Dielectric Properties and AC Conductivity of Epoxy/Hybrid Nanocarbon Filler Composites

摘要

24.1 Introduction Discovery of nanoscaled carbon materials such as carbon nanotubes (CNTs), graphite nanoplatelets (GNPs), and graphene and the development of nanocarbon-based polymer composites open new era in material science and technology [1]. Nanoscaled carbon fillers exhibit a range of remarkable properties, such as exceptional Young's modulus, high tensile strength, excellent thermal and electrical conductivity, and high surface area [2, 3]. Graphene, which consists of several stacked graphene sheets, shows many extraordinary properties such as high carrier mobility, mechanic stiffness, and fascinating electromagnetic response [4, 5]. Compared with graphene, GNPs exhibit good mechanical and electrical properties [6] and have much lower production cost and better stability. Due to these outstanding properties, nanocarbon materials are the most promising fillers to improve mechanical and physical properties of composites. In particular, the incorporation of highly conductive nanocarbon particles into different polymers (epoxy, polypropylene, poly(vinylidene fluoride), polystyrene, etc.) [6-8] allows to create the new nanocomposites with tunable electrical properties. The most important feature of reported composites is very low percolation threshold in electrical conductivity due to high aspect ratio of carbon nanoparticles and easy formation of conductive network in composite. Furthermore, nanocarbon-based polymer composites are very perspective for applications in electromagnetic shielding and high-energy-density capacitors, owing to unique property of dramatic increase in their dielectric constants near the percolation threshold.