Thermal Conductivity of Magnetically Aligned Graphene-Polymer Composites with Fe3O4-Decorated Graphene Nanosheets

A facile approach was developed in this study to align the magnetically functionalized graphene nanosheets (M-GNSs) within an epoxy matrix. M-GNSs were firstly synthesized by a modified polyol method with surface modification of Fe3O4 nanoparticles, and then incorporated into epoxy under an externally applied magnetic field. The alignment-dependent thermal conductivity of the M-GNSs/epoxy composite treated with various intensities of magnetic field in the range of 0-1.0 T was examined. Both the good dispersion and high alignment were found in the composites treated above 0.5 T of magnetic field, as verified by the x-ray diffraction and polarized Raman spectra. Thermal conductivity in the aligned direction of 0.5 T-treated composites with 0.52 vol.% filler content (0.361 +/- A 0.018 W/mK) showed enhancements of 111 +/- A 28% and 48 +/- A 16%, compared to that of epoxy (0.174 +/- A 0.014 W/mK) and non-magnetically treated composites (0.252 +/- A 0.019 W/mK), respectively.