Study of temperature effects on the electrical behavior of polypropylene-clay nanocomposites submitted to electron beam irradiation in a SEM.

Charge transport and electron emission properties in polypropylene and its nanocomposites filled with nanoclay particles submitted to an electron irradiation, in a Scanning Electron Microscope (SEM), are investigated using induced displacement and leakage currents. The measurements have been performed at various temperatures ranging from 20°C to 75°C at a primary beam energy of 20keV and a primary beam current of 1nA with the aim to highlight the effect of temperature and nanoclay content on these properties. The results show, at a given temperature, that the incorporation of clay in polypropylene (PP) matrix paradoxically leads to a concomitant increase in the electrical conductivity and the charge accumulated. In contrast, if the clay content is fixed, there is an increase in conductivity and a reduction of the charge accumulated when the temperature increases. The mobility of charge carriers and the corresponding activation energy are deduced from the measured leakage current during discharging step. The mobility was found to be an order of magnitude higher for the nanocomposites. The study of the influence of the temperature and nanoclay concentration on electron emission yield is also addressed.