Effective synergistic effect of Al2O3 and SiC microparticles on the growth of carbon nanotubes and their application in high dielectric permittivity polymer composites

Abstract

Owing to their excellent intrinsic properties, carbon nanotubes (CNTs) have been widely used to reinforce polymer composites. However, CNT aggregation, the poor CNT/matrix nanoscale interface and increased viscosity are perplexing issues limiting the applications of CNTs in polymer composites. A potential solution to achieve high dispersion states relies upon the concept of micro/nanoscale structures. Previous studies have reported a new generation of composites based on the hybridization of CNTs with ceramic microparticles, providing outstanding properties when used as fillers in polymer composites. Nevertheless, opportunities still exist to improve the performances of these composites further by mixing different types of CNT–ceramic hybrids in properly adjusted proportions. This work focuses on the growth of CNTs on different mixtures of alumina microspheres and silicon carbide microplatelets by floating-catalyst chemical vapor deposition (CVD). Not only do the poly(vinylidene fluoride) composites prepared with the as-synthesized hybrid mixtures exhibit significant improvement of the dielectric properties than those reinforced with either component alone, but also the CVD process yields an abnormally high CNT mass yield when the two types of ceramic particles are simultaneously used as a substrate for the growth. The underlying mechanisms regarding both the CNT growth and the dielectric behaviour of the polymer composites were thoroughly investigated and discussed.