Effects of physical and chemical defects of polyethylene on space charge behaviour

In the field of space charge physics, the significant role of traps on space charge behaviour has been now well-established. However, the traps in polymers are difficult to define whereas in ceramics oxygen vacancies for example are easily identified. In this paper, the relative contribution of “physical” and “chemical” defects on the trapping ability of polyethylene has been investigated. First, the effects of “physical” defects, i.e. morphological changes have been reported. Second, the influence of chemical defects, i.e. oxidized sites has been studied. These latter defects have been created by UV-irradiation resulting in a partial oxidation of the polymer chain. The concentration of oxidized species can be evaluated using F.T.I.R (Fourier Transform Infra-Red) spectroscopy. The trapping ability of sample was studied by using the Mirror-Image method. The results of this study demonstrate that the contribution of “physical” traps to the space charge behaviour of polymers is more significant than that of “chemical” traps. Therefore this study provides a better understanding of traps in polymer and their effects on the space charge behaviour