The effect of functional graphene oxide nanoparticles on corrosion resistance of waterborne polyurethane

Abstract For waterborne coating, there is still inevitable defects (insufficient anti-corrosion performance). In this paper, the functional graphene oxide (TDPG) is prepared via self-prepared polymer ( triethylene tetramine-polyethylene glycol diglycidyl ether). The TDPG is used to modify waterborne polyurethane (WPU) coating for improving anti-corrosion property. The electrochemical impedance spectroscopy and salt spray test are used to evaluate the corrosion resistance ability of composite coating. The WPU/ TDPG0.05 owns optimal corrosion resistance property. After 30 days immersion in 3.5 wt.% NaCl solution, the impedance modulus Zf = 10mHz of WPU decreases to 6.17 × 106 Ω·cm2 from 1.36 × 107 Ω·cm2, but the Zf = 10mHz of WPU/TDPG0.05 decreases to 9.48 × 106 Ω·cm2 from 2.39 × 107 Ω·cm2. By Tafel test, the corrosion potential of WPU/TDPG0.05 is -0.056 v, which is more positive than that of WPU (-0.224 v). The corrosion current and polarization resistance of WPU/TDPG0.05 are 1.30 × 10-8 A/cm2 and 3.4 × 106 Ω·cm2, respectively. Moreover, the adhesion strength of WPU/TDPG0.05 decreases to 5.89 MPa from 6.69 MPa, only losing 16.96 %.