Large contact areas tend to decrease interfacial thermal resistance between the nanofillers and the epoxy matrix. This is because long and convoluted BNNT networks facilitate the connection of adjacent BNNSs, resulting in a highly effective thermal network and simultaneously low interfacial thermal resistance through increasing nanofillers/matrix contact area. However, at contents higher than 1% wt., BNNTs were not effective in improving the thermal conductivity of 30 wt% BNNSs/epoxy composites due to increased phonon scattering density by internanotube junctions. 21 The efficiency of the fillers in thermally conductive materials was characterized by the thermal conductivity enhancement (TCE), which is defined as where K is the thermal conductivity of the composite and Km is the thermal conductivity of the matrix material. Table summarizes some recent results from literature on the thermal conductivity of various epoxy composites that used BN-based fillers. Based on our understanding, the thermal conductivity value obtained in this study for the epoxy composites with BN-based hybrid filler content is higher than the previously reported values. We believe that this is due to the BNNSs acting as the primary pathways for thermal conductivity within the composites, with the BNNTs facilitating connections between the BNNSs. Furthermore, the method used in this study is comparatively straightforward and efficient when compared to modifying the BN surface using strong acids or bases.