Preparation And Electrical Properties Of Epoxy Composites Filled With Two-Dimensional Nano-Fillers

Epoxy resin composites are widely used insulating materials in the electrical field.However,they are prone to charge accumulation on the surface.which can lead to electric field distortion and surface flashover,which affect their insulation performance.Therefore,promoting the surface charge dissipation of epoxy resin composites is a key to improving the insulation properties of the materials.In this paper,two-dimensional sheet-like nanofillers,graphitic carbon nitride(g-C3N4)nanosheets and graphene oxide(GO)are used as modified fillers,and N,N-dimethylformamide(DMF)is used as a dispersant.A series of epoxy resin composite materials were prepared,and the influence of nano-fillers on the structure and morphology,thermal properties,dielectric properties and surface charge dissipation properties of the composite materials was studied,and the effect of DMF removal methods on the structure and performance of the composite materials was analyzed.Impact.The DMF added in the epoxy resin preparation process will decompose to produce dimethylamine when the epoxy resin is cured,which acts as a terminator and reacts with the epoxy group to reduce the crosslink density and glass transition temperature(Tg)of the epoxy resin.Suppress its surface charge dissipation and reduce breakdown strength.By heating before curing the epoxy resin,more than 90%of DMF can be removed,and the performance of the cured epoxy resin material is basically the same as that of pure epoxy resin without DMF.The CN/EP composite material doped with g-C3N4 nanosheets was prepared,and the results showed that the g-C3N4 nanosheets were well dispersed in the epoxy resin matrix,and the thermal stability of the CN/EP composite material was improved.At the same time,the introduction of g-C3N4 nanosheets promoted the movement of macromolecular chains and reduced Tg.In addition,due to the extremely wide forbidden bandwidth and high conductivity barrier of g-C3N4 nanosheets,the binding ability of atomic nuclei is extremely strong,and the number of shallow traps in CN/EP composites has increased significantly,thereby increasing the dielectric constant and charge dissipation rate,0.75 Compared with pure epoxy resin,the charge dissipation rate of wt%CN/EP-DMF is increased by nearly 250%.GO/EP composites doped with GO were prepared.The study found that GO can be well dispersed in the epoxy resin matrix,and the Tg and thermal stability of GO/EP composites have been improved to a certain extent.Due to the strong interaction between GO and the epoxy resin matrix,the dielectric constant of GO/EP composites has increased while the dielectric loss is still maintained at a relatively low level.With the introduction of GO,the charge dissipation rate of GO/EP-DMF composites has a greater increase than EP,which should be attributed to the tiny capacitor effect formed between GO and the epoxy resin matrix.