SURFACE ABSORPTION OF PLYWOOD PANELS

Abstract

This work aimed to evaluate the effect of different pressing temperatures on surface absorption of Pinus sp. And Eucalyptus sp. plywood panels. It was produced 8 interior use plywood panels containing 5 veneers, glued together by ureaformaldehyde adhesive at 320 g/cm², pressed at 12 Kgf/cm², with increasing temperatures of 130° C, 148°C, 166°C and 184°C, during 10 minutes. The treatments were arranged in a factorial scheme 2x4, being 2 species and 4 pressing temperatures. The apparent densities of the panels were obtained according to procedures described by ABNT 31:000.05-001/2 standard. The surface absorption test was made in specimen cut both in parallel and perpendicular positions in relation to the fibers, in reduced scale, using an specific apparatus adapted from EN 382-1 (1993) standard for particleboards. The Eucalyptus sp. plywoods presented higher mean value for basic density. The distances achieved by the toluene drop in the plywoods submitted to parallel and perpendicular tests was influenced significantly by species and temperature factors, although the same ones did not present interaction. The Pinus sp panels presented higher absorption potential. In a general way, the increase of the pressing temperature reduced the capacity of panels’ surface absorption.