Self-healing polymer coating with the microfibers of superabsorbent polymers provides corrosion inhibition in carbon steel

Abstract

In the present study, multi-layer polymer coatings composed of the microfibers of a superabsorbent polymer (SAP) were applied to carbon steel to promote corrosion inhibition. The SAP microfibers were fabricated by mixing SAP powder with water, which created a film that could then be coated onto a glass plate where it was allowed to dry and was then cut with a knife-edge using a 3-axis desktop robot. Water/polymer ratios between 20 and 60 produced SAP microfibers 30 to 50μm in diameter. The prepared SAP microfibers were mixed with vinyl-ester polymer (VEP), and were then coated onto a substrate. Specimens were scratched with a knife-edge, and then polarization resistance in a 0.5wt% NaCl solution was measured. A coating with VEP as the base and top layers and 5wt% SAP microfibers as the middle layer showed polarization resistance that increased with testing time and demonstrated self-healing corrosion inhibition. A thin corrosion protective film formed on the scratched surface of the specimen coated with SAP microfibers. Measurement of the polarization curves at various testing times confirmed that the SAP film had corrosion protective qualities that prevented cathodic and anodic reactions. Fiberization of the SAP resulted in large releases of SAP from the coating that continued for an extended period of time.