The influence of moisture content of raw material on the physical and mechanical properties, surface roughness, wettability, and formaldehyde emission of particleboard composite

The objectives of this research were to investigate surface characteristics, physical (thickness swelling) and mechanical (modulus of rupture, modulus of elasticity and internal bond strength) properties, and formaldehyde emission of particleboard composite, as affected by moisture content of wood. Three-layered particleboard panels manufactured from wood particles at five different moisture contents (20%, 40%, 60%, 80% and 95%). Roughness measurements, average roughness (R-a), mean peak-to-valley height (R-z), and maximum roughness (R-y), were taken from the sanded samples along and across the sandmarks using a fine stylus tracing technique. Contact angle measurements were obtained by using a goniometer connected with a digital camera and computer system. Statistical analysis showed significant differences in the surface roughness, contact angle, formaldehyde emission, physical and mechanical properties of the panels following moisture content. Based on the findings obtained from this study, an increase or decrease in the moisture content of wood beyond a certain limit, before chipping operations, negatively affected the wettability and smoothness of particles, and formaldehyde emission, physical and mechanical properties of particleboards. (C) 2011 Elsevier Ltd. All rights reserved.