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Electrical conductivity and rheology of carbon‐filled liquid crystal polymer composites
Author(s) -
King Julia A.,
Morrison Faith A.,
Keith Jason M.,
Miller Michael G.,
Smith Ryan C.,
Cruz Mariana,
Neuhalfen Amanda M.,
Barton Rodwick L.
Publication year - 2006
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.23914
Subject(s) - materials science , composite material , carbon black , graphite , percolation threshold , rheology , viscosity , composite number , electrical resistivity and conductivity , shear thinning , carbon fibers , percolation (cognitive psychology) , conductivity , volume fraction , chemistry , natural rubber , engineering , neuroscience , electrical engineering , biology
Abstract One emerging market for electrically conductive resins is for bipolar plates for use in fuel cells. Adding carbon fillers to thermoplastic resins increases composite electrical conductivity and viscosity. Current technology often adds as much of a single type of carbon filler as possible to achieve the desired conductivity, while still allowing the carbon‐filled thermoplastic matrix material to be extruded and molded into a bipolar plate. In this study, varying amounts of two different types of carbon, one carbon black and one synthetic graphite, were added to Vectra A950RX liquid crystal polymer. The resulting single filler composites were then tested for electrical conductivity and rheological properties. The electrical conductivity followed that typically seen in polymer composites with a percolation threshold at 4 vol % for carbon black and at 15 vol % for synthetic graphite. Over the range of shear rates studied, the viscosity followed a shear‐thinning power law model with power‐law exponent ( n − 1) = −0.5 for neat Vectra A950RX and ( n − 1) = −0.7 for highly filled composite materials. Viscosity increased with increasing filler volume fraction for all shear rates. The viscosity–enhancement effect was more rapid for the composites containing carbon black when compared with those containing synthetic graphite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2680–2688, 2006