Iranian Journal of Wood and Paper Science Research
Year:2007 | Volume:22 | Issue:1 (26)|Papers Count:6

Apparent Density of paper is the most effective physical property which directly and indirectly affects most of the strength and optical properties of paper such as tensile strength, modulus of elasticity, light scattering coefficient as well as the bonded area between fibers. Since paper making variables influences the apparent density of paper, in this study, the influence of ace pulp freeness, and drying conditions are investigated. The influence of three freeness levels of 350,450, and 550 CSF, drying under strain and unstrained, drying temperatures of 100, 150, 200 e and drying pressure of 7 and 10 kg/cm2 are studied. The relationship between paper making variables and apparent density is developed. All measurements of apparent density were analyzed using Minitab 15 and regression model between independent variables was calculated. The results showed that both pulp freeness and drying temperature had the highest impact on apparent density and both factors increased the apparent density. The response of apparent density of the hand sheets dried at 2000C varied considerably and was analyzed thoroughly. Higher pressure increased apparent density of the sheets. The combined effect of variables is also considered. The combined effect of pulp freeness and drying temperature caused lignin softening and delamination. However, the influence of increasing the drying pressure for unrefined and less refined pulp is not significant. Furthermore, for unstrained drying, the influence of freeness on apparent density was more than strained drying. Manufacturing of more desirable quality papers would be possible considering the obtained results and the effect of Apparent Density on paper strength properties.

The effects of different levels of wood particles acetylation and resin content on the physical and mechanical properties of particleboard were investigated. Boards were made within 6 treatments at three different levels of acetyl content (WPGs of 0%, 5.11% and 10.76%) and two levels of resin content (8 and 10 %). The results indicated that by increasing the level of particles acetylation, the density of boards was reduced whereas resin content increased this property. Equilibrium moisture content, water absorption and thickness swelling of the boards were reduced by 15.3%, 26.6% and 14.9%, respectively under optimum conditions as compared with control samples at higher acetylation levels and resin contents. MOR, MOE and IB decreased by increasing acetylation level but increasing resin content from 8 to 10%, improved mechanical properties except for MOR which was not significantly affected by resin content. The result of this research have indicated that using 5.11% acetylation level and 10% resin content, it is possible to produce particleboard having enhanced physical properties with negligible loss of mechanical properties.

The present study deals with effects of CMP fines on optical and physical properties of newsprint papers, for which, different batches for CMP fines (0%, 10%. 20%. 30%) of totally 80% pulp is taken, Where the remaining 20% of imported long fiber pulp was taken as fixed amount.The study focused on surving the effects of CMP fines on optical and physical properties of newsprint paper, after mixing the pulps and making the handsheets.Generally, the results show the increase in CMP fine amount lead to increase, Air Resistance and Opacity and decrease Caliper and Roughness, Also that changes in CMP fines has no effect on Brightness.

Oak (Quercus castaneafolia C.A. Mey) is one of the most important broadleaf species in the Caspian Forests of Iran. The wood of oak is highly appreciated in domestic wood industries especially furniture industry.In this study which is a part of the extensive surveying project of the main wood engineering properties of Iranian woods, the natural variations of strength and related properties of two trees of about 70 years old from Shafarod Forests in Gilan province were investigated.The properties were determined from tests on small clear specimens in the green and dry conditions following the ASTM Standard. The mechanical and physical properties studied include: stress at elastic limits, modulus of rupture, modulus of elasticity and modulus of elasticity in static bending; shear parallel to grain, maximum crushing strength, fiber stress at proportional limit and modulus of elasticity in compression parallel to grain; compression perpendicular to grain and specific gravity.The results of statistical analysis showed that the mechanical strength of the wood was found to be affected by percentage of moisture content of wood specimens, height of sample tree and to some extend by geographical; cal direction.

In this study, MDF was produced from Rice straw. Variables for Medium Density fiberboard making were as following:- Resin content 8, 9.5, 11 (percent based on oven dry weight of fiber)- Press time (4, 5, 6 minutes).There were 9 treatment conditions by combinations of the above factors and three replications for each combination which resulted in producing 27 boards. The other production variables were constant.The anatomical properties of Rice straw such as fiber length, fiber diameter were measured respectively 810, 10.1 micron. L/D ratio of Rice straw fiber was measured 80.2. The physical and mechanical properties of MDF were determined according to DIN standard. The measurements of bending properties and IB of MDF revealed that the highest MOR, MOE, IB were obtained in variables combination of 11% resin content and press time of 6 minute and at this conditions thickness swelling of boards were the lowest.According to Duncans, test method the effects of press times (4 & 5 minutes) and resin content (8% & 9.5%) on bending properties were not significant statistically.

With the aim of measuring the durability of Oak (Quercus castaneafolia), 2x2x45 cm samples were prepared. The treatments were included natural and impregnated with Celcure and creosote. Wood samples with 20 replication installed in 2 zones included Qom and Khozestan provinces. Evaluation of samples were done qualitatively and based on ASTM D-1758-01. According to the results of periodically evaluation, Oak wood is "perishable". All of the Celcure impregnated samples after 60 months and Creosote impregnated samples after 36 months installation in Khozestan, Celcure and creosote impregnated after 41 months in Qom were sound. Stating on longtime result of wood preservative effect needs more investigation.