A walnut meal-based wood adhesive with enhanced water resistance and mildew stability through organic-inorganic hybrid interactions

A walnut meal-based adhesive was developed via organic-inorganic hybridization. • The adhesive achieved 1.14 MPa wet strength after 63 °C water treatment. • Multiple interactions enhanced cohesion, thermal stability, and durability. The development of bio-based wood adhesive is considered an effective strategy to reduce formaldehyde emissions and their adverse impacts on the environment and human health. In this work, inspired by the organic–inorganic synergistic architecture of natural biomineralized structures, walnut meal (WM) based adhesive with excellent property was developed in the laboratory by introducing 3-aminopropyltriethoxysilane (APTES) modified SiO 2 as a reinforcing phase and glycerol triglycidyl ether (GTE) as covalent crosslinker. Comprehensive characterization, including dry/wet bonding strength, thermal stability, water resistance, and mildew resistance tests, demonstrated that the optimal dry bonding strength of plywood produced with WM-based adhesive was 1.76 MPa and 1.14 MPa wet bonding strength after immersion in water at 63 °C for 3 h. Meanwhile, the mass retention of the cured adhesive could reach 85.65% after being treated under the same conditions. Moreover, the cured adhesive exhibited excellent thermal stability and mildew resistance, with a char residue of 40.87% at 600 °C and no obvious mildew growth after 24 days of storage. This biomimetic strategy provides a new approach for the high-value utilization of walnut meal and the development of green, formaldehyde-free wood adhesives. Download: Download high-res image (190KB) Download: Download full-size image