Electrical tree propagating characteristics of polyethylene/nano-montmorillonite composites

Electrical tree occurring in polymer insulation limits the applications and reduces the service lifetime of power equipment. To improve electrical tree resistance in polymer insulation, polyethylene (PE) nanocomposites with nano-montmorillonite (MMT)- layered fillers are compounded and investigated in terms of electrical tree characteristics. By an organization process, intercalation and coupling agents are used to modify the inorganic-layered MMT nanofillers in sequence. Polyethylene/nanomontmorillonite (PE/MMT) composites with different MMT contents are prepared by melting intercalation. Fourier transform infrared spectrophotometry is used to determine the chemical characteristics of the MMT in different surface-modification stages. The crystalline morphologies and MMT distributions in the composites are characterized by polarizing microscopy and scanning electron microscopy. The electrical tree propagating characteristics and corresponding conduction properties of the PE and PE/MMT composites are investigated. Results show that the electrical tree resistance of PE/MMT composites significantly improves. The electrical tree length decreases and the fractal dimension increases in PE/MMT composites compared with pure PE. After performing electrical tree initiation, conductive current slightly increases in composites but decreases in PE. This result suggests that the characteristics and conductive mechanism of electrical tree differ between PE and PE/MMT.