Valorization of Mopa Mopa Resin as a Renewable Bio-Based Adhesion Promoter for Sustainable Wood Adhesives

Abstract

The search for renewable raw materials for developing wood adhesives has driven the study of natural resins with intrinsic adhesive properties. This work evaluated Mopa Mopa resin (Elaeagia pastoensis Mora) as an adhesion promoter in formulations for wood-to-wood bonding of pine. Initially, the individual behavior of the main components was assessed, and subsequently, nine systems were formulated by combining Mopa Mopa resin with polyvinyl acetate (PVAc), polyvinyl alcohol (PVA-OH), and starch. The selected formulations were compared with two commercial adhesives using shear and direct tensile strength tests, physical properties, FTIR, TGA, DSC, and fracture surface analysis. Mopa Mopa resin, evaluated individually, achieved a shear strength of 6.657 MPa, second only to that obtained with PVAc among the components studied. Following the initial screening stage, formulations F-3 and F-5 were selected and subsequently prepared as final adhesive systems containing 5.8% additives. Final formulation F-3 consisted of 54.2% PVAc, 20% Mopa Mopa resin, 20% PVA-OH, and 5.8% additives, whereas F-5 consisted of 29.5% PVAc, 37.5% Mopa Mopa resin, 27.2% cassava starch, and 5.8% additives. F-3 achieved a shear strength of 7.792 MPa, surpassing the commercial adhesive C1 (6.328 MPa), while F-5 achieved the highest average direct tensile strength (1.371 MPa). Physicochemical characterization confirmed the presence of functional groups associated with the formulation components, while fracture analysis of F-3 revealed cohesive, mixed, and substrate failures. Taken together, the results demonstrate the potential of Mopa Mopa resin as a functional component and adhesion promoter in wood formulations, allowing its combination with synthetic polymers and renewable raw materials to obtain bonds with competitive mechanical performance.