Research On Resin Matrix Nonlinear Polymer Composites Applied In Cryogenic Environment

When the cable is running in the electric field,due to the influence of the uneven electric field,it makes the surface and the deep layer of the dielectric material charged,the electrons accumulate in the high resistivity of the dielectric material and difficult to release,which affects the normal work of the cable seriously.A novel resin based nonlinear composite is developed in this thesis.The zinc oxide and carbon black are treated with the silane coupling agent are added to the epoxy resin matrix to modify the properties of it,and the properties of the samples are tested at room temperature and liquid nitrogen environment.Firstly,this thesis proposes a feasible resin formulation.Secondly,the preparation technology of resin based nonlinear composites is studied,and the optimal design of the resin based nonlinear composites is determined.Finally,the curing molds of the resin based nonlinear composites are designed according to different experimental requirements and the required test samples are prepared according to the curing process.The results show that:The conductivity test indicates that the undoped resin matrix composites is linear in the room temperature environment and liquid nitrogen environment,and almost does not vary with the field strength.The effect of temperature on the conductivity that the undoped resin matrix composites changes with the field intensity is greater,and the trend of the conductivity in the liquid nitrogen environment is not as obvious as that in the room temperature.The increase of the inorganic filler concentration help the nonlinearity properties of conductance appear when the electric field intensity is small.The lightning impulse test shows that the breakdown field strength of carbon black/epoxy composite material decreases with the increase of carbon black content,when the breakdown field strength decreases to a certain extent,then begins to increase,finally keeps stable.The breakdown field strength of the zinc oxide/epoxy resin composite material's does not change too much with the increase of the zinc oxide content.Power frequency breakdown test shows that the breakdown field strength tends to decrease with the increase of content of carbon black in carbon black/epoxy resin composite.As the content of zinc oxide in zinc oxide/epoxy resin increases,the breakdown field strength is basically maintained at the fixed value.The mechanical tensile test indicates that the properties of composites in the liquid nitrogen environment are better than those in the room temperature,and the mechanical tensile strength and elastic modulus of the resin composites are basically maintained at the fixed value.