Anti-corrosion properties of Polyaniline/Polyurethane composite coatings on mild steel using cocopol blend polyols
Marjune T. Bonilla (a,b)*, Archie G. Ruda (a,b), Dave Joseph E. Estrada (c), Kurt Sterling M. Ubas (a,b), Aaron Andrew B. Mutia (a,b), Lloyd Allan T. Cabanog (a,b), Arnold A. Lubguban (c), Rey Y. Capangpangan (d), Joselito P. Labis (e), and Arnold C. Alguno (a,b)

a Department of Physics, MSU- Iligan Institute of Technology, Tibanga, Iligan City, 9200, Philippines
b Premier Research of Science and Mathematics (PRISM), MSU - IIT, 9200 Iligan City, Philippines
c Bio-products research laboratory, MSU-IIT, Iligan City, Lanao Del Norte, 9200, Philippines
d Department of Physical Sciences and Mathematics, MSU-Naawan, Misamis Oriental, 9023, Philippines
e King Abdullah Institute for Nanotechnology, King Saud University, 11451 Riyadh, Saudi Arabia

Abstract

Polyurethane coating has been widely used as a protective coating due to its wide range of mechanical strength, excellent abrasion resistance, toughness, low-temperature flexibility, and chemical resistance, simplicity in production and application, and superior protection on corrosion to mild steel. No studies have reported utilizing cocopol blend polyols to produce polyurethane-based protective coatings on mild steel. In this work, we fabricated polyurethane-based and PANI/PU composite coatings with varying amounts of polyaniline nanoparticles on mild steel using cocopol blend polyols (combination of coconut-based polyol and polypropylene glycol) exposed in 3.5 wt% NaCl aqueous solution for anti-corrosion application. Characterizations like Fourier Transform Infrared Spectroscopy (FTIR), Potentiodynamic Polarization (Tafel plot), contact angle, adhesion test, FESEM, XRD, and UV-VIS were used in this study. Tafel plot revealed that PU-based and PANI/PU composite coatings exhibited a significant reduction in corrosion current density (Icorr), perhaps due to the inhibitor present in the coating, which reduced the corrosion rate of the metal by retarding the anodic process. Among all fabricated coatings, 0.5-PANI/PU composite coating was the best, having a less corrosion rate of 5.66x10-5 mmpy compared to others. In addition, its surface was more compact, smooth, and rigid, according to the result of FESEM, suggesting that it has better corrosion protection to mild steel. Hence, PU-based protective coating and PANI/PU composite coatings using cocopol blend polyols inhibited the penetration of the corrosive species and served as adequate barrier protection to corrosion for mild steel.

Keywords: Polyurethane-based protective coating, cocopol blend polyols, Polyaniline/Polyurethane composite coatings, Potentiodynamic polarization (tafel plot), contact angle, adhesion test, FESEM, anti-corrosion coating

Topic: Material and Applied Chemistry