Comparative Study of the Corrosion Inhibition Efficacy of Polypropylene Glycol and Poly (Methacrylic Acid) for Mild Steel in Acid Solution

The performance of polypropylene glycol (PPG) and poly (methacrylic acid) (PMAA) as corrosion inhibitors for mild steel in acid solution was assessed by weight loss, electrochemical (electrochemical impedance spectroscopy, linear polarization resistance and potentiodynamic polarization), and surface analysis (water contact angles) techniques. Results obtained showed that both polymers inhibited mild steel corrosion but PPG was the best inhibitor. Inhibition efficiency increased with the increase in inhibitor concentration but decreased with temperature rise. Polarization results show that both PPG and PMAA behaved as a mixed-type inhibitors. The adsorption of the polymers onto the mild steel surface followed Temkin adsorption isotherm model. The variation of inhibition efficiency with temperature point toward physical adsorption which is supported by the kinetic and thermodynamic parameters derived from the experimental data. Water contact angle measurement results show that the polymers were adsorbed onto the mild steel surface.