The effect of some technological production variables on mechanical and physical properties of particleboard manufactured from cotton (Gossypium hirsutum) stalks

The current study aims to improve properties of particleboard manufactured from cotton (Gossium hirsutum) stalks glued with urea formaldehyde. To this aim, panel density (at three levels: 0,5; 0,65 and 0,8 g/cm3), press temperature (at two levels: 150 and 180 °C) and press closing speed (at two levels: 4 and 8mm/s) were selected as independent variables. The mechanical properties consist of modulus of rupture, modulus of elasticity and internal bonding and physical behaviors such as water absorption and thickness swelling of panels were determined. Results showed that with increasing the density of panels and press temperature modulus of rupture, modulus of elasticity and internal bonding of panels increased, while bending strengths of panels were differently affected by press closing speedcompared to the internal bonding, so that with increasing the press closing speed modulus of rupture increased, but internal bonding decreased. Moreover, increasing panel density and press temperature, water absorption and thickness swelling of panels decreased. The press closing speed affected the waterabsorption and thickness swelling, insignificantly

Effect of Nano bentonite on Fire Retardant Properties of Medium density fiberboard (MDF)

In the present study, Fire – Retarding properties of nano-bentonite in medium density of fiberboard (MDF) was studied. 10% of urea-formaldehyde resin was used as the adhesive of the matrix. Nano Bentonite at 5 levels (0%, 5%, 10%, 15% and 20%) g/kg based of dry weight of fibers was used with the consumption of Urea-Formuldehyde (UF). Press pressure of 150 bar and temperature of 170during 4, 5, and 6 minutes were applied. Density was kept constant at 0.7 g/cm3 in all treatments. The measured properties consisted of mass reduction, inflammation time, fire-endurance, melting time and the burnt area. The results revealed that Nano-Bentonite had significant effect in approving fire retarding properties in medium density fiber board. The best properties at the level of 10% obtained and the same level recommended for industry use. The use of Nano-Bentonite more than 10% decreased the stickiness and the partly surface of fiberboards

The effect of some technological production variables on mechanical and physical properties of particleboard manufactured from cotton ("Gossypium hirsutum") stalks

The current study aims to improve properties of particleboard manufactured from cotton (Gossium hirsutum) stalks glued with urea formaldehyde. To this aim, panel density (at three levels: 0,5; 0,65 and 0,8 g/cm3), press temperature (at two levels: 150 and 180 °C) and press closing speed (at two levels: 4 and 8mm/s) were selected as independent variables. The mechanical properties consist of modulus of rupture, modulus of elasticity and internal bonding and physical behaviors such as water absorption and thickness swelling of panels were determined. Results showed that with increasing the density of panels and press temperature modulus of rupture, modulus of elasticity and internal bonding of panels increased, while bending strengths of panels were differently affected by press closing speedcompared to the internal bonding, so that with increasing the press closing speed modulus of rupture increased, but internal bonding decreased. Moreover, increasing panel density and press temperature, water absorption and thickness swelling of panels decreased. The press closing speed affected the waterabsorption and thickness swelling, insignificantly

Characterization of anatomical, morphological, physical and chemical properties of Konar (Ziziphus spina-christi) wood

The goal of this research is to investigate some morphological (fibre length, fibre diameter, cell wall thickness, Runkel coefficient, flexibility coefficient, slenderness coefficient, rigidity coefficient, Luce\u27s coefficient, solid coefficient), physical (dry wood density, volumetric shrinkage) and chemical (cellulose, hemicellulose, lignin, ash and acetone soluble extractives contents) composition of Konar (Ziziphus spina-christi) wood grown in Hormozgan province, Iran. For this purpose, three normal trees were selected randomly and a disk was cut from each one at breast height. Anatomical inspection revealed that the species was diffuse porous, with distinctive growth rings, simple preformation plate, with polygonal openings, and banded or diffuse-in aggregates parenchyma. The average values of wood dry density, fiber length, fiber diameter, cell wall thickness, Runkel coefficient, flexibility coefficient, felting coefficient, Luce’s coefficient, solid coefficient, rigidity coefficient were 0.926, 52.1, 77.85, 0.57, 163 ×103 μ3 and 0.48. Cellulose, hemicellulose, lignin, acetone soluble, extractives, ashcontents were43.34, 19.98, 33.9, 6.42 and 2.78%, resp