Iranian Journal of Wood and Paper Science Research
Year:2015 | Volume:29 | Issue:4|Papers Count:22

This study investigated the effect of bark content on the physical and mechanical properties of kraft pulp from Populus deltoids wood chips. Three Populous Deltoids trees at the same age were randomly selected and felled at Shastkalate research forest, Gorgan University of Agriculture and Natural Resources. One short bolt was taken from each tree. The bolts were manually debarked and wet weight of wood and bark from each bolt was determined. Then weight ratio of wood/bark was calculated for each bolt. Kraft pulp was prepared using following pulping condition: sulfidity 25%, AA: 20%, temperature: 170oC, l/w: 6/1 and bark content as 0, 6, 12, 18 and 24%, (w/w). Pulp with kappa number of about 20 was prepared from each treatment, and then each pulp was separately beaten to reach freeness value around 350 ml, CSF. In order to determine the effect of bark content on yield, kappa number and the physical and mechanical properties of the pulp, F test was used in completely randomized, and for comparison of the means, dunkan test was used. Yield and kappa number of the pulps were as 50.32-52.03% and 20.37-21.17, respectively. With increasing the bark content, density of paper was decreased and the lowest value was 0.477 g/cm2 for bark contained pulp. Also, with increasing the bark content to 18%, strength properties of the related pulp was improved.

The aim of this study was to use precipitated calcium carbonate modified by cationic starch as the filler in writing and printing paper and compare the strength properties of the resulting paper with similar paper using conventional filler (unmodified). One of the limitations of adding fillers to paper is the reduction of the mechanical strength of paper because of reduction in bonding between fibers. In this study with purpose of maintaining the strength of paper, the surface charge of precipitated calcium carbonate was modified and the resulting filler was used. The cationizing condition of cationic precipitated calcium carbonate was selected as; 90oc temperature, 3 hours and 55% water content of cooking process. Loading amount of starch was 9, 12 and 15 percent (w/w) based on precipitated calcium carbonate. Paper was made at three level; 10, 16, 30 percent of filler in paper sheets and compared with conventional fillers. Results indicated that papers containing modified filler retained more filler than those with unmodified filler, at either 20% and 30% filler dosages. Papers contained modified filler showed higher mechanical strength index as compared with papers containing conventional fillers.

Old corrugated container (OCC) recycling generates large volume of effluent which is heavily loaded with pollutants. Its treatment is very difficult and complicated due to the presence of various pollutants and certain chemical with complicated structure. In this study, the treatment of OCC recycling effluent was investigated using nano TiO2 and the treated effluent parameters such as COD, TDS, TSS, TS, EC and turbidity were measured. Nano TiO2 was applied at 0.5%, 1%, 1.5% of the effluent volume and the pH was adjusted at either 5, 9 or 7.3 (as received from mill). The results showed that the nano TiO2 and pH are effective on all of the parameters and the effect was statistically significant at 99%, but the effect of variables on EC was not statistically significant. The effect of pH on all of parameter was statistically significant at 99% expect on EC. Optimum condition was pH of 9 and the 0.5% and 1%. nano TiO2 dosage. At this treatment condition, COD, TDS, TSS, TS and turbidity were reduced by 47.5, 38.7, 98, 70.4, and 97.7 % respectively.

In this study, the structure of Soda lignin (soluble fraction in ethanol) and dioxane lignin produced from bagasse were studied by using derivatization followed by reductive cleavage (DFRC) method and some techniques including gel permeation chromatography, gas chromatography-mass spectrometry and 13C-nuclear magnetic resonance spectroscopy and the results were compared. These comparative results show that the main monomeric compounds are obtained from the cleavage of b-O-4 bonds of lignins. The components obtained from dioxane lignin and Soda lignin are guaiacyl, syringyl and p-hydroxyphenyl structures with different proportions. However, some differences have been observed in both lignins, including the variety of structural units in dioxane lignin is greater than Soda lignin. In other words, soda lignin degradation and the structural components are closer together and are more uniform structures. The average molecular weight of dioxane lignin, is greater than Soda lignin, which is due to Soda lignin wide chemical degradation during industrial pulping processes and therefore it has less dense structure. These observations indicate that a mild method for lignin separation from a lignocellulosic material caused less damage and changes in lignin structure. Therefore, in structural studies, dioxane lignin can actually be used as an appropriate representative of the lignin.

The effect of layering and glue coverage rate in layered products made from poplar wood was studied using non-destructive free vibration test. 120 samples with nominal dimensions of 2.5×2.5×45 cm without any obvious deficiencies and defects were selected and free flexural vibration in free-free bars were performed on selected samples. Samples were longitudinal cut in three thinner tangential layers and jointed together again using Poly Vinyl Acetate glue. The specimens were divided into four groups according to glue coverage rates, which one group was fully glued and 3 groups were carrying some glue deficiencies in different rates. Manipulated samples were tested again in above mentioned test. Results indicated that shear moduli compare to modulus of elasticity is a more sensitive parameter to evaluate glue efficiencies in laminated beams but concerns remained due to blind points in flexural vibration nondestructive method.

