Functionalized Natural Tannins For Preparation of a novel non-isocyanate polyurea-based adhesive

In recent years, the shortcomings of products bonded with adhesives of conventional resins (e.g. urea-formaldehyde, phenol-formaldehyde, melamine-based) have raised concerns as people have become more environmentally conscious while fossil resources are in short supply. This has prompted researchers to develop a new generation of adhesives derived from natural renewable biomass resources, with excellent properties and no or limited contamination. In this study, a novel epoxidized tannin-based non-isocyanate polyurea adhesive was prepared from natural tannin after functionalization with epichlorhydrin. The structure, molecular weight, and thermal degradation behavior of this resin adhesive synthesized in this way, were investigated using FT-IR, ESI-MS, GPC, and TGA, respectively. The mechanical properties and water resistance of the produced plywood were evaluated. It was found that the adhesive possess ideal bonding strength and excellent water resistance, and the prepared plywood can have potential application prospects under harsh conditions.