Eugenol/vanillin-derived novel triarylmethane-based crosslinking agent for epoxy coating

The current research work focuses on the synthesis of a novel crosslinking agent for epoxy coating using bio-based materials: eugenol and vanillin. The synthesis was carried out using the method used for the production of triarylmethane-based compounds. The structure of the final product, vanillin/eugenol curing agent (VECA), was confirmed using hydroxyl value, FTIR and H-1 NMR. The significant improvement in the thermal properties of the epoxy cured films was investigated with the incorporation of this compound in various proportions. The char yield and the glass transition temperature were at their maximum for the film with the total replacement of the commercial hardener by the synthesized compound. The mechanical properties of the coated mild steel panels were checked using impact test, cross-cut adhesion, flexibility and pencil hardness which showed similar results for all the formulations except for a 100% loading of the material as the film was brittle. The solvent resistance of the epoxy coatings retained even after loading of VECA. The gel content values were high for VECA formulations due to increased crosslinking which led to lower water absorption values. The color of the coating films was checked using colorimeter which showed that VECA100 had the darkest color.