Alignments and network of graphite fillers to improve thermal conductivity of epoxy-based composites. (October 2015)

• Record Type: Journal Article
• Authors: Burger, N.; Laachachi, A.; Mortazavi, B.; Ferriol, M.; Lutz, M.; Toniazzo, V.; Ruch, D.
• Is Part Of: International journal of heat and mass transfer. Volume 89(2015:Oct.)
• Page Start: 505
• Page End: 513
• Publication Date: 2015-10
• Subjects: Thermal conductivity -- Composites -- Alignment -- Network -- Epoxy; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2015.05.065
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Large inter-particles distances reduce thermal conductivity. Structured composites by networks or alignments of particles help increasing thermal conductivity. The more filler/matrix interfaces, the lower the thermal conductivity. 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.