The electrically ruptured area of crosslinked polyethylene

The electrically ruptured areas of failed crosslinked polyethylenes have been investigated using optical microscopy and Fourier transform infrared spectroscopy (FTIR). The formation of well-defined banded spherulites was observed around the ruptured areas. Since spherulites do not occur in crosslinked polyethylenes, the formation of spherulites in failed specimens is considered to be related to breakage of the network during the breakdown process. FTIR results are shown to support this suggestion, revealing that more than oxidation occurred during the breakdown process. This observation contradicts some well-established breakdown mechanisms, such as thermal breakdown. It is also shown that, if the initiation of electrical breakdown involves network rupture, the properties of crosslinked polyethylene could be enhanced by designing less reactive crosslink points