| Epoxy resin(EP)is widely used in electrical equipment insulation,but the rapid development of high-voltage transmission and electronic packaging has put forward higher requirements for epoxy resin performance.Single-performance materials are difficult to meet the requirements of use.Therefore,inorganic micro-and nano-fillers were added to the epoxy matrix as the dispersed phase.The electrical and thermal properties of epoxy resin and its composites were studied,it is of great significance to develop new dielectric materials with excellent dielectric properties.On the basis of current research status of polymer-based nanodielectric,purposed to explore the dielectrical property of micro-and nano-dielectric,different epoxy resin composites were prepared severally via melting intercalation method,in which,bisphenol A epoxy resin was recommend as matrix,and disparately treated montmorillonite and calcined silicon carbide were dispersed phase.The montmorillonite(MMT)was treated by intercalation agent and pre-dispersed by ultrasonic vibration.The lamellar spacing of montmorillonite before and after organic modification was characterized by X ray diffraction(XRD).Scanning electron microscopy(SEM)was used to observe the morphology of the packing and its dispersion in the matrix;The high-resistance meter,industrial frequency AC breakdown test platform,high-voltage schering bridge with high and low temperature test chamber and broadband dielectric spectrometer were used to test the material's conductance,breakdown,relative p ermittivity and loss parameters.The differences of dielectric properties between pure epoxy resin,nanocomposites,microcomposites and micro-nano composites were compared.The experimental results show that the lamellar spacing of the modified montmorillonite increased from 1.24nm to 2.13nm,and the lamellar spacing increased by 71.8%;the filler dispersed evenly in the EP matrix without obvious agglomeration.The introduction of micro Si C and nano MMT inorganic particles can improve the conductivity and nonlinear coefficient of the composite compared with pure EP,and reduce the threshold field strength.When the ratio of Si C/MMT increases,the conductivity of the composite increases,while the nonlinear conductivity characteristics decreases.At low temperature,the conductivity of Si C/EP composite and MMT/EP composite is lower than that of pure EP,but at high temperature,the conductivity of EP increases most obviously,which is higher than that of composite,The influence of Si C/MMT ratio on the conductivity of the composite is lack of obvious regularity.So MMT can improve the nonlinear conductivity of the composite;Nano MMT particles can improve the breakdown strength of epoxy matrix composites.The breakdown strength of 5N component samples in a single filler composite was 43.05%higher than that of pure EP.When the mass ratio of MMT to Si C was 3:2,the maximum value was 53.46kv/mm,which was 45.67%higher than that of pure EP.The results of dielectric temperature spectrum show that the introduction of inorganic fillers makes the?_r and tan?values increase compared with pure EP.At 120°C,the?_r and tan?values of each sample are phased with temperature.In the range of 20°C?120°C,the values of?_r and tan?of each sample remained basically unchanged.When the temperature reached 120°C,?_r and tan?began to increase rapidly.The test results of dielectric spectrum show that the introduction of inorganic fillers makes the?_r and tan?values increase compared with pure EP.The?_r of each sample decreases with the increase of frequency,and tan?decreases first and then increases with frequency Change the law. |
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