Geometric analysis of enhanced thermal conductivity in epoxy composites: A comparison of graphite and carbon nanofiber fillers

Journal Article · Mon Sep 05 00:00:00 EDT 2016 · Physica Status Solidi. A, Applications and Materials Science

DOI:https://doi.org/10.1002/pssa.201600368· OSTI ID:1400582

Ruminski, Anne M. ^[1]; Yang, Fan ^[1]; Cho, Eun Seon ^[1]; Silber, Joseph ^[2]; Olivera, Edgar ^[1]; Johnson, Thomas ^[2]; Anderssen, Eric C. ^[2]; Haber, Carl H. ^[3]; Urban, Jeffrey J. ^[1]

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1. The Molecular Foundry, Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA
2. Engineering Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA
3. Physics Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA

We analyze the geometric effects of two different carbon fillers on the enhancement of the thermal conductivity of carbon‐epoxy composites. This study compares the thermal properties of composites containing graphite powder (2‐dimensional) and carbon nanofibers (1‐dimensional) incorporated in an industrial epoxy. Calculations using the generalized effective medium model were also used to examine the effect of the geometry and aspect ratio of the carbon filler. Experiments show that at a filler volume fraction loading of 0.10, the effective thermal conductivity of the composites was improved up to eightfold for carbon nanofiber and threefold for graphite in comparison to the neat epoxy. The superior performance of the carbon nanofiber composite is due to the larger aspect ratio of nanofiber which allows greater overlap between neighboring particles. However, this greater overlap also results in the composite becoming prohibitively viscous at low filler volume fractions. In graphite composite at the maximum filler volume fraction of 0.3, the resulting thermal conductivity improvement was 14‐fold over the neat epoxy. Calculations indicated that the improved thermal conductivity was primarily due to the filler particle geometry. Additionally, calculations suggest the wider distribution of graphite particle aspect ratio could have a positive influence on enhancing composite thermal conductivity.

• Sponsoring Organization: USDOE
• OSTI ID: 1400582
• Journal Information: Physica Status Solidi. A, Applications and Materials Science, Journal Name: Physica Status Solidi. A, Applications and Materials Science Vol. 214 Journal Issue: 1; ISSN 1862-6300
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: Germany
• Language: English