On the Effects of TiO2 Additive on D.C. Conductivity and Morphology of Polyethylene

Abstract

The effects of doping low density polyethylene (LDPE) with fine particles of TiO2 as an inorganic additive on the d.c. conductivity and morphology of LDPE were investigated using two temperature profiles: the first at constant temperature of 40°C and the second under thermal cycling between 40°C and 80°C in the presence of an electric field. Results indicate that the incorporation of TiO2 in the polymer has increased the charge carrier mobility and the d.c. conductivity of the doped LDPE. Morphological investigations using scanning electron microscopy (SEM) of CCl4 vapour etched surfaces of the undoped and doped materials show that the addition of the inorganic additive to LDPE has considerably changed the morphology of the polymer. It is also shown that the morphology of the doped LDPE has undergone considerable structural changes after thermal cycling in the presence of the d.c. electric field during d.c. conductivity measurements. The role of the additive in increasing the d.c. conductivity and changing the morphology of LDPE is discussed. An attempt is made to correlate between the recorded increase in the d.c. conductivity and the observed morphological changes in the investigated material.