The Avicennia tree genus was named in honor of Ibn Sina, a 10th century Persian philosopher and physician known more commonly as Avicenna. In this paper, wood anatomical property of Avicennia marina (Acanthaceae) which is one of the most important species of Iranian Mangrove forest has been investigated. Wood samples were taken from trunk of three adult trees, and then micro-sectioned and dyed by Astrablue, Safranin and finally mounted by Canada balsam. Also wood chips (match stick size) were placed in equal parts of glacial acetic acid and hydrogen peroxide and placed in the oven at 60oC for 48 hours. Then, after defibration, one drop of fiber slurry was deposited and stained on microscope slides. The presence of concentric included phloem which is surrounded by lignified conjunctive parenchyma (axial parenchyma) and scleroid bands are the most important anatomical characteristics of Avicenna marina cells. The variability of anatomical characteristics of Avicennia marina in different references can be attributed to growing site condition (altitude and latitude).

In this research, the effect of wetwood and blue stain on the drying rate and fluid transport coefficients of poplar wood (P. nigra) was evaluated. For this purpose, five boards with dimensions of 150 × 35 × 45 mm were cut from wetwood, normal wood and stained wood areas of freshly cut lumbers in Taleghan region and then dried to the final moisture content of 8 percent inside a laboratory dryer at temperature of 50oC, relative humidity of 60% and air velocity of 1 m/s. Overall, drying time was 120 h.After drying, the transverse permeability and diffusion coefficients were measured. The results showed that the wetwood do not impose decreasing effect on the drying rate of poplar wood. However, it reached to the final moisture content slower due to higher initial moisture content. Also, the wetwood had no significant effect on the transverse permeability but reduced the diffusion coefficient. In contrast to the wetwood effects, the drying rate, permeability and diffusion coefficients were increased due to the blue stain.

In this research the influence of using waste Poly Ethylene Terephthalate on the mechanical and rheological properties of wood flour filled PP composites has been studied. PET contents varied from 10-33 wt%. Mechanical properties were characterized by tensile testing, while their fracture resistance was determined by impact measurements. The melt rheological behavior of the composites was also studied by a rheometer in the oscillatory mode and dynamic rheological properties such as complex viscosity, storage modulus, loss modulus and damping factor were evaluated at 190oC. The results showed that stiffness increases by adding waste Poly Ethylene Terephthalate. PET when added in low concentrations, caused tensile strength to be lower than that of PP composites filled with pure wood flour. Increasing the concentration of waste PET, led to composites with higher tensile strength. The samples containing waste PET showed higher complex viscosity and storage modulus than composite without PET. Likewise, it was observed that the damping factor in the PP/Wood composite decreased by incorporating waste PET to the composition.

Iran is not rich in forest land and only 7.5 per cent of country is covered by forest. Therefore Iran has to import wood based panel annually. It is estimated that 100.000.000 Date Palms trees covered an area at about 770.000 hectares around world, and Iran has got 220.000 ha. Because of several reasons Date palm trees should be pruned and each tree produce 10-20 kg residues annually. In this study, for making boards Date Palm pruning residues as raw material and employed UF resin as the binder. Steaming time (5 and 8 Min.), steaming temperature (135 and 145oC) and press time (1, 2 and 3 Min.) were used as variable factors and three boards were made in Pilot plant scale for each combination of variables. Samples of all made boards were tested by the methods of EN to obtain mean values of bending strength, and internal bond strength (I.B). In addition samples of each type of board were tested for thickness swelling after soaking in water for 2 hours and 24 hours respectively.The results of this study show clearly that boards have higher mechanical properties than the MDF property requirements which are recommended by EN standard.

In this study, fracture characteristics of wood-polymer under mode I were investigated by double cantilever beam. In this regard, the properties of furfurylated wood specimens with three different levels of furfuryl (20%, 30% and 65%) were evaluated in both RL and TL systems. Results indicated that load-displacement curves from mode I fracture specimens were changed by furfurylation so that it was much clear on curves of TL system. These changes not only included curve slope in elastic and proportional limit zones, but also fracture zone and initiation of crack growth were also affected. Furthermore furfurylation and raising its content on both systems and especially on TL one, caused to change in stress intensity factor, KIC, and critical energy release rate, GIC. In both systems, GIC were severely increased by increasing the furfuryl contents. This criterion demonstrated that the wood- polymer showed much toughness under mode I fracture. Moreover, variation of KIC values due to furfurylation at both systems was different with that of GIC. At the RL system, ascending trend was observed at KIC and GIC values by increasing furfurylation levels. But at TL system, KIC was decreased by furfurylation and this criterion enhanced by increasing of furan polymer in the cell wall. Generally, results of this research show that fracture toughness of wood is highly affected by furfurylation.

