Polypropylene nanocomposites doped with carbon nanohorns for high-voltage power cable insulation applications

Due to the need for high-performance insulating materials for high-voltage direct current (HVDC) power cable applications, nanocomposite strategies that incorporate small amounts of various kinds of inorganic to carbonaceous nanoparticles as an insulating filler into polymer matrix are receiving great attention. In this study, we first utilized carbon nanohorns (CNHs) with unique "dahlia-like" structure and high specific surface area as an insulating filler for improving the insulating properties of isotactic polypropylene (iPP). Through melt mixing, the CNHs with a low content below 1.0 phr were finely dispersed in the iPP matrix and acted as nucleating agent to help crystallization of the iPP molecules. The iPP nanocomposites doped with CNHs exhibited increased AC and DC breakdown strength (BDS) by 9 and 29% compared to those of the pristine iPP at 0.1 phr CNHs, and the CNHs outperformed other carbonaceous fillers including carbon black, carbon nanotubes, and graphite in terms of enhancing DC BDS value of the iPP. In addition, doping of the CNHs was effective not only for suppressing the space charge accumulation during polarization but also releasing the residual charges during depolarization in the iPP at 1.0 phr CNHs. We anticipate that the CNHs-doped iPP nanocomposites will be an important option to replace the traditional crosslinked polyethylene insulator for next-generation HVDC applications.Graphical AbstractDoping a small amount of carbon nanohorns significantly enhanced the high-voltage insulation properties of polypropylene.