Thermal and breakdown properties of polypropylene homopolymer, copolymer, and blend

Abstract

Polypropylene has been widely used in high voltage insulation. This material has recently been regarded as to potentially compensate conventional limitations of XLPE such as being difficult to recycle and having significant space charge accumulation and poor thermal conductivity. Currently, there are various types of polypropylene produced in the market. Therefore, this research attempts to investigate the breakdown performance of several types of polypropylene, namely, polypropylene homopolymer, polypropylene impact copolymer, and the combination of both in 50:50 ratio. The thermal behaviors of the samples were characterized using scanning calorimetry (DSC). The thermal characterization demonstrates that all types of polypropylene have a similar melting temperature of about 162 °C. Besides that, the breakdown test reveals that polypropylene homopolymer has the highest DC breakdown of 278 kV/mm. Meanwhile, polypropylene impact copolymer has the lowest breakdown strength of 109 kV/mm and 239 kV/mm under the applied AC and DC fields, respectively.