Vertically Aligned Natural Graphite/Thermoplastic Polyurethane Composites for Thermal Management and Electromagnetic Interference Shielding

Abstract

The multifunctional composite with high thermal conductivity and electromagnetic interference (EMI) shielding properties is of great practical application value to many fields [1]. In the past decade, functional fillers were usually incorporated into polymer-based composites to improve their thermal and electrical conductivity. However, these composites only exhibit high horizontal thermal conductivity, limiting their application scenarios, mainly because of poor control over the vertically aligned conductive network. Here, an NG/TPU composite with a high vertical orientation structure is fabricated through a facile laminar hot pressing and wire cutting process. The NG/TPU composite exhibits anisotropic thermal conductivity with thermal conductivity of 26.79 Wm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> and 4.03 Wm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> in the vertical and horizontal directions, respectively; meanwhile, due to the excellent electrical conductivity of natural graphite flakes, the high filling amount ensures that the material has excellent EMI shielding performance in the horizontal direction, up to 50.75 dB. The NG/TPU composites with both excellent thermal conductivity and EMI shielding performance have broad application prospects in EMC (electromagnetic compatibility) and thermal management. Besides, this work provides a promising industrialization strategy to build a vertical functional network for filler-type composites.