Study of dextrin-derived curing agent for waterborne epoxy adhesive

In this study, a water-soluble dextrin derivative was synthesized by reacting dextrin with trimellitic anhydride. The chemical structure of the dextrin-derived curing agent was confirmed by FT-IR and 1H NMR. The dextrin derivative contained free carboxylic acid groups and was used as curing agent for waterborne epoxy in wood bonding test. The adhesion of wood bonded by this waterborne epoxy system was studied and compared with that of wood bonded by phenol–formaldehyde resin. Results showed that the two adhesive systems displayed very similar block shear strengths and specimen failures. The two types of adhesives also showed similar extents of resin penetration into the wood substrate. This study demonstrated that starch or dextrin could be used as an economic feedstock for synthesis of curing agents for waterborne epoxies in the effort to develop formaldehyde free and volatile organic compounds (VOC)-free wood adhesives.