Exploring in situ integration of pongamia oil to improve barrier properties of polyurethane coatings

Abstract

Polyurethane coatings have been the focus of continuous innovation, such as bio‐based coatings and self‐healing coatings. This study investigates the route achieving superior coatings by in situ integration of pongamia oil during the curing process. Stronger urethane and carbonyl bonds for these oil‐modified coatings are observed using Fourier transform infra‐red spectroscopy. Thermogravimetric analysis reveals an increase in their thermal stability. A sustained high coating resistance and an increased Bode impedance (by ∼102 Ω cm2) for the oil‐modified coatings is observed using electrochemical impedance spectroscopy, which is corroborated by the cyclic corrosion test. Scanning electron microscopy depicts a roughened coating morphology with an increased water contact angle due to the integrated oil‐polyurethane polymer chains. Further, a preliminary computational fluid dynamics confirms this inhibited electrolyte mass flow through an oil‐modified coating with denser regions as compared to a clear coating. A consolidated schematic model incorporating the experimental and simulation results is proposed.

Effects of Curing Temperature and Silica Content on the Structure and Properties of a Sol–Gel PU-Silica Hybrid Coating for Corrosion Protection

“…The high capacitive behaviors of the coatings, except for 0.5SPU150C, were consistent with the phase angles close to −90°. These protective barrier properties were superior to those of several PU coatings reported in the literature, which presented average | Z 5 | in the region of 10 8 Ω cm 2 for analyses at times between 14 and 30 days. − In contrast, the impedance decrease for the 0.5SPU150C sample was similar to the decreases reported previously during aging. ,, This poor behavior could be attributed to the structural arrangement of the organic and inorganic parts (unhydrolyzed ethoxy groups and less dense aggregates), which facilitated access of the electrolytes to the coating/metal interface. The lower but constant | Z 5 | for the 0.5SPU183C sample could be attributed to an electrolyte path facilitated only by the PU structure, since the inorganic part presented more condensed and denser aggregates, compared to the 0.5SPU150C sample.…”

Recent Trends in Waterborne and Bio‐Based Polyurethane Coatings for Corrosion Protection

“…Ranade et al, indeed, investigated the effectiveness of pongamia oil as corrosion inhibitor for steel. [59] To improve the anticorrosion performances of neem oil-based PU coatings, Gite and co-workers added microcapsules containing linseed oil as a healing agent, which can be released when damages [13] Copyright 2017, Wiley-VCH.…”

Nonedible Vegetable Oil-Based Polyols in Anticorrosive and Antimicrobial Polyurethane Coatings

“…A review of various PUs elucidated the influence of the crosslinking on the properties of the PUs due to the formation of the three-dimensional network. The crosslinked structure reduces the void space, pores, and free volume in the coating structure, making the path for the penetration of the corrosive electrolyte more tortuous [ 123 ]. Ahmad et al delivered a pioneering work on PU coatings prepared from LO by epoxidation and hydroxylation, showing good anticorrosive properties due to their highly crosslinked structure [ 105 ].…”

“…Gite et al compared the anticorrosive properties of NO-based alkyd-modified PU coatings by using an immersion method, exhibiting better anticorrosive nature due to increased crosslinking reaction [ 121 ]. Ranade et al explored the integration of PO for better crosslinking of PU coating, inhibiting electrolyte mass flow through the coating [ 123 ]. Gite et al showed that the combination of CO monoglycerides and IPDI trimer forms better crosslinked PUs, exhibiting good resistance towards acids, alkalis and solvents [ 129 ].…”