Unidirectional alignment of carbon nanofillers in epoxy with AC electric field

It is well known that carbon nanofillers (CNFs) enhance the stiffness, electric conductivity and thermal conductivity of polymers. Alignment of carbon nanofillers in polymer is expected to increase the performances in the aligned direction. Several papers have reported that applying alternating electric field to a liquid suspension including CNF's causes alignment of CNF's in the electric field direction. Only a few papers have reported the fabrication of nanostructural controlled composites by using AC field, but the conditions to let CNF's align have not been investigated. In this study, unidirectional aligned carbon nanofiller/epoxy composite was fabricated under AC electric field, and the alignment of CNFs was in-situ observed during fabrication by using an optical microscope. Then, the effects of applied voltage, frequency and the weight fraction of CNFs on nanostructure were investigated. As a result, it is found that CNFs in uncured epoxy resin align in the AC electric field and form a chain-like network, and that the applied voltage affects the morphology of the network.