Thermal\nConductivity of Polymer-Based Composites with Magnetic Aligned Hexagonal\nBoron Nitride Platelets

Abstract

Hexagonal boron nitride (hBN) platelets\nare widely used as the reinforcing fillers for enhancing the thermal\nconductivity of polymer-based composites. Since hBN platelets have\nhigh aspect ratio and show a highly anisotropic thermal property,\nthe thermal conductivity of the hBNs-filled composites should be strongly\nassociated with the platelets’ orientation. However, the orientation\neffect has been explored less frequently due to the technical difficulties\nin precontrol of the platelets’ orientation in the polymer\nmatrix. In this paper, we report the use of magnetic fields to assemble\nthe platelets into various microstructures and to study the thermal\nconductivities of the designed composites. The experimental results\nshowed that thermal conductivities are dramatically different among\nthese composites. For instance, the thermal conductivities of the\ncomposites with platelets oriented parallel and perpendicular to the\nheat flux direction are respectively 44.5% higher and 37.9% lower\nthan that of unaligned composites at the volume fraction of 9.14%.\nThe results were also analyzed by a theoretical model. The model suggests\nthat the orientation of the hBN platelets is the main reason for the\nvariance in the thermal conductivity.