Development of sustainable resource based poly(urethane-etheramide)/Fe2O3 nanocomposite as anticorrosive coating materials

Linseed polyetheramide (LPEtA) resin was synthesized by the condensation polymerization of N-N-bis (2-hydroxyethyl) linseed oil fatty amide (HELA) with pyrogallol. The residual hydroxyl groups of LPEtA resin were further modified with isophorone diisocyanate (IPDI) to obtain linseed poly(urethane-etheramide) (ULPEtA) via addition polymerization. ULPEtA was modified with iron oxide nanoparticles in different weight percent (0.1 wt%, 0.2 wt%, 0.3 wt% and 0.4 wt%) producing ULPEtA/Fe2O3 nanocomposite. Spectroscopic characterization of HELA, LPEtA and ULPEtA was carried out by using Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (H-1-NMR) and carbon nuclear magnetic resonance (C-13-NMR) techniques. Physicochemical and physico-mechanical properties of LPEtA and ULPEtA were carried out by using standard methods. Thermal stability and anticorrosion performance were assessed by thermogravimetric analysis/differential scanning calorimetry (TGA/DSC) and potentiodynamic polarization. The corrosion behavior of ULPEtA/Fe2O3 nanocomposite coatings on mild steel was investigated in different corrosive environments (3.5 wt% HCl, 5.0 wt% NaCl, 3.5 wt% NaOH, and tap water) at room temperature. Surface morphology study was performed through scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). Coating properties such as gloss, scratch hardness, flexibility and impact resistance were evaluated using standard methods. The results of this study showed that ULPEtA/Fe2O3 nanocomposite coatings exhibit good physico-mechanical, anticorrosive properties and can be safely used up to 220 degrees C.