Magnetically aligning multilayer graphene to enhance thermal conductivity of silicone rubber composites

The increasing demand for packaging materials calls for new technologies to achieve excellent thermal conductivity of polymer composites with low content of thermal conductive filler. This article prepared a kind of magnetically functionalized multilayer graphene (Fe3O4@MG) via electrostatic interactions, which efficiently enhanced the thermal conductivity of silicone rubber (SR) composites by the alignment of Fe3O4@MG in an external magnetic field. The morphology and structure of the Fe3O4@MG together with the thermal conductivity of corresponding Fe3O4@MG/SR composites were systematically investigated by SEM, TEM, XRD, elemental mapping, and thermal conductivity tester. The obtained results showed that Fe3O4@MG was induced to form chain-like bundles in silicone rubber matrix under the applied magnetic field, which enhanced the MG-MG interaction, and formed effective thermal pathways in the alignment direction. Furthermore, as coating mass ratio of Fe3O4@MG increased, the thermal conductivity of randomly oriented Fe3O4@MG/silicone rubber composites (R-Fe3O4@MG/SR) decreased gradually, whereas the through-plane thermal conductivity of vertically aligned Fe3O4@MG/silicone rubber composites (V-Fe3O4@MG/SR) increased even filled with same contents of thermal conductive filler. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47951.