Utilization of extract of fresh tree leaves as extender in synthetic adhesives for laminated veneer lumber (LVL)

► Yield of extraction of ash and cedrus leaves was used as bonding agent in adhesives. ► Urea-formaldehyde (UF) and polyvinylacetate (PVAc) adhesives were used. ► Extract of leaves improved bond performance of the UF bonded laminated veneer lumber. ► Extract of ash leaves had better bonding performance than that of cedar leaves. ► Extract of leaves was more compatible with the UF adhesive than the PVAc adhesive.