The UCR team has recently determined that graphene composites reach a distinctive thermal percolation threshold at the loading fraction above 20 vol.%. Thermal percolation is a term used to describe formation of the continuous interconnecting network of fillers, allowing heat to travel mostly via these thermal conductive passes rather than through the matrix. The team established that graphene fillers outperformed boron nitride fillers (h-BN) – another highly thermally conductive material – in the thermal conductivity enhancement. The reported study clarified the debated mechanism of the thermal percolation, and it is expected to facilitate the development of the next generation of the efficient TIMs. “The unexpected finding of this study was that the thermal properties of composites with the high loading of graphene are strongly influenced not only by the in-plane thermal conductivity of few-layer graphene fillers but also by their cross-plane thermal conductivity,” Balandin explains to Nanowerk. “In such composites, heat mostly travels via the thermally conductive pathways of few-later graphene. As a result, heat transfer from one graphene filler to another graphene filler – across the atomic planes and interfaces – becomes the bottleneck for thermal transport.” Read More…
