam (Carpinus betulus) wood after three period four months (12 months) of storage in the forest and compare it with the beginning of the period and identify the destroyer fungi that appeared. This research was carried out in Shastkolah in Gorgan. 15 Billets with 30 cm diameter class and length of 220 cm were cut from a Hornbeam tree and all were healthy and stored inside the forest under the same conditions and in contact with soil. The billets were cut at 50 cm intervals at each stage for physical and mechanical experiments were measured based on conventional methods and related standards. the white decay fungi Sterium hirsutum (Willd.),Trametes gibbosa Fr.,Trichaptum biformis Fr. identified on the billets. According to the results, with increasing storage time in the forest, all physical and mechanical properties, except water absorption, decreased. The maximum and minimum changes in physical properties were related to the percentage of water absorption and basic density respectively, also the maximum and minimum changes in mechanical properties related to impact resistance and modulus of elasticity respectively

this study seeks to examine the effect of targeted subsidies on the demand for raw and semi-processed wood (wood Russian, MDF Melamine, MDF Higlass, Chipboard, Litron and Door Cover) in khorramabad City during the period of 2009-2016. The data of the present study was compiled seasonally from spring 2009 to winter of 2016 by documentary and from the 7th wholesale sales offices of this city and analyzed usingthe almost ideal demand system (AIDS). The results showed that the purposefulness of subsidies had a structural failure due to the demand pattern of wood and wood products. In other words, the demand pattern of people before and after the targeting of subsidies is different, which means that the reaction of the applicants of each product to their prices, the price of other products and changes in income before and after the purpose of subsidies has changed.

The purpose of this study was to evaluate the biodegradability of composites made from bamboo flour and poly lactic acid using physical properties and biodurability examinations. On the other hand, the effect of the amount and size of the bamboo flour particles on the physical properties and durability of the biocomposites was another objective of the research. the bamboo flour and polymer were mixed up in a counter-rotating twin screw extruder. the biocomposites boards were produced by compression molding method. The samples were cut and evaluated according to the suggested specifications in the ASTM and EN-113 standards. The results showed that the thickness swelling and water absorption of the composites were increased significantly by increasing the amount and size of bamboo flour particles. Also, biodurability of the biocomposites samples against the studied three fungi species showed that Gloeophyllum trabeum sharply caused high mass losses in all samples by increasing the amount of bamboo flour, while pure polymer (PLA) had a very high durability against the fungi.

In this study, fracture toughness and internal bonding of OSB made from Poplar (Populus nigra) was studied. For this aim, ratio of UF to MF (20; 80, 40:60, 60:40 and 80:20), mat moisture (11 and 13), press time (5 and 7 min) and the panel thickness (12 and 16 mm) were chosen as variables. Specimens based on Taguchi design of experiments with the array of L8 (4^1 2^3) were produced and fracture toughness and internal bonding were determined following ASTM E399 and 319 EN respectively. Fracture toughness was determined using stress intensity factor and fracture energy. The result of percentage contribution and the variables ranking showed that the most determining factor on fracture toughness is the ratio of UF to MF. The effect of press time on stress intensity and internal bonding and the effect of panel thickness on fracture energy had the least importance. The highest fracture toughness was belong to OSBs made with UF to MF ratio of 60:40, mat moisture of 11%, press time of 7min and the panel thickness of 12 mm. The highest fracture energy and stress intensity factor was 2944 J/m2 and 0.19 MPa respectively. The optimum treatment was UF to MF ratio of 80:20, mat moisture of 13%, press time of 7min and the panel thickness of 12 mm in light of gaining the highest internal bonding (0.95 MPa).

In this study, the effect of spruce wood surface lamination by film coatings on the color changes and surface quality of substrate were investigated after accelerated weathering by using a colorimeter (CLE) and confocal laser scanning microscope (CLSM). For this purpose, the surface of spruce wood (Picea abies L.) was laminated by alkyd, water and solvent based polyurethane coating films using a special adhesive tape of aluminum and carbon fiber. The coated samples were put in the accelerated weathering (QUV) device for 45 days and then changes in the color and roughness due to weathering were analyzed. The results showed that, the coating films and wood surface discolored due to weathering and the minimum amount of discoloration was related to the solvent-based polyurethane (SP), waterborne polyurethane (PW) and solvent-based alkyd (SA), respectively. Also, the results of confocal laser scanning microscope showed that the roughness variations on the wood surface depend on the type of coating and the main factor in surface roughness changes depends on the absorption percentage and the resistance of the coating to ultraviolet radiation. The lowest and the highest roughness at the coating film and wood substrate were found for the samples laminated by the solvent-based polyurethane and solvent-based alkyd, respectively.

