Highly Anisotropic, Thermally Conductive, and Mechanically Strong Polymer Composites with Nacre-like Structure for Thermal Management Applications

Abstract

The conventional approach to improve the thermal conductivity (TC) of polymers by blindly adding inorganic fillers suffers from the limited TC enhancement (<3.0 W/mK) with isotropic TC and poor mechanical performance. Here, highly anisotropic, thermally conductive, and mechanically strong boron nitride (BN)/ultrahigh molecular weight polyethylene composites are prepared via a facile solid-phase extrusion (SPE) technology. The in-plane TC approaches 12.42 W/mK at the BN loading of 50 vol %, which is 242% higher than that of the high-pressure compressed counterpart (3.63 W/mK). The anisotropic index of TC reaches as high as ∼1000%, allowing the heat transfer more readily along in-plane direction than through-plane direction as revealed by infrared imaging results. We attribute the increased TC to the unique nacre-like structure induced by the flow-assisted alignment. BN platelets are highly oriented to form connected thermal conductive pathways for phonon transport along the basal plane. The interfacial the...