Evaluation of Shear Strength and Wood Failure of Two African Mahogany Species Planted in Brazil

Abstract Interest in the wood industry of African mahogany (Khaya spp.) has increased in Brazil because of the quality of the wood and the similarity to the highly demanded Brazilian mahogany (Swietenia macrophylla King). The objective was to study the shear strength and wood failure of joints of 19-year-old plantation African mahogany species (K. ivorensis and K. senegalensis) bonded with four different commercially used adhesives in order to better evaluate the potential use of this material as a suitable replacement for Brazilian mahogany wood. The resins used in this study were urea-formaldehyde (UF), melamine-urea-formaldehyde (MUF), and emulsion polymeric isocyanate (EPI), and cross-linking polyvinyl acetate (PVAc) was used as a thermoplastic adhesive. PVAc yielded statistically higher shear strength for both species. For K. ivorensis, MUF, EPI, and PVAc reached the minimum value for shear strength as specified by ASTM International. However, with K. senegalensis, PVAc was the only adhesive to meet the standard. For K. ivorensis, PVAc and MUF resulted in statistically higher wood failure, and MUF, EPI, and PVAc met the required percentage of wood failure. In K. senegalensis, MUF and PVAc met the minimum requirement for wood failure. Based on the classification given by ASTM standards, the adhesives MUF, EPI, and PVAc can be used for nonstructural lumber products for K. ivorensis, and PVAC can be used in both species tested.