Effects of water on the dielectric response of calcined silica-based polyethylene nanocomposites

Abstract

Polymer nanocomposites have become one of the vital research areas in exploring the prospective use of new dielectric materials. Thus far, there have been many positive dielectric results reported, especially for the use of polyethylene nanocomposites as electrical insulation. However, degraded dielectric performances of the materials have also been reported and, in some cases, these have been associated with the presence of water within the materials. In this paper, the effects of water absorption on the dielectric response of polyethylene (PE) nanocomposites containing uncalcined and calcined silicon dioxide (SiO2) nanofillers are reported. The results show that immersing PE/SiO2 nanocomposites under different water immersion periods changes the dielectric response of the materials. Specifically, nanocomposites containing uncalcined SiO2 show a noticeable increase in the real permittivity after water immersion. Meanwhile, under similar water immersion periods, nanocomposites containing calcined SiO2 show a lower real permittivity compared with those containing equivalent amounts of uncalcined SiO2. The mechanisms concerning water absorption of nanocomposites after SiO2 calcination are discussed.