Study of dielectric and mechanical properties of epoxy/SiO2 nanocomposite prepared by different processing techniques

This study is aimed to investigate the effect of different processing techniques on dielectric strength of epoxy/SiO₂ nanocomposite. Two processing techniques included in this study are sonication and Thinky planetary centrifugal mixer. Sonication is one of the most widely used mixing techniques in nanocomposite preparation and is believed to provide a good dispersion. However, sonication will produce a lot of air bubbles when disperse the fillers into the epoxy resin which will increase the difficulty of the degassing process. These kinds of small air bubbles may not affect the mechanical properties significantly but may have effects on the dielectric properties. Thinky planetary centrifugal mixer is an innovation mixing technique which can achieve a uniform mixing, dispersal and deaeration in a short time. SiO₂ was mixed with epoxy resin directly using either sonication or Thinky mixing with 2 wt% loading and 5 wt% loading respectively. The mixing time is 20 minutes, 40 minutes, 60 minutes respectively. The same degassing process is applied to both sonication and Thinky mixing specimens. The degassing process includes a vacuum degassing process and a degassing program in Thinky mixer. Breakdown strength tests were then performed to evaluate the effect of processing techniques. Dynamic mechanical analysis was also performed on the samples prepared by Thinky mixer.