Synthesize and Evaluating Barrier Effects of Polyaniline-Clay Nanocomposites as a Barrier Pigment in Zinc Rich Ethylsilicate Primer

This paper presents the works done to synthesize undoped and HCL doped polyaniline/clay nanocomposite (PAniCN) by chemical oxidative polymerization of aniline monomers in the presence of Cloisite 30B nano-clay powders. Scanning electron microscopy (SEM) was used to characterize the morphology and particle size of as-synthesized nanocomposites. FTIR analysis was used for characterizing and comparing the chemical structure of nanocomposites. The nanocomposites were added to a commercial zinc rich ethyl silicate primer to modify its barrier properties. Unmodified and modified primers were applied with the same dry film thickness on the carbon steel panels, separately. The corrosion protection performances of different primers were evaluated via determining open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) during immersing in 3.5% sodium chloride solution for a period of 90 days. Results revealed that although undoped modified primer showed the highest barrier properties, non-conducting nature of this nanocomposite affect onto the cathodic protection properties of modified primer. On the other hand, HCL doped nanocomposite modified primer showed good barrier properties and this conductive nanocomposite did not have negative effect onto the cathodic protection mechanism of the primer.