Preparation And Electrical Properties Of Nano-MOFs/Epoxy Resin Composites

In recent years,with the continuous development of EHV/UHV DC transmission technology,the problem of electric field concentration of DC high voltage electrical equipment has become more prominent.Suppressing the accumulation of space charge and improving the electric field distribution of key components have become an urgent problem to be solved in DC transmission.Epoxy resin(EP)is used as the insulating material used in the manufacture of key components of DC high-voltage electrical equipment,which determines the main performance of electrical equipment.Therefore,improving epoxy resin performance is the key to solving the problem.In order to achieve electric field homogenization of key components,nano-MOFs are used to modify epoxy resin materials.By adjusting the conductivity characteristics of materials,the effect of space charge accumulation on electric field distribution is eliminated.At the same time,in order to explore whether the different MOFs materials have an effect on the epoxy resin composites,based on the stability requirements of MOFs materials,this paper selects three transition metals(zinc,the outermost electrons with different electron numbers but different extranuclear electron arrangements).Cobalt,zirconium)is the central metal of MOFs.Based on the mechanical synthesis of three stable MOFs materials,ZIF-8,ZIF-67 and UiO-66,nano-MOFs/EP composites with different mass fractions were prepared by blending method.The structure of MOFs was characterized by X-ray diffraction(XRD).The electrical conductivity of nanocomposites was measured by three-electrode system.The space charge distribution of nanocomposites was measured by electroacoustic pulse method(PEA).The dielectric properties of nanocomposites were investigated.The results show that the space charge injection amount of nano-MOFs/EP composites is significantly lower than that of pure EP,and the three MOFs/EPnanocomposites exhibit different conductance and spatial distribution characteristics.ZIF-8/EP composites inhibit space charge accumulation to a certain extent.When the nano-ZIF-8 doping mass fraction is 5%,ZIF-8/EP composites exhibit good nonlinear conductance,to a certain extent.There is a role of homogenizing the internal field strength of the medium.When doped with 1%wt nano ZIF-67 or 5%wt nano UiO-66,MOFs/EP composites have almost no space charge injection under test field strength,showing good space charge suppression effect.Other doping ratios of MOFs/EP composites have very little space charge injection.The conductance characteristics of MOFs/EP composites show that the addition of nano-MOFs changes the interface characteristics of the electrode/medium,increases the threshold field strength of space charge injection,and changes the carrier mobility characteristics inside the medium,thus hindering the space.Charge injection and accumulation.The breakdown strength and dielectric properties tests show that the MOFs/EP composites can meet the actual engineering requirements in terms of breakdown strength and dielectric loss.