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Coatings 2017, 7(9), 138; https://doi.org/10.3390/coatings7090138

Thermal Transport on Graphene-Based Thin Films Prepared by Chemical Exfoliations from Carbon Nanotubes and Graphite Powders

Fujian Provincial Key Laboratory of Functional Materials and Applications, Institute of Material Preparation and Applied Technology, School of Materials Science and Engineering, Xiamen University of Technology, Xiamen 361024, China
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Received: 13 July 2017 / Revised: 30 August 2017 / Accepted: 31 August 2017 / Published: 3 September 2017
(This article belongs to the Special Issue Nanostructured Functional Coatings)
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Abstract

Thermal conductivities (k) of different graphene nanosheet (GN)-based heat sinks are investigated within the temperature range of 323–423 K. One- and two-step modified Hummers’ methods are adopted to chemically exfoliate GNs from two kinds of carbon precursors: carbon nanotubes (CNTs) and graphite powders. The two-step method offers an improved exfoliation level of GN products, especially for the CNT precursor. Experimental results show that the GN-based heat sink—exfoliated from graphite powders after the two-step approach—delivers an enhanced k value to 2507 W/m K at 323 K, as compared to the others. The k value is found to be a decreasing function of the porosity of the heat sink, revealing the importance of solid/void fraction (i.e., volumetric heat capacity). The improved thermal efficiency mainly originates from the long phonon mean free path and the low void fraction of GN-based heat sinks, thus inducing highly efficient thermal transport in the GN framework. View Full-Text
Keywords: graphene-based thin films; heat sink; thermal conductivity; carbon nanotubes; chemical exfoliation; graphite powders graphene-based thin films; heat sink; thermal conductivity; carbon nanotubes; chemical exfoliation; graphite powders
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Xie, J.-D.; Gu, S.-Y.; Zhang, H. Thermal Transport on Graphene-Based Thin Films Prepared by Chemical Exfoliations from Carbon Nanotubes and Graphite Powders. Coatings 2017, 7, 138.

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