In this study, the effect of three levels (3%, 4%, 5%) of hydrogen peroxide and two levels (2%, 3%) of sodium hydroxide on bleaching of tobacco stalks (Nicotiana tabacum L. ’PVH 19’) soda pulp was investigated. Tobacco stalks were pulped using 22% alkali at 170oC for 100 minutes. The produced pulp showed 37.1% yield and kappa number of 62. Bleaching process included two stages: chelating and alkali peroxide bleaching. Results indicated that both brightness and kappa number decreased by increasing sodium hydroxide and hydrogen peroxide level. The results of 3% caustic soda and 5% hydrogen peroxide treatment without chelating stage indicated that initial chelating stage significantly affected the brightness, kappa number and yield of the bleached pulp, and this treatment showed the lowest brightness and the highest kappa number and yield among all treatments. Finally, 3% caustic soda and 5% hydrogen peroxide treatment with initial chelating stage had the highest brightness (44.50%) and the lowest yield (83.20%) was selected as the best treatment.

In this study the effect of different NDT methods on dynamic properties (flexural vibration of Timoshenko beam theory and longitudinal vibration method) of beech wood were evaluated. Twenty nine clear samples with nominal dimension of 2×4×36 cm were selected and bending vibration in free-free beams and longitudinal vibration tests was performed on the samples. Results showed strong correlation between dynamic Young’s modulus and acoustic coefficient measured with both longitudinal vibration and flexural vibration method. The measured damping factor values were significantly higher in flexural vibration compared to longitudinal vibration method, While the acoustic converting efficiency values from flexural vibration was smaller than values of this factor in longitudinal vibration method. There was good correlation between dynamic shear modulus of elasticity from flexural vibrations and dynamic modulus of elasticity in both methods. This finding provides possibility of estimating the shear modulus of elasticity values based on dynamic Young’s modulus of elasticity values from longitudinal vibration test. The results also indicated the existence of good correlation between the phase velocity in first to third modes from the bending vibration. In addition there was good correlation between sound velocity from longitudinal vibration and the phase velocity in first to third modes from the bending vibration.

This research was carried out to identify and compare the organically chemical components in the wood and bark extractives of Eucalyptus camaldulensis. Three healthy trees were cut from Nowshahr forest and samples were selected. The samples were converted into the wood powder. The extraction was carried out with acetone as solvent according to TAPPI standard, and then the extract was transferred to the ballon and the BSTFA catalyst was added to be injected to the GC/ MS. Identification of components was done according to the retention time curve, calculation of Kovats correlation and Adams table. Out of 13 components in the bark of this tree and 18 components in that wood, 2 constituents such as Bis (2-ethyl hexyl) phthalate and hexadecanoic acid were detected in both bark and wood. The most important of chemical component in the bark is (2 ethyl hexyl) phthalate (98.72%) and 2-Pentanone (57.41%) was important component in the eucalyptus wood.

In this study the possibility of using different ratios of urea formaldehyde and melamine formaldehyde for manufacture lightweight particleboard using expanded polystyrene (EPS) was investigated. Experimental panels were made at 30 percent lighter than common particleboard with 25 millimeters thickness and industrial made wood particles. Urea formaldehyde and melamine formaldehyde with two ratios of melamine to urea, 40 to 60 and 20 to 80 were selected as adhesive. Analysis of results using averages of the physical and mechanical properties was used to find the best combination of EPS and resins. Amino plastics adhesives showed good compatibility with expanded polystyrene. As reducing the weight of the panel was the most important target in this work, internal bonding (IB) test was done. Results from the physical and internal bonding tests revealed that characteristics of the lightweight panels made with urea and melamine formaldehyde were consistent with the defined applications in this study. Furthermore, using melamine urea formaldehyde as adhesive imposed positive effects on IB and the highest IB was for the panel made with this resin and minimum EPS content. In comparison with common panels, this new panel with maximum melamine content and hydrophobic EPS showed better results on IB and physical properties.

The objective of this study was to investigate the influence of hydrothermal treatment of walnut (Juglans regia) and Caucasian elm (Zelkova carpinifolia) wood on their acoustic properties. For this purpose, specimens were prepared with dimensions of 360 (L) ×20 (R) ×20 (T) mm. Heat treatments in water were performed at 150oC for 5 hours. Acoustic properties of specimens (specific modulus of elasticity, damping, acoustical coefficient, acoustical conversion efficiency and wave velocity) were measured by free flexural vibration on a free-free bar method. Properties of treated specimens were compared with control specimens. Result showed that hydrothermal treatment improved all acoustic properties of specimens. Acoustic properties of radial and tangential directions of walnut wood did not show significant difference; while in Caucasian elm significant differences was observed between radial and tangential directions. Generally, better acoustic properties achieved in tangential direction of heat-treated Caucasian elm wood. So, it is recommended as a suitable wood to be used in making the sound-boards of musical instruments such as Iranian Santour and Xylophones and also resonator boxes.