The Influence Of Epoxy Resin Coatings With Conductive Additives Incorporation On The Bactericidal Performance Of High Voltage Pulsed Electric Field(PEF)

As the increase in the exploration of marine resources, the protection of ships and all kinds of marine facilities becomes more important. In sea water, various kinds of microorganisms, algae and animals can be adsorbed to the hull, which affects ship’s hulls and service life. Anti-fouling coatings have become recognized around the world for the effective method of preventing marine biofouling. To date the inactivation of microorganisms by PEF treatment has not been reported in the field of marine antifouling coatings, and the antifouling effect of PEF treatment has not been assessed.Epoxy resin coatings that provided by Institute of Metal Research were used as base material. CF (carbon fiber)、CB (carbon black) and the composite filler (the mass ratio of CB and CF was0.25) were used as base material and conductive filler, respectively. The content of conductive filler was0,0.01wt.%,0.03wt.%and0.05wt.%). Flavobacterium used in the antibacterial performance experiment were obtained from sea water of South China Sea, which were later screened, isolated, purified, and refrigerated. A drop of cultivated bacterial suspension was added dropwise on different coating samples. The coating samples were put in a treatment chamber to receive the PEF treatment for a few seconds. The sterilizing rates were detected by plate counting method. Additionally, the effects of antifouling coatings on the physicochemical properties after PEF treatment were investigated by using electrochemical impedance spectroscopy (EIS), Raman spectroscopy, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS).In the sterilization experiment of epoxy resin coatings with CF incorporation sterilizing Flavobacterium, the sterilizing rate of epoxy resin coatings without carbon fiber were90.82%and93.18%at11kV and15kV voltage, respectively. The sterilizing rate increases slightly as the carbon fiber length increasing at11kV voltage and0.01wt.%carbon fiber content. The epoxy resin coatings with7mm carbon fiber incorporation achieved sterilizing rate up to99.82%. While the sterilizing rate of the epoxy resin coatings with3mm carbon fiber incorporation peaked at99.73%at the voltage of11kV and the carbon fiber content of0.03wt.%.At15kV voltage, the results of epoxy resin coatings with CB incorporation sterilization experiment show that the sterilizing rate of the coating without CB filler availed the lowest value,93.18%, and while the sterilizing rate of the coating with0.01wt.%CB incorporation was98.51%. As the content of the filler increased, the peak current of the coating sequentially increased under PEF processing, and the sterilizing rate of the coating with0.05wt.%CB incorporation availed a maximum of99.82%.In the sterilization experiment of epoxy resin coatings with CF incorporation sterilizing Flavobacterium, the sterilizing rate of the coating with0.01wt.%composite filler incorporation availed97.13%at15kV voltage. As the content of the composite filler increased, the peak current of the coating slightly increased under PEF processing, and the sterilizing rate of the coating with0.05wt.%composite filler incorporation peaked the maximum of99.59%.The resistance and OCP of epoxy resin coatings have not obvious changes after50h of PEF processing. There were no nearly variations in the Raman spectrum after PEF treatment, beside the intensity of some Raman peaks, which demonstrated that the anticorrosive performances of coatings were hardly influenced after PEF processing, including the molecules and their molecular structure. The results of SEM and EDS indicated that there was no conspicuous variations at coating surface by PEF treatment. And the degradation phenomenon of microcracks and pulverization wasn’t observed after50h of PEF treatment.