Abstract
It is well known that carbon nanofillers (CNFs) enhance the stiffness, electrical 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 AC electrical field to liquid suspension including CNFs make CNFs align in the electrical field direction. In this paper, the microscopic structure of carbon nanofiller/epoxy composites was controlled by using AC electrical field, i.e. carbon nanofillers were aligned unidirectionally in resin. The alignment of CNFs was in-situ observed during fabrication by using an optical microscope, and the effects of applied voltage, frequency and the weight fraction of CNFs on microscopic structure were investigated. Furthermore, thermal conductivity, electrical conductivity and mechanical properties of composites were measured. The results show that CNFs in uncured epoxy resin align in the AC field direction and form a chain-like network, and that the applied voltage and weight fraction affect the morphology of the chain-like network. Unidirectional alignment enhances the thermal and electrical conductivities, and affects mechanical properties.
