Synergistically enhancing the performance of cardanol-rich epoxy anticorrosive coatings using cardanol-based reactive diluent and its functionalized graphene oxide

In this paper, a new anti-corrosion composite coating with high-volume fraction of cardanol-based components was prepared using epoxy, cardanol-based reactive diluent (602A), and 602A functionalized graphene oxide nanosheets (A-GO). A one-step, low-cost method was adopted to synthesize the A-GO. By synergistically enhancing the matrix compactness, filler dispersibility, and matrix hydrophobicity, the cardanol-rich epoxy composite coating (A-GO/602A/epoxy) shows high anti-corrosion performance in the long term. The morphology and structure analyses show that the A-GO/602A/epoxy composite coating has i. enhanced matrix compactness, ii. optimized filler dispersibility and filler/matrix bonding strength, and iii. improved matrix hydrophobicity. The electrochemical impedance spectroscopy (EIS) test was used to determine the anti-corrosion performance of the A-GO/602A/epoxy composite coating. After immersing in diluent NaCl solution (3.5 wt%) for 90 days, the increase of the impedance modulus of the A-GO/602A/epoxy composite coating maintains three orders of magnitude at low frequencies (0.01 Hz) compared to the pure petroleum-based epoxy coating, indicating that the corrosion properties of the composite coating can be significantly enhanced by synergistically optimization of the three factors. Our results show the high potential of cardanol-rich epoxy coatings in the field of anti-corrosion epoxy coatings, and may give a guide to the design of high-performance anti-corrosion epoxy coatings.