Estudo da interface madeira-adesivo de juntas coladas com resorcinol-formaldeído e madeira de Eucalyptus grandis w. Hill ex Maiden

Abstract

Understanding the interaction of wood-adhesive substrates is of great importance, because such knowledge will contribute to the making of wood products of good quality. The objective of this study was to evaluate the wood-adhesive interface in photomicrographs, measuring the thickness of glue line main, shear strength test and percentage of failure in bonded joints using wood from the radial and longitudinal positions of Eucalyptus grandis W. Hill ex Maiden. Bonded joints were prepared in accordance with ASTM D 2339-98. To visualize the wood-adhesive interface, two samples of each position (radial and longitudinal) were taken from the log and from each a central hub of 0.5 cm ³ was taken, and this was softened in water and then used to the sliding microtome sectioning. It was possible to see the glue line produced by the connection between the adhesive and wood. The penetration of the adhesive in the anatomical structure of wood could be seen. Both the average thickness of glue line on the main average values of shear strength, basic density and percentage of failures in wood varied in the radial direction of the log. Longitudinally, both the average thickness of glue line and the average values of shear strength and the percentage of failures in the wood varied from one end of the log to the other. Regarding the basic density of wood, these presented the same mean values in the longitudinal sense of the log.