Morphological and Water Absorption Properties of Encapsulated Epoxy/Cellulose Nanofibrils/Nanoclay Coatings for Water Barrier and Anticorrosion Applications

Abstract

The effect of water absorption properties of encapsulated nanoclay and cellulose nanofibrils on epoxy coating for barrier and anticorrosion applications was investigated. Epoxy-based nanocomposite coatings were fabricated using solution blending, with cellulose nanofibrils and nanoclay as nano-reinforcements. The nanofillers were encapsulated using the interfacial polymerization method. In this method, a polymerization reaction occurs at the interface of two immiscible phases, usually an oil phase and a water phase, to create polymeric capsules. The impact of encapsulated nanofillers on the nanocomposite coatings' water absorption and corrosion properties was investigated. The chemical constituents and nanostructure of the nanomaterials were characterized using Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). The encapsulated nanofillers were incorporated into the epoxy-based coating and applied to steel substrates. The anticorrosion performances of the epoxy-based nanocomposite coatings were investigated through water absorption and immersion tests in NaCl solution. The TEM results demonstrate that a nanoclay of a 7 – 15 nm diameter was obtained. The water absorption study revealed that epoxy/CNF absorbed more water than epoxy/nanoclay. The sample containing 5 wt% clay and 2.5% CNF has the lowest water absorption. The water immersion test demonstrates that the plain epoxy coating, followed by the epoxy/CNF-coated metal, has greater water absorption and exhibits greater corrosion under visual inspection. The results demonstrate that the water absorption properties of epoxy-based coating can be improved by incorporating nanofillers.