Physical and mechanical properties of Acacia mangium plywood after sanding treatment

Abstract

Abstract The purpose of this study was to evaluate the effect of sanding treatment on Acacia mangium plywood panel properties. Three layered A. mangium plywood panels were produced from sanded veneer using three different grit sizes: S180, S240 and S320, from medium to ultrafine respectively, with one non-sanded panel as control. Melamine urea formaldehyde resin was unvaryingly used as binder. The outturn of the sanding treatment was observed through a set of evaluations which includes the contact angle test for surface properties, shear strength and static bending for the mechanical properties, and thickness swelling and water absorption rate for the physical properties and dimensional stability. The study shows that almost all of the properties exhibit significant differences at p ≤ 0.05 except for the density and shear test. From the results, the modulus of elasticity of plywood decreases with the increase of grit sizes but shows no significant difference with the control and S240 samples. The S180 samples notably shows an impressive mechanical property with the highest modulus of rupture, albeit the lowest dimensional stability. Nonetheless, the result of this study indicated that the sanding treatment shows a notable increase in the physical, mechanical and dimensional stability of the panel, with the S180 medium grit proving to be adequate and best in improving the plywood panels. As excessive smoothness may negatively affect the wettability itself due to the production of uneven surface and the development of loose fiber that compromises the adherence of the MUF and veneer, the higher grits negatively impacted its treatment on the surface.