Hybrid acacia, produced from natural crossing between two introduced timber species Acacia mangium and A. auriculiformies has been studied for assessing the suitability of plywood and particleboard manufacture. It was found that 1.5 mm thick smooth and figured veneer can be made and dried easily. Three-ply plywood were made using veneer of this species bonded with liquid urea formaldehyde glue of 50% solid content extended with wheat flower and catalyzed (ammonium chloride) with 2% hardener under the specific pressures, viz., 1.05, 1.40 and 1.76 N/mm2 in three replications at 6 minute press time and 120°C press temperature. Dry and wet shear test were conducted on the sample and their shear load at failure per unit area and percentage of wood failure were determined. 1.76 N/mm2 pressure for the manufacture of ply wood is found to be the best. The particleboard was tested for determining the strength and dimensional stability. The bending strength passed the standard specification, tensile strength was found to be low as per Indian standard. DOI: http://dx.doi.org/10.3329/jbas.v36i2.12960 Journal of Bangladesh Academy of Sciences, Vol. 36, No. 2, 171-176, 2012

Woods of Albizia richardiana has been studied for assessing the suitability for plywood and particleboard manufacture. It was found that 1.5 mm thick smooth and figured veneer can be peeled and dried easily. Three-ply plywood were made using veneer of this species bonded with liquid urea formaldehyde glue of 50% solid content extended with wheat flour and catalyzed (ammonium chloride) with 2% hardener under the three specific pressures, viz,1.05 N/mm2, 1.40 N/mm2, 1.76 N/mm2 in three replications at 6 minute press time and 120°C press temperature. Dry and wet shear test were conducted on the sample and their shear load at failure per unit area and percentage of wood failure were determined. 1.05 N/mm2 pressure for the manufacture of plywood was found to be the best. The physical and mechanical properties of Albizia richardiana wood particleboard were studied. The particleboards were tested for determining the strength and dimensional stability. The tensile strength 0.56N/mm2 passed the British and German standard specification, bending strength (modulus of rupture10.80N/mm2) was found nearest to Indian Standard but low German and British standard specification.

A study was conducted on the preservative treatment of Acacia mangium poles to determine the treatment schedule for outdoor use. The poles contained 52.27% sapwood which is generally perishable by wood destroying organisms. In this study, 27 poles were treated with aqueous solution of 10% CCB by Lowry empty cell process. Three different pressures and three time periods were applied to evaluate the depth of penetration and amount of retention of the preservative chemicals. It was observed that preservative chemicals penetrated the entire sapwood portions of the poles which are the main criteria for the protection of poles. But, on the other hand, no significant increase was observed in penetration with the simultaneous increase of pressure and time period, although the retention of the preservatives was found to increase significantly. The highest retention of 22.98 kg/m3 and full penetration of sapwood was observed after 1.04 N/mm2 pressure for three hours. It is expected that the applied pressure and time period are adequate for protecting the Acacia mangium poles from wood destroying organisms in outdoor condition.

The study was conducted to find out the suitability of making particleboard using nipa palm (Nypa fruticans) stem wood and rajkoroi (Albizia richardiana) wood chips. Particleboards were fabricated at six different ratios of nipa palm stem and rajkoroi wood chips such as 100:0, 75:25, 50:50, 25:75, 10:90 and 0:100. Characteristics of particleboards such as modulus of rupture, internal bond strength, water absorption, thickness swelling and moisture content were measured. Results shows that particleboards made from 100% rajkoroi wood chips have the highest static bending properties and highest tensile strength properties of other particleboards but 100% nipa palm stem wood chips have the lowest static bending and lowest tensile strength properties of other particleboards. 10% nipa palm stem wood chips particleboard have the highest bending strength and tensile strength is better than 100% nipa palm stem wood chips and other mixing chips of particleboards. Mechanical, water resistance and dimensional stability properties were tested according to Indian standard specification. Tensile strength passed the British and German standard specification and nearest to Bureau of Indian Standard, bending strength was found nearest to Indian Standard but lower than German and British Standard specification. Strength property of rajkoroi wood chips particleboard is higher than nipa palm steam wood chips particleboard but dimensional stability is lower than nipa palm steam wood chips particleboard.

Logs of Khaya anthotheca wood has been studied for assessing the suitability of plywood and particleboard manufacture. It was found that 1.5 mm thick smooth and figured veneer can be made and dried easily. Three-ply plywood were made using veneer of this species bonded with liquid urea formaldehyde glue of 50% solid content extended with wheat flour and catalyzed (ammonium chloride) with 2% hardener under the specific pressures, viz, 1.05 N/mm2, 1.40 N/mm2, 1.76 N/mm2 in three replications at 6 minute press time and 120°C press temperature. Dry and wet shear test were conducted on the sample and their shear load at failure per unit area and percentage of wood failure were determined. 1.05 N/mm2 pressure for the manufacture of ply wood was found to be the best. The physical and mechanical properties of K.anthotheca particleboard were studied. The particleboards were tested for determining the strength and dimensional stability. The tensile strength (internal bond strength 0.68 N/mm2) passed the German and British standard specifications; bending strength (modules of rupture 11.25 N/mm2) passed the Indian Standard but did not pass the German and British standard specifications.