Effect of GO on DC Insulation Properties of Epoxy Composites and Its Application in Anticorrosive Coatings

Abstract

Due to the fact that surfactant in epoxy emulsion can increase electron migration during electrochemical corrosion protection, which reduces the bulk resistivity of epoxy resin, the performance of water-soluble epoxy anticorrosive coatings cannot meet the normal use requirements, which restricts the progress of waterborne anticorrosive coatings. In this paper, GO was used as filler to modify epoxy emulsion to improve DC breakdown performance of polymer composite and reduce leakage current of composite under electric field. The test results showed that when KH550 modified multilayer GO was added to epoxy resin, the neutral salt spray resistance time of the coating was 600 h when the powder addition amount was 1.2 wt%. The initial corrosion voltage was –0.6832 V by Tafel curve test. At this point, the DC breakdown voltage of 35 kV/mm, compared to the pure epoxy resin was increased by 140%, the volume resistivity of 5 × 1016 Ωm., compared to the pure epoxy resin increased two orders of magnitude. It was found that although GO is conductive, a well-dispersed modified GO can be formed into a capacitive structure in epoxy resins, which has the ability to store charge, thereby reducing the leakage current of the material under the electric field and blocking the electronic path. Although this structure has little significance for the application of traditional insulation materials, in the field of anticorrosive coatings, this characteristic of reducing leakage current can assist materials to weaken the occurrence of electrochemical corrosion. Meanwhile, the excellent chemical stability and physical isolation ability of graphene can also guarantee the anticorrosive performance of coatings.