Effect of adhesive on shear strength in young wood glued of Anadenanthera peregrina

The study aimed to evaluate the performance of young wood from Anadenathera peregrina (L.) Speg. in bonding with the adhesives urea-formaldehyde (UF), polyvinyl acetate, resorcinol-formaldehyde, and tannin (TF) adhesives at a 20:80 ratio (TF: UF), using application weights of 200, 250, 300, and 350 g m^-2. Bonding was performed at room temperature (≈ 25-30 °C) and subjected to shear strength tests under tensile load. Chemical analyses of wood was conducted to understand the interaction between the wood and the adhesive. Photomicrographs were obtained to assess potential obstructions within the wood. The adhesion was not satisfactory between A. peregrina wood and the various adhesives at the used, fell below the recommended levels for commercial use. The wood's extractive content and density, combined with the viscosity of the adhesives, resulted in insufficient bonding between the glued pieces. Photomicrographs revealed the presence of tyloses in the wood vessels, which likely contributed to the low percentage of wood failure, placing it below the minimum recommended value (60%) according to normative standards. It was concluded that the use of A. peregrina wood resulted in low-quality bonded joints, due to intrinsic material factors that hindered adhesive bonding.