Investigation of the effects of electrochemically synthesized poly pyrrole (PPy), poly n-metil pyrrole (PmPy) and PPy/PmPy on corrosion behaviours of iron based materials

The essential drawback for the use of conducting polymers for anticorrosive purposes is water up taking through the porous structure and resulting low durability in corrosive environment. In this study, it was aimed to prepare less permeable, highly stable polymer films with copolymerization of pyrrole and N-methyl pyrrole from aqueous oxalic acid solution. Mild and stainless steel substrates were coated with PPy, PmPy and copolymer films. Then the samples were examined in 3,5% NaCl and 0,1 M HCl solutions by means of potentiodynamic measurements, linear polarization resistance and electrochemical impedance spectroscopy. The activation energy, Gibbs free energy changes and entropy changes were determined with interpretation of the effect of temperature. The copolymer[1:3] film showed the best result which was also supported with theoretical calculation for corrosion resistance.