Epoxy coating based on montmorillonite-polypyrrole: Electrical properties and prospective application on corrosion protection of steel

In this study, nanostructured composite based on Montmorillonite-Polypyrrole (Mt-PPy) was prepared via in situ chemical polymerization of Pyrrole in presence of Mt and dodecyl benzene sulfonic acid (DBSA). Subsequently, the as-prepared Mt-PPy additive as well as pure Mt and PPy were incorporated into an epoxy coating as anticorrosive protection additives for low carbon steel. The electrical conductivity, chemical changes and microstructure of the as-prepared electrically conductive additives were investigated. Steel coated specimens were prepared via solvent cast method and the anticorrosion protection ability of the coatings was evaluated by means of electrochemical impedance spectroscopy (EIS). Likewise, surface features of the coatings such as contact angle and roughness were examined. Due to the higher aspect ratio and ease of dispersion of Mt-PPy epoxy coatings loaded with Mt-PPy additives exhibited higher electrical conductivity values with respect to those containing merely PPy. Besides, contact angle (CA) between deionized water and Epoxy/Mt-PPy coated carbon steel was higher than CA for neat epoxy whereas CA of Epoxy/PPy and Epoxy/Mt were significantly reduced. EIS measurements revealed higher impedance values for Epoxy/Mt-PPy coating; the outputs of EIS suggested enhanced barrier property of epoxy coating when Mt-PPy additive was added. The results observed in this study are pointing towards the prospective use of the Epoxy/Mt-PPy with 5 wt% content as a corrosion protective coating for carbon steel.