Highly thermally conductive polystyrene/polypropylene/boron nitride composites with 3D segregated structure prepared by solution-mixing and hot-pressing method

Continuous heat conduction networks are very significant for filler-filled polymer composites to enhance their thermal conductivity (TC). 3D segregated structure has been considered as an effective approach to construct continuous heat conduction networks. Herein, we prepared the polystyrene/polypropylene/boron nitride (PS/PP/BN) ternary composites with 3D segregated filler networks by solution-mixing and hot-pressing method. The ternary PS/PP/BN composite containing 50 wt% BN achieves TC of 5.57 W/m.K, which is 29 times than that of PS resin (0.19 W/m.K) and 2.76 folds of the PS/BN binary counterpart (2.02 W/m.K). More importantly, the ternary PS/PP/BN composite exhibits favorable thermal stability after 50 hot-cold cycles or thermal ageing test for 50 h, whose TC drops slightly by 3.2% and 3.4%, respectively. The typical 3D segregated structure has been constructed in our PS/PP/BN ternary composites, which can provide effective heat conduction pathways. Moreover, BN platelets align along the PP microspheres in the PS matrix during the hot-pressing process. These two factors make the TC of the PS/PP/BN ternary composites increase sharply. Our strategy can potentially pave the way for the easy, low-cost and large-scale preparation of highly thermally conducive polymer-based composites as thermal management materials.