Surface charge accumulation and decay of epoxy nanocomposites with TiO2 particles

Epoxy resin used as insulating material in electronic and electrical devices plays an important role in system reliability. Addition of nanoparticles into epoxy can improve the dielectric properties comparing with the undoped materials. However, due to the change of the material structure, trap characters and charge behaviors are altered as a response. This possibly leads to a great risk of electric field distortion and discharge that degrades the insulation. From the viewpoint of safety, it is necessary to investigate the charge behavior on epoxy nanocomposites. This paper presents study aimed at clarifying the effect of nano-filler content on surface charge accumulation and the decay behaviors of epoxy nanocomposites with TiO2 particles. The samples were prepared by dispersing nano-scale TiO2 into epoxy resin by mixing with shear force. Corona charging tests were independently performed at room temperature with the same relative humidity. Surface charge distribution was measured by means of an electrostatic voltmeter. Obtained results show the dependence of the accumulated charge as well as the charge decay rate upon the different concentration of TiO2 that is varied as a function of the charge polarity, charging time and charging voltage. It is suggested that the charge dynamics is dependent upon the characters of localized surface states that are altered by the nanoparticles, which induces chemical reactions.