Free radical formation in electrical trees in polyethylene

It has been suggested that free radicals may be formed and that they may play a significant role in the electrical treeing process in solid polyethylene (PE).1 The techniques of electron paramagnetic resonance (EPR) should then be advantageous in a study of electrical treeing mechanisms, since EPR responds only to systems containing unpaired electrons, such as free radicals. The hyper-fine structure of the EPR spectra can provide information about the nature of these radicals. In addition, radicals of differing lifetimes, and their evolution with time may be studied by this technique.