The influence of boron nitride shape and size on thermal conductivity, rheological and passive cooling properties of polyethylene composites

The shape and particle size of the filler are highly relevant to the composite's performance and application. We herein report the role of boron nitride (BN) shapes and sizes for polyethylene composites on the rheological properties, thermal conductivity (TC) and passive cooling via melt blending. Fillers with large sizes are adverse to form a rheological network in the composites, but they are beneficial to high thermal conductivity and their maximum increase (1.535 Wm(-1)K(-1)) relative to the matrix is 256%. Additionally, due to the high solar reflectance (90%) and thermal emittance (85%), the composites endow a cooling performance of 4 ? at daytime and 10 ? at night compared to the contrast temperature in the device. This work is helpful to provide guidance for the optimization of BN fillers for applications in the fields of thermal management and passive cooling.

Automated summary

The shape and particle size of the filler play a crucial role in determining the performance of composite materials. In this study, the effects of boron nitride (BN) shapes and sizes on the rheological properties, thermal conductivity, and passive cooling of polyethylene composites were investigated. Large-sized fillers negatively influenced the formation of a rheological network in the composites, but positively affected the thermal conductivity with a maximum increase of 256% compared to the matrix. Additionally, the composites exhibited excellent cooling performance due to their high solar reflectance and thermal emittance. This research provides valuable guidance for the optimization of BN fillers in thermal management and passive cooling applications.