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Alignments and network of graphite fillers to improve thermal conductivity of epoxy-based composites.

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Title: Alignments and network of graphite fillers to improve thermal conductivity of epoxy-based composites.
Authors: Burger, N.1,2 nicolas.burger@list.lu, Laachachi, A.1, Mortazavi, B.3, Ferriol, M.2, Lutz, M.4, Toniazzo, V.1, Ruch, D.1
Source: International Journal of Heat & Mass Transfer. Oct2015, Vol. 89, p505-513. 9p.
Subjects: Graphite, Thermal conductivity, Epoxy resins, Filler materials, Nanocomposite materials
Abstract: Instead of improving the fillers dispersion in the matrix, some fillers alignments and structured composites were investigated in order to highlight their impact on thermal conductivity. Whereas well dispersed graphite-nanocomposites show some limit to reach high thermal conductivity values (0.84 W m −1 K −1 at 12 wt.%), 3D-structured composite or Z-pinning samples display much better enhancements of apparent thermal conductivity, reaching 2.1 W m −1 K −1 at 15 wt.%. Impact of insulating DGEBA interfaces was also investigated in this work. It was demonstrated that only two 4 μm-DGEBA layers cutting the fibers alignment is enough to bring thermal conductivity back to the value of the non-structured nanocomposite, losing all the positive impact of alignment. Mathematical evaluations helped estimating the through-plane thermal conductivities of the samples, highlighting the negative impact of interfaces, and displaying the major difference between a 3D-network sample and a Z-pinned aligned sample. Whereas the 3D-network sample displays a relatively good improvement of both in-plane and through-plane thermal conductivities, the Z-pinned sample presents a considerable increase of the through-plane thermal conductivity (until 6.8 W m −1 K −1 ), but also a negligible effect on the in-plane thermal conductivity. Resulting apparent thermal conductivities of both samples are finally quite comparable and more than doubled compared to non-structured nanocomposites. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
Description
Abstract:Instead of improving the fillers dispersion in the matrix, some fillers alignments and structured composites were investigated in order to highlight their impact on thermal conductivity. Whereas well dispersed graphite-nanocomposites show some limit to reach high thermal conductivity values (0.84 W m −1 K −1 at 12 wt.%), 3D-structured composite or Z-pinning samples display much better enhancements of apparent thermal conductivity, reaching 2.1 W m −1 K −1 at 15 wt.%. Impact of insulating DGEBA interfaces was also investigated in this work. It was demonstrated that only two 4 μm-DGEBA layers cutting the fibers alignment is enough to bring thermal conductivity back to the value of the non-structured nanocomposite, losing all the positive impact of alignment. Mathematical evaluations helped estimating the through-plane thermal conductivities of the samples, highlighting the negative impact of interfaces, and displaying the major difference between a 3D-network sample and a Z-pinned aligned sample. Whereas the 3D-network sample displays a relatively good improvement of both in-plane and through-plane thermal conductivities, the Z-pinned sample presents a considerable increase of the through-plane thermal conductivity (until 6.8 W m −1 K −1 ), but also a negligible effect on the in-plane thermal conductivity. Resulting apparent thermal conductivities of both samples are finally quite comparable and more than doubled compared to non-structured nanocomposites. [ABSTRACT FROM AUTHOR]
ISSN:00179310
DOI:10.1016/j.ijheatmasstransfer.2015.05.065