Fibers 2018, 6(1), 3; https://doi.org/10.3390/fib6010003
Effect of Filler Orientation on the Electrical Conductivity of Carbon Fiber/PMMA Composites
1
Institute of Polymer Materials, Friedrich-Alexander-University Erlangen-Nuremberg, Martensstr. 7, 91058 Erlangen, Germany
2
School of Chemical Science and Engineering, Fibre and Polymer Technology, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
*
Authors to whom correspondence should be addressed.
Received: 17 November 2017 / Revised: 14 December 2017 / Accepted: 18 December 2017 / Published: 1 January 2018
(This article belongs to the Special Issue Carbon Fiber Reinforced Composites)
Abstract
The electrical conductivity of extruded carbon fiber (CF)/Polymethylmethacrylate (PMMA) composites with controlled CF aspect ratio and filler fractions ranging from 0 to 50 vol. % has been investigated and analyzed. The composites were extruded through a capillary rheometer, utilizing either 1-mm or 3-mm diameter extrusion dies, resulting in cylindrical composite filaments of two different diameters. Since the average CF orientation becomes more aligned with the extrusion flow when the diameter of the extrusion dies decreases, the relationship between conductivity and average fiber orientation could therefore be examined. The room temperature conductivities of the extruded filaments as a function of CF fractions were fitted to the McLachlan general effective medium (GEM) equation and the percolation thresholds were determined to 20.0 ± 2.5 vol. % and 32.0 ± 5.9 vol. % for the 3-mm (with CFs oriented less) and 1-mm (with CFs oriented more) filaments, respectively. It turned out that the oriented CFs in the composite shift the percolation threshold to a higher value, however, the conductivity above the percolation threshold is higher for composites with oriented CFs. A novel approach based on the Balberg excluded volume theory was proposed to explain this counterintuitive phenomenon. View Full-TextKeywords:
conductivity; carbon fibers; orientation; extrusion
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MDPI and ACS Style
Qu, M.; Nilsson, F.; Schubert, D.W. Effect of Filler Orientation on the Electrical Conductivity of Carbon Fiber/PMMA Composites. Fibers 2018, 6, 3.
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