Effective thermal conductivity for nanocarbon/polyimide and carbon nanofiber/hexagonal boron nitride/polyimide composites

Effective thermal conductivity (TC) was experimentally measured for single‐walled carbon nanotube (SWCNT)/polyimide (PI) composites with a filler content up to 8 vol% and for carbon nanofiber (CNF)/PI composites with a filler content up to 24 vol%. The measurement results indicated that the values for effective TC for SWCNT/PI and CNF/PI composites were similar up to a filler content of 8 vol%. The experimental results were then correlated via thermal conductive models proposed by Xue and by Hamilton and Crosser, and reasonable correlation results were obtained for both the SWCNT/PI and CNF/PI composite sheets. The Nielsen model capably reproduced the experimental TC values without parameter‐fitting operations. Moreover, correlations using the effective medium approach (EMA) were also performed by adjusting the interfacial resistance. Good correlation results were obtained for both the SWCNT/PI and CNF/PI composites, and the correlated interfacial resistance showed reasonable values that compared to those found in the literature. Furthermore, the effect that the coadditions of CNF and hexagonal boron nitride (hBN) exerted on the effective TC of PI was investigated for a wide range of ratios of CNF to hBN. A small amount of CNF significantly increased the effective TC of CNF/hBN/PI composites. POLYM. COMPOS., 40:3032–3039, 2019. © 2018 Society of Plastics Engineers