Graft copolymerization for developing high-adhesion starch-based wood adhesives for environmentally friendly plywood

Cost-effective and sustainable biomass-based materials are being explored as alternatives to formaldehyde-based adhesives. However, the direct application of pure biomass materials for bonding purposes does not yield satisfactory results. Graft copolymerization is a widely recognized method for chemical modification. In this study, a novel formaldehyde-free wood adhesive was synthesized through graft copolymerization using N -methylolacrylamide (NMA) and cassava starch (CS). The physical and chemical properties, reaction mechanisms, and bonding mechanisms of the adhesive were thoroughly investigated. Characterization techniques such as FTIR, NMR, XPS, and SEM confirmed significant improvements in the properties of the graft copolymer adhesive, attributed to increased crosslinking density and the formation of highly interconnected structures. The cured adhesive demonstrated exceptional plywood bonding performance and water resistance, with shear strengths of 1.31 MPa (dry strength), 1.01 MPa (cold water strength), and 0.91 MPa (hot water strength), representing a substantial improvement over pure CS adhesive. This straightforward and economically viable strategy offers a promising avenue for developing biomass formaldehyde-free adhesives and promoting advancements in the wood industry.