Development of chemically modified guar gum adhesives for enhanced wood bonding performance

The development of eco-friendly wood adhesives from biomass polymers is challenging due to their poor water resistance and low wet bonding strength. To overcome these limitations, a modified guar gum (MGG) adhesive was developed via a combined approach of acrylate grafting, epoxy ring-opening, and silane coupling. This chemical modification established a stable cross-linked network, significantly enhancing cohesive and interfacial adhesion. The viscosity of MGG was reduced to about 900 mPa·s, greatly improving coatability compared to raw GG (6000 mPa·s at 1 % concentration). The optimized adhesive showed a dry bonding strength of 1.67 MPa and a wet bonding strength of 0.84 MPa, outperforming many previously reported biomass-based adhesives. Improved thermal stability and moisture resistance were also confirmed, attributed to introduced aldehyde and ether groups that promote dense crosslinking. This work not only demonstrates a viable pathway to overcome the intrinsic weaknesses of GG, but also highlights MGG as a sustainable and high-performance alternative to conventional formaldehyde-based wood adhesives, providing both practical applicability and scientific significance.