Production of epoxidized cardanol–based vinyl ester resins with cinnamic acid for eco-friendly coating materials

Environmental concerns about coating material have led manufacturers towards considering bio-based alternatives to conventional petroleum–derived epoxy resins. Considering these concerns with rise in prices and high depletion of petroleum resources, a viable alternative polymer resin has been synthesized from characteristic cashew nut shell liquid (CNSL). In this study, cardanol, a major component of cashew nut shell liquid, was used to synthesize cardanol-based vinyl ester resole (CBVER) and cardanol-based vinyl ester novolac (CBVEN) resins. The vinyl ester resins synthesized were characterized using international standard methods. The molecular weight of the resins was determined to be 1069 and 1001 g/mol for CBVER and CBVEN, respectively, using gas chromatographic mass spectroscopy (GCMS). Fourier transform infrared (FTIR) and thermogravimetric (TGA) analysis were used to identify the functional groups and analyze the material weight changes with stability relative to temperature. FTIR results revealed functional groups typical of thermosetting resin. The results of the mechanical and thermal properties of the resins showed improved performance and material’s thermal stability (up to a temperature of 280 °C), respectively. The chemical resistance properties of the cardanol-based vinyl ester resins showed improved performance when subjected to solvent, alkalis, and acids, an indication of anti-corrosive properties. The better performances of cardanol-based vinyl ester resins obtained from this study is justifiable and suggest applicability in coatings, for both anticorrosion and interior/exterior decorations.