Corrosion protection of mild steel by environment friendly Polypyrrole/Gum Acacia Composite Coatings

¹Department of Chemistry, Maitreyi College, University of Delhi, New Delhi 110021, India

²Polymeric & Soft Materials Section, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi 110012, India

Adv. Mater. Lett., 2018, 9 (3), pp 158-168

DOI: 10.5185/amlett.2018.7007

Publication Date (Web): May 16, 2018

Copyright © IAAM-VBRI Press

E-mail: skdhawan@mail.nplindia.org

Abstract

In a novel approach, Polypyrrole/Gum Acacia composites (PPy/GA) were synthesized by in-situ oxidative polymerization of pyrrole on the Gum Acacia (GA) surface by using FeCl₃ as oxidant. The ¹HNMR and FTIR confirms the presence of peaks of Polyprrole and Gum Acacia in the composite. The microstructural analysis of the composite reveals uniform layer of Polypyrrole on the surface of GA particles. The X-ray Diffraction pattern reveals the amorphous nature of the composite. Powder coating technique was used to design the composite coatings. The electrochemical studies like Open Circuit Potential (OCP) variation with time, Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS) were conducted in 3.5% NaCl solution to evaluate the corrosion resistance of the coatings. The composite coatings demonstrated superior corrosion resistance in salt spray fog of 5.0% NaCl (under accelerated test conditions in salt spray chamber). The synergistic combination of the corrosion inhibition properties of Gum Acacia and the redox properties of Polypyrrole is the reason for the occurrence of high corrosion resistance of the composite coatings. The present coating composition has shown excellent corrosion resistance and can be a potential coating formulation for mild steel substrate used in various applications under saline conditions.

Keywords

Gum acacia, polypyrrole, EIS, potentiodynamic polarization.