Enhancing the thermal and electrical performance of epoxy microcomposites with the addition of nanofillers

Two different types of microcomposites, namely alumina and silica microcomposites, were reinforced with nanosized fillers, and their thermal and electrical properties were investigated. It was shown that the addition of small amounts of nanosized fillers (less than 1 vol %) improves both the thermal and electrical performance of microcomposites based on epoxy. The addition of 0.6 vol % of nanosized hexagonal boron nitride to silica microcomposite increases the thermal conductivity by 30%, the AC breakdown strength by 65%, and finally, the DC breakdown strength by 50%. Important parameters that affect the performance of micro-nanocomposites are the interaction between the particles and matrix and water uptake. The surface modification of the nanoparticles results in a good adhesion between the particles and matrix, which gives epoxy a more rigid structure. Furthermore, nanoparticles and their interfacial layers increase the interaction between the microparticles because they bridge the unfilled gaps between them. On the other hand, water uptake negatively affects the electrical performance of composites, and it has been shown that water uptake positively depends on the fill grade. The quality of the production procedure is an important factor that significantly affects the performance of composites. Composites with increased mass density have higher probability of including structural imperfections such as voids, which degrade both the electrical and thermal properties. Finally, the experimental results show that materials used already in industry can be improved by adding only a small amount of nanofillers, reflecting the potential of nanotechnology in the field of dielectrics.