Alkyd resins are considered modified polyester resins, which may be modified with many chemicals such as polybasic acids, polyhydric alcohols and/or fatty acids to produce resins with different properties and give the final surface coating formulations wide performance range. In this research, the soya bean based N,N-bis(2-hydroxyethyl)thiophene-2-carboxamide (HETCA)-modified alkyd resins and N,N-bis(2-hydroxyethyl)furan-2-carboxamide (HEFCA)-modified alkyd resins are prepared by partial replacement of glycerol (G) with each (HETCA) (I) and (HEFCA) (III), respectively, which are reacted as source of polyhydric alcohols, with both phthalic anhydride (PA) and soya bean oil fatty acids (SOFA), as source of polyacids .
The new HETCA-modified alkyd resins and previously prepared HEFCA-modified alkyd resins enter in final coating formulations and their performance are evaluated and compared using the international standard test methods (ASTM) and involved the measurement of phyisco-mechanical properties such as viscosity, drying time, specular gloss, pencil hardness, adhesion, flexibility. In general, the results show that the modification enhances both phyisco-mechanical and chemical properties. The corrosion resistance of alkyd resins improved by such HETCA and HEFCA- modification
Additionally, expected corrosion inhibitors such as morpholino(thiophen-2-yl)methanone (II) and morpholino(furan-2-yl)methanone (IV) are prepared and their anticorrosion effect is investigated by two ways. First, as an additive with unmodified (commercial) alkyd resin in zinc phosphate primer formulations. Second, as an additive with previously prepared HETCA- and HEFCA-modified alkyd resins in the same primer formulations. Both of corrosion inhibitors (II) and (IV) improve the corrosion resistance at certain dosages.