The Changs Of Electrical Properties Of MMT/SiO₂/LDPE Nanocomposites Under AC Field Strength Effect

In the study of dielectric properties of polymer,many studies have shown that adding inorganic nanoparticles into polymer can improve some electrical and other properties of the material and make it more widely used in practical engineering.When polymer is used in engineering as the filling material of insulating structure,it is often necessary to evaluate and predict its various electrical properties,so as to ensure the normal operation of power system.LDPE is often used as insulation material of electrical equipment or cable in electrical engineering,and the research on the aging performance of LDPE plays an important role in evaluating the insulation life of electrical equipment.In this paper,LDPE,MMT/LDPE,Si O₂/LDPE and MMT/Si O₂/LDPE nanocomposites were prepared by melt blending method with LDPE as matrix,hydrophobic modified nano-silica?Si O₂?and ultrasonic organic montmorillonite?MMT?as filler.The experimental sample of the material is a round sheet with thickness of 200?m and diameter of 10cm.The materials were aged at the AC field strength of 32.5k V/mm,i.e.6.5k V.The aging time was 0h,200h,400h and 600h respectively.The breakdown field strength,dielectric loss characteristics,space charge characteristics and partial discharge characteristics of materials in different aging period were measured,and aging and other properties of different systems were compared.After aging,the dielectric loss increased,the breakdown field strength decreased,and the space charge and PD characteristics changed.It was found that the aging properties and aging properties of LDPE were improved by adding nanoparticles,and the improvement of material properties was different in different aging period.Within 200h of aging,the properties of MMT/LDPE are more stable than the other three materials,and the properties of Si O₂/LDPE and MMT/Si O₂/LDPE are better than MMT/LDPE under longer-term aging conditions.The difference is due to the different combination mode of two kinds of particles and molecular chain and the formation mechanism of interface.At last,it is speculated that the synergistic effect may appear if the two particles are mixed in proper proportion,so as to further improve the properties of the materials.