Investigation On Crystalline Morphology And Dielectric Properties Of PP/MMT Nanocomposites

Polypropylene (PP) has superior dielectric properties in high temperature and chemical corrosion-resistant properties, and it is extensively used to power capacitors insulation materials. But isotactic polypropylene (i-PP) easyily electrical aging, so that the application in the field of high-voltage insulation is limited. As the nano-particles have special properties,a small amount of nano-filler can change the property of polypropylene.In this paper, montmorillonite is used to modify polypropylene, and relationships between crystalline morphology and properties are studied. Isotactic polypropylene (i-PP) is used as the base material, and montmorillonite modified by octadesylamine as the nanofiller, and maleic anhydride grafted polypropylene (PP-g-MAH) as the compatibilizer, on this basis, PP/MMT nanocomposite is prepared by melting intercalation process. Effects of different contents of compatibilizer and montmorillonite and temperatures of melting intercalation on the crystalline morphology, space charge and electrical properties of polypropylene are researched. At the same time relations between crystalline morphology, space charge and dielectric properties are analyzed.In this article, crystalline morphologies of PP and PP/MMT nanocomposites are observed by PLM. The results indicate that MMT plays the role in heterogeneous nucleation. When melting intercalation temperature reaches 190℃and the content of compatibilizer is 3%, PP/MMT has the best crystalline morphology. Space charges of PP and PP/MMT nanocomposites are measured by PEA, and the results show that trap levels are changed and that deep traps are filled after adding the montmorillonite into the polypropylene. Studies of electrical properties show that the crystalline morphology has a great influence on it. It is concluded that there is the highest insulation resistivity and the lowest dielectric loss when melting intercalation's temperature reaches 190℃and the content of compatibilizer is 3%, by comparing the different composites.