Effect of gamma-ray irradiation on characteristics of surface charging of polyethylene

Polyethylene (PE) was employed as test sample which was previously irradiated in air up to 100 kGy and then up to 1000 kGy with dose rate of 10 kGy / h by using a ⁶⁰Co gamma-source. The sample surface was corona charged by applying a series of dc stresses on needle electrode which was set 6 mm above the surface. An electrostatic probe was designed to measure the surface charge density immediately after the charging process. Obtained results show dependence of total surface charge upon the applied voltage and the radiation dose. It is suggested that surface charge accumulation depends upon the density of localized surface states, which is alternated by radiation-induced degradation and cross-linking reactions of molecule structure.