Hot-pressing induced alignment of AlN whiskers in polymer matrix leading to enhanced in-plane thermal conductivity

With the increased integration of electronic devices, the demands for polymer-based composites with higher thermal conductivity as thermal management materials are gradually growing. Compared with regular spherical morphology, 1D particles with high aspect ratio are regarded as ideal fillers for polymer matrix due to their favorable construction of thermally conductive channels. In this work, high-aspect-ratio AlN whiskers were successfully synthesized by a modified direct-nitriding method, which were further combined with ultra high molecular weight polyethylene (UHMWPE) to prepare the thermally conductive composites by a facile hot-pressing process. The introduction and alignment of AlN whiskers along horizontal direction resulted in a high in-plane thermal conductivity of 7.12 W/(m·K) at the 62.5 wt% filling fraction, which was 16 times than that of UHMWPE. In addition, due to the cross-linking of 1D AlN whiskers, the composites also exhibited high thermal stability and mechanical strength, making them very promising for application as high-performance thermal management materials.