In recent years, plenty of studies have focused on the application of cellulose nanofiber to improve the mechanical and physical properties of paper. But, in this research, the effect of lignocellulose nanofibers produced from recycled old corrugated container as raw material using ultra-fine grinder, on some mechanical properties and production process parameters of paperboard was investigated. TEM images of produced nanofibers indicated that the nanofiber width was in the range of 10-80 nm. Then, various dosages of nanofiber were applied by bulk addition method to the furnish. Eventually, the evaluation of tensile strength revealed that the application of 5% lignocellulose nanofiber caused more than 50% increase in tensile strength of produced paperboard. Although, the bulk addition of high dosages of the nanofiber resulted in reduction of bending index (bending stiffness), tear index and especially freeness of the furnish.

In this study the effect of open time and hardener content on bending strength of finger jointed made of three wood species; Beech, Fir and Poplar was investigated. For this purpose wooden samples with dimension 25mm width, 35 mm thickness and 350 mm length from three species were prepared. After three weeks storage in climate room, in order to form finger joint pattern, samples were cut at the half of length. Then the finger joint pattern was done in new exposed cross sections of samples. After that the joints were bonded with three PVAc glue types; pure, with 10% and with 20 % hardener. The second variable of study was open time that was controlled in two levels of 2 and 4 minutes. The clos time and press time were constant which were adjusted on 2 and 30 minutes respectively. The joints were pressed in a special wooden frame by hand clamp. After making joints, they were stored in climate room for three weeks and then the three point bending test was carried out according to ISO 10983. The results showed that by adding isocyanate hardener up to 20% the bending strength increases significantly. The longer open time could not improve bending strength even it caused strength dropping in some treats but this changes were not significant. The strength of joints made with poplar wood was lower than beech and fir although this difference was not significant statistically. Finally the best condition for making this joint was determined by application of 2 min open time and using 10 % PU resin as hardener.

Fundamental studies in wood of trees and shrubs can reveal the possibility of their utilization in various applications or lead to create a database of different wood species. Wild service tree (Sorbus torminalis L.) is a rare and valuable tree species in Hyrcanian and Arasbaran forests. This study were investigated some anatomical, biometrical, physical and chemical properties of wild service wood. Wood samples were cut from Sangdeh forests of Mazandaran. Studies have shown that wild service tree is extremely compact and dense; its average density is 832 kg m-3 and its shrinkage is about 16%. Growth rings boundaries are indistinct. From anatomical view, it is a diffuse-porosity wood and its vessels are exclusively solitary, long (999 microns), narrow (55 microns) and are not visible with naked eye in transverse section. Growth ring boundaries can be distinguished by only two to three compact fiber layers. Rays parenchyma is heterogeneous, exclusively 2-seriate (partially uniseriate). The fibers are of vascular tracheids type with an average length and cell wall thickness of 1575 and 9.33 micron, respectively. The content of cellulose, lignin, extractives and ash were 49.8, 18.9, and 2.3 percent, respectively. Preservation of valuable tree species of the northern forests such as wild service tree should be on the agenda of natural resource custodians.

In this study, phenol was partially substituted with urea to reduce the production cost of phenol formaldehyde resin (PF), and a new resin phenol-urea-formaldehyde (PUF) was synthesized. Different formulations of resin PUF with different molar ratios were made using different methods. The structure of the formulated resins and their coagulation behavior were evaluated with infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC), respectively. FT-IR and DSC analysis indicated the best results for the synthesized PUFB3 which was made from phenol, urea, and formaldehyde with a molar ratio of 1: 0.5: 1.7, respectively, and exhibited a similar methylene structure with PF resin. Then, the formulated resins were applied to produce particleboard. Mechanical properties of the produced particleboards were determined and compared with those of ones which were prepared with PF resin as the control treatment. The findings demonstrated that the substitution of urea increased the dry internal bonding strength and modulus elasticity but reduced the internal binding strength of the produced particleboards following a two-hour immersion into boiling water. The findings revealed that the mechanical properties of the particleboards produced with PUFB3 resin were comparable with the control treatment, and the formulation of phenol, urea, and formaldehyde with the molar ratio of 1: 0.5: 1.7 was selected as the optimum treatment for outdoor condition and under load. In addition, the particleboards produced with PUFD1 resin which was formulated of phenol, urea and formaldehyde with the molar ratio of 1: 0.5: 2.5 exhibited standard properties for application in outdoor conditions without load.