BONDING PERFORMANCE OF STRUCTURAL ADHESIVES ON HEAT-TREATED MIMOSA SCABRELLA AND PINUS OOCARPA WOOD

摘要

Wood adhesives are used to develop various products from wood species, such as Mimosa scabrella and Pinus oocarpa. The variety of adhesives, wood species and treatments make it difficult to find the best combination for use. The objective of this study was to evaluate the performance of structural adhesives on M. scabrella and P. oocarpa wood. Wood samples were heat treated in nitrogen atmosphere at 180, 200 and 220 degrees C for one hour. The mass loss upon heat treatment, equilibrium moisture content and chemical composition of the wood were evaluated. The wood was bonded with polyurethane/E23, resorcinol formaldehyde and polyvinyl acetate (PVA) adhesives, with the application of 12 kgf.cm(-2) and grammage of 200 g.m(-2). Heat treatment reduced mass, equilibrium moisture and holocellulose content, and increased the lignin and extractives contents of M. scabrella and P. oocarpa. The heat treatment also decreased the shear strength and increased the percentage of wood failure with the adhesives evaluated. The shear strength and failure percentage achieved with resorcinol were better and thus this adhesive is the most appropriate one for heat-treated wood bonding.