Characteristics of particleboard made from recycled wood-waste chips impregnated with phenol formaldehyde resin

The main purpose of this study was to manufacture water-resistant particleboard for use in kitchens and bathrooms, and as flooring-based material and in outdoor environments. The chips were from recycled wood wastes of different wood species. The chips were divided into coarse chips with dimensions of 5–8 mesh and fine chips of 8–20 mesh, then, these chips were immersed in water-soluble phenol formaldehyde (PF) resin solution at concentrations of 4.5%, 6.5% and 10%. After 5 min, they were removed from the PF solution and dried in an oven until in a half-hardened condition. Three-layer mats with target densities of 0.70 and 0.80 g/cm3 were formed by using fine chips for the face layer (25%) and back layer (25%) and coarse chips for the core layer (50%). A conventional hot press was used for fabrication of the particleboard, and the temperature, pressure and pressing time were 453 K, 2.9 MPa, and 5 min, respectively. The nominal dimensions of particleboard were 500×500×12 mm (thick). Result showed that the PF resin absorption content of chips (RC) increased linearly with an increase in the concentration of PF solution. Their relationship could be represented by the linear regression formula. The bending strength, internal bonding strength, and thickness swelling (%) of the PF-impregnated particleboards exhibited excellent performances compared to those made in the past, and the retention rate (%) of the modulus of rupture (MOR) and modulus of elasticity (MOE) of PF-impregnated particleboard after treatment in hot water (343 K) for 2 h were maintained at 48.7–84.5% and 49.2–82.7%, respectively. Characteristics of the ultrasonic velocity in the mechanical direction were similar to those in the vertical direction. In addition, there were significant relationships between the ultrasonic velocity and the mechanical properties of the particleboard, and this meant that we could evaluate the properties of the particleboard using ultrasonic velocity.