Improved dispersion of the graphene and corrosion resistance of waterborne epoxy-graphene composites by minor cellulose nanowhiskers

The uniform dispersion of graphene (GN) in a polymer matrix is still challenging at high loadings. In this study, we introduced a tiny number of cellulose nanowhiskers (CNWs; CNWs/GN = 1:20 w/w) to improve the dispersion of GN nanoplatelets in a waterborne epoxy (WEP) matrix at a GN loading of 1.0 wt %. Compared with that of 1.0% GN-WEP, the Young's modulus of the 1.0% GN-WEP-CNWs was enhanced by about 20.5%. The glass-transition temperature increased from 70.4 degrees C for 1.0% GN-WEP to 72.8 degrees C for 1.0% GN-WEP-CNWs. The water contact angle of composite film increased by 17 degrees, from about 79 degrees for the film without CNWs to about 96 degrees for the film with CNWs. The anticorrosion efficiency of the coatings was also evaluated with the potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The results reveal the CNW-containing coating showed better corrosion resistance for mild steel and could be applied as a green dispersant for GN in WEP coatings. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47631.