Influence Of Temperature On Electrical Tree Properties Of Epoxy Resin/Montmorillonite Nanocomposites

Epoxy resin based nanocomposite with its good comprehensive performance is becoming a new type of insulation materials in the field of electrical insulation and electronic industry, but electrical tree properties of epoxy resin nanocomposites under high electric field has not yet received enough attention,especially the effect of temperature on the process of electrical trees in the epoxy resin composite remains to be further studied.In this paper, montmorillonite/epoxy nanocomposites prepared by ultrasound technique are used for the study. The effects of temperature on conductivity properties, dielectric constant and loss tangent value are analyzed using the control variable method and the influences of temperature on electrical trees are mainly studied. A kind of device is designed and produced which has the function of heating and real-time observing the branches phenomenon in polymer insulating materials and its complex, which consist with adjustable temperature experiment box and CCD digital camera system. And this device is mainly used to observe and record electrical tree growth. For example, the effects of temperature on electrical tree initial voltage of 50% rate and the electrical tree initiation and growth process are studied.The microstructure of the composite is analysised by scanning electron microscopy(SEM), The results show that the dispersion of MMT particle prepared by high speed mechanical agitation and coupled with ultrasonic technology is very uniform, and no obvious phenomenon of reunion. The conductivity and dielectric loss properties are studied. The experimental results show that the addition of montmorillonite can reduce the conductivity of epoxy resin in high temperature, and the relative dielectric constant and dielectric lossangle tangent value reduces in different extent, and the increases amplitude decrease with temperature. Due to strong interface bonding effect made polymer molecular chain between montmorillonite layers limited, and decreases the conformation number and the dipole polarization relaxation process is limited.For further exploring the electrical properties of dielectric, the growth of electrical tree is studied. The experimental results show that the addition of MMT can significantly improve the initial voltage of the electrical trees. Compared with the pure epoxy, the electrical trees lengths of MMT content of 3%composite decreased obviously at the different temperature. And with the improvement of test temperature, the length of electrical trees in the pure epoxy is increasing and the branch channel becomes thick and black, while the electrical tree in the composite from branch to the forest. This suggests that the addition of montmorillonite significantly improved the electrical tree property of the epoxy resin.