Enhanced in-plane thermal conductivity of PP composites with high orientation and rational layered distribution of BNNS

Thermally conductive polymeric materials have attracted great interest from academia and industry for several decades. Herein, we report a facile method to fabricate BNNS/PP composites with excellent properties, especially the in-plane thermal conductivity . SEM and XRD results show the orderly dispersion and high orientation of BNNS along the in-plane direction. Attractively, the in-plane thermal conductivity of BNNS/PP composites after 20 times of folding and hot pressing is dramatically improved to 4.08 W/mk at a BNNS content of only 19.1 vol%, which is 20 times higher than that of pure PP and 480% higher than that of single hot pressing composite at the same filler content. In addition, The Hashin-Shtrikman (HS) model and finite element simulations are introduced to interpret the improvement of in-plane thermal conductivity of BNNS/PP composites after repeated hot pressing. Meanwhile, the influence of parallel orientation and layered distribution of BNNS on the mechanical and dielectric properties of BNNS/PP composites has been investigated. This facile method presents a novel approach to design and fabricate polymer composites with excellent in-plane thermal conductivity.