Corrosion resistance of polyvinyl butyral coatings enhanced by montmorillonite-chitosan composites

To improve the corrosion resistance of 304SS, a polyvinyl butyral/organic montmorillonite-chitosan (PVB/OMMT-Ch) composite coating was prepared by the spin coating method. The Montmorillonite was organically modified with Cetyltrimethylammonium Bromide and compounded with Chitosan to obtain OMMT-Ch. OMMT-Ch filler has been introduced into the polyvinyl butyral coating to improve the corrosion resistance of 304 stainless steel. Scanning electron microscope and transmission electron microscope observations showed that the introduction of chitosan made the montmorillonite layers rounded and loose, and the X-ray diffraction (XRD) results indicated that the interlayer spacing between the montmorillonite layers changed significantly, and the FT-IR results of the chitosan/montmorillonite insertion complexes were in good agreement with those of the XRD analyses, which showed that chitosan successfully inserted between the layers of montmorillonite. The corrosion resistance of the composite coatings in 3.5% NaCl solution was tested by Tafel polarization curves and electrochemical impedance spectroscopy. The results showed that the composite coatings doped with 0.5% OMMT-Ch had the best corrosion resistance with long-lasting protection of more than 160 days. This study suggests a novel approach for nanocomposites for dealing with the 304SS corrosion issue.