Effect of incorporation of surface treated zinc oxide on non-isocyanate polyurethane based nano-composite coatings

Non-isocyanate polyurethanes (NIPUs) based on cyclic carbonate-amine chemistry are an emerging area for polymer synthesis and is being extensively studied for various applications. A successful utilization of this technology can eliminate many of the issues associated with conventional polyurethane chemistry. While these polymers have not yet achieved commercial significance, research is being devoted to methods for synthesizing polymers or oligomers containing cyclic carbonate groups as well as studying their applications in thermoplastic and thermosetting systems. Nevertheless, NIPU based coating systems are still unexplored for corrosion protection of metals. In the current study, zinc oxide (ZnO) particles prepared via in situ method were treated with cyclic carbonate functional alkoxy silane. The surface treatment of ZnO particles was confirmed by particle size analysis, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDAX) and X-Ray Diffraction Spectroscopy (XRD). NIPU formulations with variable proportion of treated and untreated ZnO particles were prepared using cyclic carbonate modified epoxy resin and coated on mild steel substrates. The nano-composite coatings prepared thereof were evaluated for their mechanical and chemical performance. The anticorrosive performance was evaluated by salt spray test and electrochemical impedance spectroscopy (EIS). The study conducted showed significant enhancement in scratch hardness and abrasion resistance along with improvement in other performance properties after addition of treated ZnO particles in nano-composite coating formulations. (C) 2013 Elsevier B.V. All rights reserved.