Study on the effect of ultrasonication time on transport properties of polyurethane/organoclay nanocomposite coatings

In this study, a series of polyurethane (PU)/organically modified montmorillonite (OMMT) clay nanocomposites were synthesized by in situ polymerization technique through an ultrasonication-assisted process at various processing times. Wide angle X-ray diffraction (WAXD) was employed to investigate the effect of processing time on degree of delamination of clay platelets. In order to evaluate the effect of ultrasonication time on transport properties of the PU/OMMT composites, diffusion coefficient and maximum water uptake were determined through a water permeation test. Electrochemical impedance spectroscopy (EIS) was carried out to analyze the barrier properties and to evaluate the corrosion performance of these composite coatings on carbon steel panels. It was found that by increasing sonication time, the barrier property of nanocomposites against diffusion of water molecules was improved. This is due to further separation of clay platelets and enhancement of the traveling pathways for water molecules.