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Fabrication and Resistivity of IBr Intercalated Vapor-Grown Carbon Fiber CompositesComposites using vapor-crown carbon fibers (VGCF), the most conductive of the carbon fiber types, are attractive for applications where low density, high strength, and at least moderate conductivity are required, such as electromagnetic interference shielding covers for spacecraft. The conductivity can be enhanced another order of magnitude by intercalation of the VGCF. If a high Z intercalate is used, the protection of components from ionizing radiation can be enhanced also. Thus, the intercalation of VGCF with IBr is reported. Since composite testing is required to verify properties, the intercalation reaction optimization, stability of the intercalation compound, scale-up of the intercalation reaction, composite fabrication, and resistivity of the resulting composites is also reported. The optimum conditions for low resistivity and uniformity for the scaled up reaction (20-30 g of product) were 114 C for at least 72 hr, yielding a fiber with a resistivity of 8.7+/-2 micro-Omega-cm. The thermal stability of these fibers was poor, with degradation occurring at temperatures as low as 40 C in air, though they were insensitive to water vapor. Composite resistivity was 20-30 micro-Omega-cm, as measured by contactless conductivity measurements, about a factor of five higher than would be expected from a simple rule of mixtures. The addition of 1.0 percent Br2, intercalated microfibers increased the resistivity of the composites by more than 20 percent.
Document ID
19990008957
Document Type
Technical Memorandum (TM)
Authors
Gaier, James R. (NASA Lewis Research Center Cleveland, OH United States)
Smith, Jaclyn M. (Manchester Coll. North Manchester, IN United States)
Gahl, Gregory K. (Manchester Coll. North Manchester, IN United States)
Stevens, Eric C. (Manchester Coll. North Manchester, IN United States)
Gaier, Elizabeth M. (Manchester Coll. North Manchester, IN United States)
Date Acquired
September 6, 2013
Publication Date
November 1, 1998
Subject Category
Composite Materials
Report/Patent Number
NASA/TM-1998-208493
E-11282
NAS 1.15:208493
Meeting Information
Composites Engineering(Las Vegas, NV)
Funding Number(s)
PROJECT: RTOP 632-1E-1E
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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