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The effect of addition of copper nanoparticles to a urea-formaldehyde (UF) adhesive on the physical and mechanical properties of particleboards manufactured from date palm waste (DPW) was investigated. The variable factors in the study included copper nanoparticles in amounts of 6 and 8 wt.% of the dry mass of wood, pressing durations of 5 and 6 min, and pressing temperatures of 150 and 160°C. The physical and mechanical properties of manufactured boards were measured according to EN standards. The results showed that the addition of copper nanoparticles to the UF adhesive considerably improved the physical and mechanical properties of the boards and shortened the pressing duration. The boards manufactured with 6 wt.% copper nanoparticles in a dry mass of wood mixed with the adhesive and pressed at a temperature of 160°C for 5 min had mechanical properties exceeding the EN312-2 standard levels.

Improving effects of recycled polyethylene on dimensional stability, mechanical properties, and reduction in adhesive consumption of particleboard made from canola residues were studied here. Canola residues were consumed at 0, 30, and 50 % consumption levels, based on the dry weight of wood particles. Recycled low-density polyethylene was also consumed at two levels of 20 and 30 %. Urea-formaldehyde resin was used for all treatments at three levels (6, 8, and 10 %). Results showed that polyethylene had significant improving effects on all the physical and mechanical properties. Increase in canola content, however, increased modulus of rupture and modulus of elasticity due to the more slenderness ratio of canola residue, but it decreased the internal bond and physical properties because of the higher specific surface area of canola particles. Properties of the panels made from 30 % canola residues, 30 % polyethylene, and 8 % ureaformaldehyde resin were in compliance with the EN 312-2 standards. It can be concluded that the improving effects of recycled polyethylene can compensate for part of the ureaformaldehyde resin, and therefore, lower urea-formaldehyde content can be used, lowering the production costs due to high-value urea-formaldehyde resin. At the same time, the potentiality of formaldehyde emission into the atmosphere would also be decreased.

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