Research On Nanocomposite Conductive Epoxy Resin Coatings

Because of its unique microstructure, nanoparticles have special optical, electrical andmechanical properties which are different with traditional materials and are extensively used in theconductive coatings. Nanoparticles are easy to agglomerate and their dispersity and compatibility ispoor for the surface effect caused by the unique microstructure. All the disadvantages influence andrestrict the application of nanoparticles to a certain extent.In this paper, we used epoxy (EP) as matrix, polyamide as curing agent, multi-walled carbonnanotube (MWCNT-OH) and nano-copper powder (Cu) as conductive fillers in accordance withdifferent purpose of conductive coatings. The MWCNT-OH/EP and Cu/EP nano-compositeconductive coatings prepared by co-mixed method were treated with physical means of mechanicalagitation and ultrasonic dispersion. The effects of MWCNT-OH content and Cu content, differentkinds of silane coupling agents and surfactants on electrical properties, mechanical properties, reagentresistance, humidity resistance and electrochemical protective performance of conductive coatingswere studied. The micro morphology of the coatings were characterised by SEM. The research resultsshowed as follows:1.The addition of MWCNT-OH can improve electrical properties, mechanical properties, reagentresistance, humidity resistance and electrochemical protective performance of MWCNT-OH/EPconductive coatings. For Cu/EP conductive coatings, the addition of Cu can enhance the conductivityand hardness while decrease impact and reagent resistance.2.Silane coupling agents content can improve the dispension of nanoparticles in the matrix andinterfacial adhesion between nanocomposites and metal substrate, and then the comprehensiveperformance of the coatings were enhanced effectively. When the mass of three silane couping agentsKH550, KH560, KH570were respectly the same as MWCNT-OH and2.5%of Cu, two kinds ofcoatings had the best properties. By contrast, the comprehensive performance of the coatingscontaining KH560were better than that with KH550and KH570. In comparison with coatingswithout the silane couping agents, the electrical conductivity of the4%MWCNT-OH/EP and70%Cu/EP coatings was improved by two orders of magnitude respectively. The handness of them whichwas both2H became4H and3H and the corrosion current density of them was reduced by one andthree orders of magnitude.3.The comprehensive performance of coatings which were produced with conductive fillings modified by surfactants was further improved compared to the coatings with silane couping agents.When the content of two surfactants TritonX-100and SDBS was respectly the same as and half ofMWCNT-OH,1%and3%of Cu, both4%MWCNT-OH/EP and70%Cu/EP coatings had the bestproperties. In comparison, the comprehensive performance of the coatings whose fillings weremodified by TritonX-100was better. Compared to the coatings whose fillings were without surfacemodification, the electrical conductivity of two coatings was raised by two orders. The handness ofthem which was both2H became over4H and3H and the corrosion current density of them wasreduced by three orders of magnitude respectively.