مجله تحقیقات علوم چوب و کاغذ ایران
سال بیست و سوم شماره 1 (پیاپی 28، بهار 1387)

The application of regressions models for pridicting physical and mechanical properties of laboratory produced particleboard was studies. In order to study the influence of mat moisture content gradient, particle geometry, press time and temperature, 108 boards were produced.Regressions model indicated that particle geometry significantly influenced board MOR, increasing the slender ratio of particles, improved MOR. Regressions models of MOE indicated that both particle geometry and mat moisture content gradient significantly influenced board MOE, and increasing the slender ratio of particles and mat moisture content gradient, increased MOE. regression model of IB indicated that all of the variables have significantly affected IB. However, in this case, increasing mat moisture content gradient, particle geometry reduced IB and press time and temperature increased IB, moisture content gradient and particle geometry had more effective.The results indicated that moisture content gradient and press time significantly influenced the regression model of thickness swelling after 24 hours soaking in cold water.

This study has been performed in order to determination of optimum refining of paper made of recovered Kraft liner. Recovered Kraft liner has been prepared from anzali city. After shredding into 5 centimeter pieces, the papers were soaked in distillated water in pail. After 7 days fibers was separated of each other by disintegrator and freeness for each pulp before and after refining were measured. They were refined in revolutions of 3000, 6000, 9000, 12000 by PFI mill. Hand sheets were made from each revolution in order to TAPPI standard T 205om-95 number, and then were compared with control sample. Analysis of variance of waste papers were conducted using completely randomized design, then mean values were compared, using Duncan’s test, and finally the normalization equations were used to determine the best sample. Results showed that increasing of refining revolution increased strength of burst, tensile and brightness but decrease freeness, thickness and tear strength at product. Normalization equations showed that the best papers made from refining revolution of 9000.

In this study, MDF was produced from three clones of poplar (P.e. vernirubensis, P.e. costanzo, P.e.561.41). Age clones of poplar were 4 and 12 years. In addition to age variation, the influence of three production variables (steaming time, press time and resin content on MDF properties were investigated. Variations of each variable were as follow:- Steaming time (5, 10, 15 minutes)- Press time (3, 4, 5 minutes)- Resin content (9%, 11%)Fiber length and fiber diameter of 4 and 12 years old poplar clones (P.e. vernirubensis, P.e. costanzo, P.e.564.41) were measured 746, 25.23, 805, 25.76,751, 25.44 and 902, 31.62, 995, 29.23, 899, 26.83 micron respectively.MOR, MOE, IB, TS2, TS24 were determined according to DIN standard.Increasing steaming time decreased board's internal bond and bending properties. As expected, boards demonstrated better properties at higher resin consumption. Minimum of boards thickness swelling were obtained at 15 minutes steaming time because of fiber hydrophilic properties were decreased. There are no significant differences between 4 and 12 years old of clones for bending properties and IB of boards. The effect of age variation is only significant difference on thickness swelling of boards which it is lower for 4 years old clones.

In this study the effects of several parameters on the sizing efficiency of test liner using poly aluminum chloride and rosin under neutral condition in reverse and premixing sizing processes were investigated. The results indicated that the individual effects of poly aluminum chloride amount, rosin amount, interval time as well as interaction effect of poly aluminum chloride -rosin amounts in both sizing processes affect significantly sizing performance. The most important variable was the poly aluminum chloride amount. The effect of poly aluminum chloride amount on the sizing efficiency depended on the properties of fiber surfaces. This study showed that the interval time on the sizing efficiency is significant. To obtain an identical degree of sizing, it is possible decrease the amount of poly aluminum chloride and rosin amounts by increasing the interval time. In addition, the results confirmed two different mechanisms involved in the premixing sizing process.

In this investigation, the effect of paraffin content and press time and temperature on practical properties especially surface roughness of particleboard is studied. The variables such as paraffin content at 0, 1& 2 percent, press temperature at 170° and 180° C and press time of 4 and 5 minutes were investigated. Modulus of rupture, modulus of elasticity, shear strength, water absorption and thickness swelling after 2& 24 hours soaking in water & surface roughness were measured.The results indicate that there is no significant difference on the influence of paraffin content on either MOR & MOE of the particleboard. But increasing paraffin content decreased shear strength of panels.However, addition of paraffin reduced water absorption and thickness swelling.Press temperature had no significant influence on measured properties, but this variables increased surface roughness. Increasing press time, improved MOE, but showed no significant influence on other properties.

The effect of Apple pruning wood particles in mixed with industrial wood particles for particleboard manufacturing was studied. One layer laboratory panels with density of 0.6 gr/cm3 with two variables amount of Apple pruning wood particles content (0/100, 15/85, 30/70, 45/55 percent weight of Apple pruning particles/wood particles) and a press time of 5 and 7 min were produced. The physical and mechanical properties of panels were measured. The results showed that the amount of Apple pruning wood particle had significant influence on the most physical and mechanical properties of panels such as MOR, MOE, IB, TS and WA while they were improved as the Apple pruning wood particles increased. The results also indicated that press time had significant influence on the IB and TS of panels and they were increased as the press time increased.

In this study, effects of press temperature and press time on the physical and mechanical properties on the OSB has made from Aspen were investigated. Two levels of press temperature 175ºC and 185ºC and two levels of press time 5 min and 6 min were applied as variables for manufacturing boards. Mechanical and physical properties such as bending strength, internal bond, water absorption and thickness swelling were measured. results showed that, increase in press temperature and press time causes significant increase on bending strength, internal bond, water absorption and thickness swelling. The best boards were made of press temperature of 185ºC and press time 5 minutes.

Okaliptus is a fast –growing and light – liking tree that its trunk is smooth and is shelled spontaneously. n a short time its diameter and height increase.for its fast growing. So that turing it into things is difficult Fiber s traction is high and deksity is 0.55 to 0.58 a square centimeter.The samples were prepared from the branches and trunk of Ocalyptus Kameldolensis with the average old of three years, from Jiroft region in Kerman province. After ordaining the age and having samples from the same age, some discs were prepared for cutting to measure fibers.Making ready and suspension of fibers were done in Fraklin method. Measuring amaout of lignin was done to standard no: T222- om – 88 and TAPPI guide directions. Measuring cellulose was done according to Nitric Acid method and due to standard No: T264 – om – 88, and TAPPI guide directions. Due to results the length of trunk fibers was 811.36 and branches was 845.68 micro meters.Diameter of trunk fibers is 19.3 but branches 15.64, these amounts don,t have a meaningful differnce the level of 5&1 percent. Diameter of the carity of rrunk fibers was 10.71, but branches 3.44 at the level of 5&1 percent, they don,t have a meaningful difference. The amount of extracted articles of trunk is 4/5 but branches 2.3 percent, and amount of lignin in trunk was 35.66 but in the branch 24.66, and amount of cellulose in trunk was 55.66 and the branch 46.81 percent which at the level of 5&1 percent have a meaningful difference. The amount of Ashes from trunk was 0.73 but from the branch 0.88 that at the level of 5&1 percent, don,t have a meaningful defference.