Preparation and properties of few‐layer graphene modified waterborne epoxy coatings

Abstract

ABSTRACTFew layer graphene (FLG) has been used to improve different properties of polymers. FLG‐modified waterborne epoxy dispersions were prepared using a hydrophilic epoxy oligomer (HEO‐144) as the surfactant, which was prepared using liquid epoxy resin and poly(ethylene glycol) (PEG4000) at a molar ratio of 1.0. To enhance the stability of FLG‐modified waterborne epoxy dispersions, fumed silica was added and best stability was reached at a fumed silica content of 1.5%. Thermogravimetric analyses demonstrated enhanced thermal stability of the epoxy films after FLG modification. With FLG content of 1.0%, T5% of the modified epoxy films has been increased to 332 °C from 275 °C. Water contact angle and adsorption tests showed improved water resistance with FLG, the water contact angle increased from 49.5° to 76.2° and water adsorption decreased from 9.0% to 2.0%. Furthermore, electrochemical impedance spectroscopy tests and tafel analysis indicated that FLG greatly improved the anticorrosion performance of waterborne epoxy coatings. With a FLG content of 1.0%, modified waterborne epoxy coatings demonstrated significantly low corrosion rate, which was one eighth of that of the unmodified control. These results indicate that FLG modification can be an effective and low cost approach to enhance the anticorrosion performance of waterborne epoxy coatings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46743.