Abstract
A weak thermal conductivity (TC) of a polymer can be modified by inclusion of nanoparticles with high TC. Here we study the TC enhancement in epoxy resin (ER) based composites by incorporation of carbon nanotubes (CNTs) and demonstrate that the enhancement depends critically on the alignment of CNTs. The highest effect in TC enhancement (18.9) was obtained in ER with vertically aligned multiwall CNTs (VANTs) and in ER with horizontally aligned nanotubes (HANTs) (6.5). We analyze the influence of intrinsic structural factors of CNTs as well as extrinsic factors limiting the enhancement of the composite TC. The dynamics of heat propagation in ER/VANT, a strongly anisotropic and heterogeneous system, was studied experimentally, using laser flash apparatus (LFA), and by computer simulation, applying a coaxial cylinder model. It was found that the thermal resistivity CNT-ER interface to be a key extrinsic factor limiting the dynamics of the heat propagation. We show that these dynamics and the interface resistivity can be efficiently studied using the LFA technique.
Highlights
More than 15 years have come since the very first estimations of thermal conductivity (TC) of carbon nanotubes (CNTs)
Molecular dynamic (MD) simulations predicted the maximum TC value can be as high as 37,500 W/(m·K) at T ≈ 100 K and decreased κ 6600 W/(m·K) at room temperature (RT) for isolated (10,10) single-walled CNTs (SWNTs) [1]
We report on the thermal conductivity measurements across the samples of epoxy resin (ER) with CNTs of different shapes and orientations, including vertically aligned (VANTs) and horizontally aligned (HANTs) MWNTs obtained by the permanent injection catalyst technique
Summary
More than 15 years have come since the very first estimations of thermal conductivity (TC) of carbon nanotubes (CNTs). Molecular dynamic (MD) simulations predicted the maximum TC value can be as high as 37,500 W/(m·K) at T ≈ 100 K and decreased κ 6600 W/(m·K) at room temperature (RT) for isolated (10,10) single-walled CNTs (SWNTs) [1]. The thermal conductivity of VANT film sandwiched between two glass plates was measured in a direct way in [16]. Taking into account the presence of a significant amount of porosity in the film, the value of κz was considered relatively high as compared with a single CNT
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