Effect of pulse stress on surface charge of epoxy nanocomposites with TiO2 particles

Epoxy resin has become an integral part of electronic and electrical devices where the material is exposed to pulse stress. Surface charge accumulation and decay of charged dielectric materials are very important parameters related to the electrical properties of the material. Nano-composite technology makes it possible to improve electrical properties of insulating materials. Therefore, it is important to investigate the dynamic behavior of surface charge decay influenced by the nano filler on epoxy resin. In this paper, it was attempted to clarify the effect of pulse stress on the electrical properties of epoxy resin nanocomposites focused on the surface charge accumulation and decay based on the TiO2 nano-filler. Prior to test, the samples were prepared by dispersing nano-scale TiO2 into epoxy resin by mixing with shear force. Corona charging and decay tests were independently performed at room temperature with the same humidity. The surface charge distribution was measured by means of an electrostatic voltmeter. Obtained results show the dependence of the accumulated charge density as well as the charge decay rate upon the different nano filler loading that is varied as a function of the rise time of pulse stress. It is suggested that the charge dynamics is dependent upon the characteristics of localized surface states that are altered by the nano filler induced chemical reactions.