Journal of Wood and Forest Science and Technology
Year:2011 | Volume:18 | Issue:2|Papers Count:11

Important producer countries of wood and paper products are identified by this study. Identification of these countries is Important for trade of wood and paper products. Ranking of different regions of the world was done using mean values of the production based on FAO 10 years reports from 1998 to 2007. Results showed that the production value for the major part of the products was almost constant during the studied period. Developed countries such as: USA, Canada, China and Germany were the foremost producers of wood and paper products and even the production rate of USA and Canada is slightly lower than the total production of all other countries of the world. These countries have kept their production rate as the years before 1998. The global harvesting of non-coniferous round woods was higher than coniferous round woods, but world production of the non-coniferous industrial round woods became less than that of coniferous industrial round woods in the last years of the studied period. Some Asian countries such as Indonesia and Malaysia have been willing to produce secondary products instead of raw materials. These countries are among the 10 top countries in manufacturing of the products such as wood-based panels and pulp and paper in the studied time period.

The purpose of this reseach was to examine the influence of resin consumption gradient and press time on the physical and mechanical properties of particleboard produced from citrus tree residues. Four resin consumption gradients, 0, 2, 4 and 6% difference between surface and core layers (10-10%, 11-9%, 12-8% and 13-7%) and two press times of 4 and 5 minutes were applied and totally 24 laboratory boards were produced. The mechanical and physical properties of boards were measured and the results were analyzed using ANOVA method. The results showed that applying the resin consumption gradient of 2%, the MOR of the boards was improved. However, MOE of the boards increased as the resin consumption gradient increased and the maximum was observed at 6% resin gradient. The results indicated that at resin consumption gradient of 2%, higher IB was reached which was significantly different compared to other resin gradients, but at higher resin consumption gradients lower IB was measured. The thickness swelling of the boards showed irreversible behavior to IB of the boards and as the resim consumption raised to 2%, lower thickness swelling was observed which was significantly different with other resin consumption gradients and further improvement was not observed at higher resin gradients.

In this study, the effect of nano-silver (Ag) treatment on the drying rate and final moisture gradient of poplar wood was investigated. Poplar (Populous nigra) boards with green dimensions of 100×70×50 and 20 mm were treated with nano-silver (Ag) suspension by spraying and immersion method. Two concentrations of nano-silver suspension, including 20 and 100 ppm were used. Then, the boards were conventionally dried at a constant dry-bulb temperature of 60oC and relative humidity of 40%. The boards were coated on their four surfaces using epoxy resin to confine the moisture transfer along the board thickness. In addition, the temperature gradient along the board thickness was measured during drying. Results showed that in contrast to control samples, in the nanoparticles-treated boards, particularly those immersed in 100 ppm nano-silver, a reverse temperature gradient developed. The moisture gradient in the 50 mm-thick boards treated by 100 ppm nano-silver was more homogenous than that in control boards, however, no difference was found between the other treated boards and control boards. Despite reverse temperature gradient through the thickness of treated boards, there was no significant difference in drying rate between the control and treated boards. Thus, it can be claimed that in the medium temperature wood drying process, the temperature gradient cannot be considered as a driving force for moisture transfer and therefore the bulk flow due to temperature gradient (Soret effect) can be neglected.

Soda and soda-AQ pulping of corn stalk applying different charges of active alkali and pulping time was studied. The average value of fiber length, diameter and cell wall thickness were measured as 1.03 mm, 23.64 µm and 5.26 µm, respectively. The content of alcohol-acetone extractives, cellulose, lignin, extractives soluble in 1% NaOH and ash content of corn stalk were determined as 15%, 51.2%, 23%, 45.95% and 2%, respectively. Pulping with four levels of sodium hydroxide (12, 14, 16 and 18%, based on NaOH), and two cooking times (15 and 30 minutes) and constant cooking temperature at 145oC was performed. 0.1% AQ was added to soda/AQ cooking liquor. After analyzing the pulping yield and kappa number, two pulps were selected (NaOH, 12, 18%, cooking time, 15 minutes and cooking temperature, 145oC) as brown and bleachable stock, respectively. Eventhougth addition of 0.1% AQ showed no significant effect on pulping yield, but its effect on paper strength properties was significant. The result of handsheet evaluation revealed that the strength of pulp produced applying 18% NaOH, 0.1% AQ, and 15 minutes pulping time with breaking length of 8.21 km, and 80.59 N.m/g tensile index was superior to other pulping conditions. The tear index of the pulp produced applying 12% NaOH, 0.1% AQ and 15 minutes pulping time was determined as 10.60 mNm2/g. The burst index of pulp produced using 18% NaOH, 15 minutes pulping time without AQ addition, was the highest.

