Blends of Epoxidized Alkyd Resins Based on Jatropha Oil and the Epoxidized Oil Cured with Aqueous Citric Acid Solution: A Green Technology Approach

Alkyd resins with 100% phthalic anhydride were prepared from jatropha oil by two-stage alcoholysis-polyesterification reactions. To improve the performance characteristics, resins were blended with different wt % of epoxidized jatropha oil (EJO) and aqueous citric acid solution without the addition of any other catalyst or solvent. Blending was facilitated via epoxidation of the alkyd resins. The prepared blends were characterized by Fourier transform infrared and NMR (H-1 and C-13) spectroscopy studies. It was observed that the properties like curing time, chemical resistance, scratch hardness, thermal stability, and tensile strength of the alkyd resins improved significantly on blending. With 50 wt % EJO content, the thermal stability and tensile strength of the blends increased by 42 degrees C and 3.18 MPa, respectively. The results indicate the strong influence of the amount of EJO and citric acid on the performance of the alkyd resins. The thermal and mechanical properties of the cured films can be further improved by postcured at 160 degrees C. Scanning electron microscopy study showed the uniform surface morphology of the blends. Overall, the results of this study suggest suitability of these blends in surface coating applications