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Study on AC/DC Breakdown Strength and Space Charge of Nano-MgO /Polypropylene Composite

The electrical and thermal characteristics of isotactic polypropylene (i-PP) are revealed to be superior to polyethylene (PE), and i-PP is suitable for recycle use as the recent environmental requirement. The electrical characteristics of nano-filler/PP composite are investigated and studied in this paper. Nano-particles of MgO were added to i-PP to prepare nanocomposites for testing of AC/DC breakdown strength (BDs) and distribution of space charge. It is found that MgO nano-particals improve AC BDs (breakdown strength) of PP, while DC BDs decreases with loading of nano-MgO. The value of DC BDs is higher than that of AC BDs. The distribution of space charge was investigated by PEA devices, and few volume of space charge appeared in PP under low electrical field (10 kV/mm and 30 kV/mm). A lot of Heter-opolar space charges appeared in PP under electrical field of 50 kV/mm. The volume of space charge decreases with increase of particles' concentration. It is revealed that nano-MgO is considered to have an effect of suppression of charge injection in PP composite.