The effect of commercial xylanase enzyme in prebleaching of bagasse kraft pulp was investigated. Xylanase enzyme from Trichoderma viride was added to pulp at various doses of 5, 10, 25 and 50 IU/g pulp for reaction time 2h and then the enzyme treated pulp was bleached in D1ED2 sequences (using Dioxide chlorine 4, 6, 8, 10%+Alkaline extraction+Dioxide chlorine 2% as active chlorine). The results showed that enzymatic treatment improved brightness and opacity and decreased yellowness, kappa number and revolution of refiner for given freeness of bleached pulp significantly (P<0.01). Maximum of brightness and opacity and minimum of kappa number were related to 25 IU/g pulp treatment, which had about 13.1%, 1.46% and 2.23 unit significant differences in comparison with those of the control sample, respectively. Minimum of yellowness was related to 50 IU/g pulp treatment which had about 7.32% significant difference as compared with control sample. Regard to the obtained results, the 25IU/g pulp treatment could be suggested as optimum treatment.

Due to the problems of deposition of sodium silicate on the equipment and decrease of the service age of implements, deinking of old newspaper was accomplished using organic complex of Sulvy-x in place of sodium silicate.Sulvy-x was used at four levels of 0.3, 0.5, 0.7 and 1% on the basis of oven dry waste paper and chemical deinking was done. The effect of various charges of Sulvy-x was investigated and on optical and physical properties of deinked pulp compared with those of control sample (ONP recycled using 2% sodium silicate) and its optimum usage was determined. The results of optical properties showed that the brightness of paper increased to 50.8% ISO and the yellowness decreased to 11.96% ISO by increasing of Sulvy-x charge up to 0.9%. Also, lower charge of Sulvy-x (0.3%) resulted the highest opacity of 98.63% ISO. The results of physical properties indicated that the caliper of paper reduced to a minimum value of 109.8 mm. Higher charges of Sulvy-x in deinking process resulted the paper with the higher density. The highest density of 0.546 g/cm3 was observed using 0.9% Sulvy-x. Also, deinking of old newspaper with 0.3% and 0.7% Sulvy-x resulted the pulps with the highest freeness as 435 ml, CSF. In general, using different amount of Sulvy-x in place of sodium silicate resulted the papers with similar brightness, higher opacity and lower caliper compared to those of control sample. However, the paper with higher brightness and density, lower yellowness and desirable opacity could be produced using 0.9% Sulvy-x in chemical deinking of old newspaper.

This study sougth to the effect of OCC pulp fractionation on produced paper strength properties improvement. Using a pressure screen, OCC pulp was devided to tow distinct fractions of accept ratio (short fibers) and reject ratio (long fibers) in accordance with optimum condition of fractionation based on the previous studies. In the next stage, long fiber stream was refined and recombined with short fiber stream based on different ratios. Then, hansheets were made of notified recombined pulp, inlet OCC pulp and refined long fiber pulp samples. The results of physical and mechanical tests showed that by increasing short fiber ratio up to 50%, strength properties of produced paper were higher than those of inlet OCC pulp. This indicates the positive effect of fractionation on increasing pulp refining potential and paper strength properties improvement. On the other hand, by not refining 50% of the inlet OCC pulp (short fiber stream), operation capacity of refining process and refining energy consumption increases and decreases, respectively.

Walnut is a hardwood tree which covers a wide area of the plantation forest and gardens. The objective of this study was the separation and identification of compounds produced from pyrolysis of walnut wood at fixed bed reactor under an inert gas atmosphere (nitrogen) at 350oC for 20 minutes. The separation and identification of compounds from bio-oil treated with N, o-bis (tri methyl sailil) tri fluoro acetamid (BSTFA) were done by using gas chromatography/mass spectroscopy (GC/MS) technique. Ten compounds were totally identified. The most important compound identified in wood at this range was levoglucosan and a-L-galactofuranosid. The other important compounds observed at 350oC were propanoic acid, tetracozan, octamethyltrisiloxane, sailan, 1, 2, 3 butan triol and Tetracosane.

In this research, water and steam absorption behavior and also effect of maleic anhydride polypropylene (MAPP) on these behaviors in wood fiber-polypropylene composite were compared. For this purpose, the composites were manufactured from 60% fibers and 40% polypropylene in presence and absence of MA. The oven dried samples with dimensions of 2.5×2.5×1 cm were immersed in distilled water and exposed to water steam. Long-term water and steam absorption and thickness swelling of the composites were studied. The results showed that the composites exposed to water steam exhibited higher water absorption and thickness swelling than those immersed in water. The addition of 2% MA decreased steam and water absorption and thickness swelling in studied composites.