Space charges in low density polyethylene

It is established that on application of an external electric field a dielectric absorption occurs in polyethylene, resulting in a polarization which persists even after the removal of the polarizing field. This persistent polarization (electret behaviour) in a non-polar semicrystalline polyethylene film may arise from an injection of charge carriers (electrode injection) and their subsequent localization in the polymer. Such charges may also be prevalent in the virgin polyethylene films as impurity ions. Present work investigates the nature of the dielectric polarization as a function of charging fields before and after hexane treatment of low density polyethylene (LDPE) films using a thermal current transient technique. LDPE films of 75 μm thickness were kindly provided by the Monsanto Chemical Company of Great Britain.