Nanostructural control of carbon nanofiller/epoxy composite by using an alternating electric field

Abstract

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 CNFs causes alignment of CNFs in the electric field direction. Only a few papers have reported the fabrication of nanostructurally controlled composites by using AC field, but the conditions to let CNFs align have not been investigated. In this study, unidirectionally 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 in the end the network structure is hold with cured epoxy. It is also shown that the applied voltage and weight fraction affect the morphology of the network. Furthermore, the network morphology was quantified by using texture analysis. Local homogeneity in the longitudinal and transverse directions of the AC electric field was used. It is found that there is strong relationship between the changes of local homogeneity and network morphology. © 2007 The Society of Materials Science.