Effect of initiator nature on ionic conduction in radiation cured epoxies

Radiation-cured epoxy networks are promising materials for a number of applications for which both high mechanical and dielectric strength are required. In this work, epoxy materials are manufactured via a cationic mechanism which requires an initiator, generally an onium salt, to trigger the cross-linking process under ionizing radiation. It has been established that both the nature of initiator and its content have an impact on the network properties in terms of thermal and mechanical behaviour. We show in this contribution that the increase in chain mobility (decrease in Tg) along with the presence of residual ions results in space charge polarization, increasing both dielectric permittivity and losses under low frequency AC field. This effect also promotes build-up of heterocharges at moderate DC field.