Decay behavior of surface charge on gamma-ray irradiated epoxy resin

Epoxy resin (ER) laminate was employed as sample to investigate the effects of gamma-ray irradiation on dynamic behavior of surface charge decay. Before the test, the samples were irradiated in air up to 100 kGy and then up to 1000 kGy with dosage rate of 10 kGy / h by using a ⁶⁰Co gamma-source. The experiment was carried out at room temperature with relative humidity of ~ 50%. The sample surface was corona charged by applying dc voltage of ± 4 kV between needle-plate electrodes. An electrostatic voltmeter was employed to measure the surface charge. Obtained results show that with the increase of the radiation dose, the dissipation time of surface charge tends to decrease, which indicates that the charge decay is accelerated by the irradiation. It is suggested that the charge decay behavior is dependent upon the trap characteristics and moisture absorption at surface layer that are altered by the radiation induced chemical reactions.