Electrically conductive epoxy nanocomposites with expanded graphite/carbon nanotube hybrid fillers prepared by direct hybridization.

Carbon nanotubes (CNTs) are generally used to promote the electrical conductivity of the polymer nanocomposites. However, in spite of their superior properties, CNT's high cost has limited their commercial application, so far. Thus, the development of hybrid carbon nanomaterials (CNMs) composed of CNTs and cheaper CNMs such as carbon fibers (CFs), expanded graphites (EGs), and graphene nanoplatelets (GNPs) is important in terms of reducing the cost of CNT-based fillers. In this study, we prepared EG/CNT hybrid fillers via direct CNT synthesis on the EG support using modified combustion method and thermal chemical vapor deposition (CVD) method, and investigated the electrical conductivity of the expoxy nanocomposite with EG/CNT hybrid fillers. The epoxy nanocomposites with EG/CNT hybrid fillers at 20 wt% filler loading showed 260% and 170% electrical conductivity enhancement in comparison with the EG and the simply mixed EG and CNT fillers, respectively. Our approach provides various applications including electromagnetic interference (EMI) shielding materials, thermal interface materials (TIMs), and reinforced nanocomposites.