Epoxy-Based Nanocomposites for High-Voltage Insulation: A Review

Epoxy nanocomposites, with inorganic oxide nanoparticles as filler, can exhibit novel property combinations, such as enhanced mechanical strength, higher thermal conductivity, increased dielectric breakdown strength, and reduced complex permittivity. Therefore, they have interesting applications in nanodielectrics, such as high-voltage insulation materials or in microelectromechanical systems. The primary challenge in the processing of nanocomposites is achieving a homogeneous dispersion of the nanoparticles. The dispersion quality affects the interfaces between the organic and the inorganic components, which can determine the final properties of the nanocomposite. Here, the processing methods and the resulting dielectric, mechanical, and thermal properties of epoxy nanocomposites with inorganic oxide fillers are presented. Functionalization of the nanoparticle generally improves the dispersion of the particles in the polymer matrix. Different oxide fillers are observed to have similar effects on the properties of the nanocomposites. Epoxy-based nanocomposites exhibit improved dielectric breakdown strength and lower complex permittivity with inorganic oxide nanoparticles at low filler contents, compared to conventional composites with micrometer-sized particles. While there are some inconsistencies in the findings, which may be attributed to differences in the dispersion quality, an improved understanding of the nanoparticle-epoxy interfaces in nanocomposites will enable tailoring of the desired properties, opening new avenues for application.