Tannic Acid‐Ethanolamine Modified <scp>LDPE</scp> Films for the Fabrication of Interfacially Reinforced Thermoplastic Resin‐Bonded Plywood

ABSTRACT In recent years, the plywood industry has been shifting toward formaldehyde‐free alternatives, with the replacement of traditional aldehyde‐containing adhesives by eco‐friendly formaldehyde‐free adhesives becoming a key research focus in plywood manufacturing. Polyethylene (PE) has been used as a viable bonding agent for plywood. However, the significant polarity difference between PE and wood leads to low interfacial compatibility, impairing the bonding strength of thermoplastic resin‐bonded plywood. Thus, developing simplified surface treatment techniques for thermoplastic resins to enhance resin‐wood compatibility is critical. In this study, tannic acid (TA) and ethanolamine (EA) self‐polymerize on low‐density polyethylene (LDPE) film surfaces to form an adhesive layer and increase the surface polarity and hydrophilicity of LDPE film. Using the TA‐EA modified LDPE film as the adhesive layer, formaldehyde‐free thermoplastic resin‐bonded plywood is prepared. The results show that the interfacial bonding between LDPE film and wood is effectively improved, and the mechanical properties and water resistance of the plywood are significantly enhanced. The study further investigates the effect of TA‐EA modification on the bonding strength of PE‐bonded plywood and its strengthening mechanism through microstructure analysis, chemical structure characterization, potentiometric analysis, and thermodynamic analysis. The research provides a performance enhancement strategy for the preparation of formaldehyde‐free, eco‐friendly thermoplastic resin‐bonded plywood.