Flexible polyurethane/boron nitride composites with enhanced thermal conductivity

Polymer-based composites with high thermal conductivity have great potential application as thermal management materials. This study was devoted to improving the thermal conductivity of the flexible thermoplastic polyurethane (TPU) by employing boron nitride (BN) as heat filler. We prepared flexible and thermally conductive TPU/BN composite via solution mixing and hot pressing. The thermal conductivity of the TPU/BN composite with 50 wt% BN (32.6 vol%) reaches 3.06 W/m·K, approximately 1290% enhancement compared to that of pure TPU (0.22 W/m·K). In addition, the thermal conductivity of our flexible TPU/BN composite with 30 wt% BN is almost not varied (a decrease of only 2.5%) after 100 cycles of mechanical bending, which indicates the high stability of heat conduction of our flexible TPU/BN composite under mechanical bending. The maximum tensile strength of the TPU/BN composite with 5 wt% BN is 48.9 MPa, 14% higher than that of pure TPU (43.2 MPa). Our flexible and highly thermally conductive TPU/BN composites show promise for heat dissipation in various applications in the electronics field.