Investigating the characteristics of cactus seeds by-product and their use as a new filler in phenol formaldehyde wood adhesive

The current study investigates the properties of cactus waste seeds (CWS) unexplored by-product as partial replacement of phenol formaldehyde (PF) adhesives in comparison to previously used olive stones (OS) for the production of wood composites. The chemical composition, structure, and thermal properties of CWS were studied for the first time to evaluate their suitability for incorporation into PF resins. The bonding strength, wood failure, and rheological properties of the formulated adhesives were investigated as well as the mechanical properties of the plywoods panels. The results showed that CWS could be considered as a new lignocellulosic resource, showing a higher amount of cellulose content (27%) compared to OS (15%). The crystallinity and thermal stability were higher in CWS, which was expected to improve the performance of the formulated adhesives positively. Moreover, the resins containing 10% and 15% of CWS and OS, respectively, showed comparable bonding strength and wood failure to that of a control PF resin. While plywood bonded with 10% of CWS:PF resin showed better mechanical performance in dry, cold, and 8h boiling water conditions than other adhesives, formaldehyde emission levels of bonded panels with both formulations were lower than those of a control PF.