Thermal management at structural interfaces operating in high thermal environments have initiated a demand for high performance load-bearing thermal interface materials (TIMs). This paper reports development of vertically aligned multi-wall carbon nanotube (VA MWCNT) array composites for thermal energy management in load-bearing structural applications. The material systems of interest here involve the use of VA MWCNTs in an epoxy matrix. The epoxy matrix imparts mechanical strength to these systems while the MWCNTs provide avenues for high thru-thickness thermal conductivity across a typical material interface. In order to obtain the thermal characteristics of these multifunctional TIMs, we report measurements of thermal conductivity in Sn- capped VA-MWCNT-epoxy composites as well as in its individual constituents in the temperature range 240 K 300 K, and individual multi-wall carbon nanotubes at room temperature taken from the same VA-MWCNT batch as the one used to fabricate the CNT-epoxy TIM. The thermal conductivity of the epoxy and Sn thin film was obtained as a function of temperature by using a cryostat in conjunction with the three omega method. The thermal conductivity of individual free standing MWCNT samples was obtained by employing the Wollaston T-type three-omega probe method inside a high resolution scanning electron microscope. The results of this study suggests that the inclusion of a Sn thin layer on the VA-MWCNT array, as well as the morphological structure of the individual MWCNT s are dominating factors that control the overall thermal conductivity of the TIM. These results are encouraging in light of the fact that the thermal conductivity of a VA-MWCNT array can be increased by an order of magnitude by using a standard high-temperature post-annealing step. In this way, multifunctional (load bearing) TIMs with effective through thickness thermal conductivities as high as 25 W/m-K, can be potentially fabricated.
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