Investigation On Property Of Electrical Tree And Conductance On PP/MMT Composites

Polypropylene (PP) has excellent electrical properties, high breakdown fieldand chemical resistance, so has been widely used in electric power capacitorinsulation materials. But PP has the disadvantages itself that poor toughness,poor low temperature resistance and the electrical trees which leads its insulationaging would emerge in long-term working, all those limit its application greatly.In this paper, using surface modified montmorillonite as the nanofiller, andPP-g-MAH as the compatibilizer, on this basis, PP/MMT composites is preparedby melting intercalation process. Through observing the crystalline morphologyby PLM, PP/MMT which was prepared in two steps and has different content ofmontmorillonite, been researched. As the content of MMT is increased, the spherules sizebecomes smaller and smaller until the Maltase’s pattern has been disappeared. Inaddition, AC breakdown tests and spectrum test of PP/MMT composites havebeen carried out, has discussed the effects on breakdown properties and dielectricloss by different interface domain structure. The optimum content ofmontmorillonite in the two step preparation process has been identified.It has studied on electrical treeing resistance of PP/MMT composites whichhave different preparations by digital shooting system, and has measured theconductivity of the samples. The results show that the conductivity will affect theelectrical tree initiation probability. The samples have been prepared by the twostep process forming the interface structure can capture carrier well, and restrainthe electrical tree initiation effectively.It has studied on electrical treeing resistance of PP material by digitalshooting system and conductance current test. The results show that electricaltree lead to the electrical current smaller. With the development of electric branchlength, the conduction current has increased. The paper has calculated TheFractal Dimension of two kinds of electrical trees by MATLAB7.8, and has discussed the relationship between Fractal Dimension and the conduction current.