Compatibility of preservative with adhesive in Eucalyptus grandis laminates

The fundamental factors responsible for the complexities in adhesive bonding of preservative-treated wood are predominantly wood species, preservative composition, and adhesive system. It is post-effect of these factors that process variables such as assembly times and bonding pressure exert secondary influences on adhesive-bond development in preservative-treated laminates. Hence, this study investigated the effect of copper azole (CA) and disodium octaborate tetrahydrate (DOT) impregnations on E. grandis heartwood (HW) and sapwood (SW) bonding with melamine-urea-formaldehyde and polyurethane adhesives. Based on the adhesives and bonding conditions investigated, the CA and DOT-treated E. grandis laminates do not satisfy at least one of the shear strength and delamination requirements according to EN 14080:2013. Contrary to delamination, shear strength was significantly affected by the HW-SW difference. This study established the basis for further considerations on adapting bonding conditions for improved adhesive-bond performance in CA and DOT-treated E. grandis laminates towards manufacturing durable hardwood composite for tropical and subtropical environments.