Title: Quantitative appraisal of the interfacial anchoring state of polyaromatic hydrocarbons during the formation of C/C composites
Authors: Lin, Cheng-Te
Tsai, Min-Chiao
Lee, Chi-Young
Chiu, Hsin-Tien
Chin, Tsung-Shune
Department of Applied Chemistry
Issue Date: 1-Apr-2010
Abstract: The preferred anchoring state for polycyclic aromatic hydrocarbons (PAHs) pyrolyzed onto carbon substrates has been studied by semi-quantitative methods, examining their interfacial lattice arrangements. The samples were prepared by decomposing petroleum pitch inside carbon nanotubes resulting in a variety of crystallinities forming one-dimensional C/C composites. Studies indicate that the preferred anchoring state of PAH molecules depends on the nature of the substrate. Accordingly the PAHs in mesophase pitch should exhibit a face-on orientation on the carbonaceous substrates, including a graphite sheet, glassy carbon, and pyrolytic carbon. However, it showed that the anchoring state (face-on or edge-on) of PAH units can be altered even on carbonaceous substrates. The results demonstrated that in C/C composites the anchoring state is predominantly determined by the relative degree of crystallinity of the pitch/carbon substrate, and can be semi-quantitatively estimated using the I(D)/I(G) ratio from Raman spectra. Face-on anchoring is preferred when the I(D)/I(G); ratio of substrate is smaller (higher crystallinity) than that of the pyrolyzed precursor, whereas edge-on anchoring is favored when it is larger. Such an estimation method is useful in tailoring microstructures in the fabrication of C/C composites using PAH precursors. (C) 2009 Elsevier Ltd. All rights reserved.
URI: http://dx.doi.org/10.1016/j.carbon.2009.11.024
ISSN: 0008-6223
DOI: 10.1016/j.carbon.2009.11.024
Journal: CARBON
Volume: 48
Issue: 4
Begin Page: 1049
End Page: 1055
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