Synthesis, characterization, antibacterial and corrosion protective properties of epoxies, epoxy-polyols and epoxy-polyurethane coatings from linseed and Pongamia glabra seed oils

The aim of this paper is to investigate the structures and properties of epoxidized linseed and Pongamia glabra oils (LOE/POE), their derived products—epoxy-polyols (HLOE/HPOE), epoxy-polyurethanes (EU = LOPU/POPU) and EU coatings. Changes in epoxy equivalent, iodine value, hydroxyl value and percent saturation of oil backbone in due course of epoxidation and hydroxylation reactions, were plotted as a function of time. Spectral (IR, 1H NMR and 13C NMR), physico-chemical and thermal (TGA and DSC) analyses of aforementioned resins were performed by standard methods. Physico-mechanical and chemical resistance tests reveal that coatings of LOPUs perform better than those of POPUs. It was found that properties of oil epoxy-polyurethane coatings are mainly governed by: (i) fatty acid composition and nature of starting oils, (ii) extent of epoxidation, (iii) number and location of hydroxyls and residual double bonds in the final product and (iv) the presence of long dangling chains. PO, HLOE and LOPUs exhibit good antibacterial activity against Escherichia coli at very small MIC. These EU systems can be safely employed unto 220 °C.