Significantly enhancing the through-plane thermal conductivity of epoxy dielectrics by constructing aramid nanofiber/boron nitride three-dimensional interconnected framework

• Published in: Journal of applied physics 2024-07, Vol.136 (4)
• Main Authors: Ren, Jun-Wen, Zeng, Rui-Chi, Yang, Jun, Wang, Zi, Wang, Zhong, Zhao, Li-Hua, Wang, Guo-Long, Jia, Shen-Li
• Format: Article
• Language: English
• Subjects: Boron nitride; Dielectric loss; Heat conductivity; Heat transfer; Nanofibers; Thermal conductivity; Thermal management
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/5.0211580

Epoxy dielectrics with high through-plane thermal conductivity (λ) hold great promise for applications in the thermal management of advanced power electronics. Intensive attempts have been made to improve the λ of epoxy by filling with boron nitride nanosheets (BNNSs). However, it remains a great challenge to achieve a satisfactory increased λ by a small amount of BNNS loading. Herein, we reported a new strategy to prepare epoxy dielectrics with internal three-dimensional phonon transport channels by vacuum freeze-drying and vacuum impregnation. Aramid nanofibers (ANFs) and BNNSs were used for the collaborative construction of a vertical interconnected thermal framework. The resultant ANF-BNNS/epoxy achieved a high through-plane λ of 0.87 W m−1 K−1 at only 1.43 vol. % BNNS, which is ∼17.1% higher than that of the BNNS/epoxy counterpart with even 18.34 vol. % randomly distributed BNNS. The increasing efficiency of λ of epoxy by ANF-BNNS is tenfold more than that of the conventional blending methods. In addition, the ANF-BNNS/epoxy composite also exhibits a low dielectric constant and low dielectric loss. The findings of this study offer an inspired venue to develop high-performance thermally conductive epoxy dielectrics with a minimal BNNS loading.