| dc.description.abstract | Graphene has high mechanical strength and superb thermal conduction property (up to 5300 W/mK), in addition to flexibility, high mobility and optical transparency. Its excellent properties can improve the most repellent part of polymer materials, with regard to thermal properties. In this study, in order to achieve high surface resistance and high thermal conductivity in the polymer composite, various inorganic fillers including alumina (Al2O3), magnesium oxide (MgO) and boron nitride (BN) with different size were used alone or in combination with graphene to achieve thermally conductive and insulating properties. Polyimide (PI)/graphene (Gra)/ceramic powder composites were prepared by solution blending. In the case where the ceramic powder was separately added, the use of hybrid filler was found to be effective in increasing thermal conductivity of the composite. However, as the amount of addition increases, the mechanical strength of as-prepared film were decrease drastically. Therefore, the incorporation of graphene in this work not only increased the thermal conductivity but also enhance their mechanical properties. Multilayer graphene can significantly improve the mechanical properties of the film for few layers of graphene, especially in MgO. This was believed that the graphene additives may serve as buffer materials among PI/ceramics, which can fill the defect, reduce porosity, and increased density, thereby increasing flexibility. Furthermore, the thermal conductivity of composites, with only 2 wt% of Reduced graphene oxide (RGO) as additives, can significantly increase to 2.26 W/mK, approximately a 1.4-fold enhancement when compared with the results obtained using the same concentration of 50 wt% of hBN; the Al2O3 also has the thermal conductivity of about 1.2 W/mK at a concentration of 50 wt% and addition of RGO 2 wt%. The significant improvement in thermal conductivity can be attributed to the generation of effective thermal conductive pathways formed by graphene and various inorganic fillers in the composite. This study will discuss in detail the role of graphene in thermal conductivity and mechanical properties in composites. | en_US |