Electrical conductivity and Joule heating of polyacrylonitrile/carbon nanotube composite fibers

• Published in: Polymer (Guilford) 2014-12, Vol.55 (26), p.6896-6905
• Main Authors: Chien, An-Ting, Cho, Sangbeom, Joshi, Yogendra, Kumar, Satish
• Format: Article
• Language: English
• Subjects: Applied sciences; Carbon nanotube; Carbon nanotubes; Composite fibers; Composites; Electrical conductivity; Electrical resistivity; Exact sciences and technology; Fibers; Forms of application and semi-finished materials; Joule heating; Mathematical analysis; Polyacrylonitriles; Polymer industry, paints, wood; Resistivity; Technology of polymers
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2014.10.064

Carbon nanotube (CNT) can exhibit electrical conductivity and introduce electric current into polymer. Using dry-jet-wet spin technology, polyacrylonitrile (PAN)/CNT composite fibers with 15 wt% and 20 wt% of CNT content were fabricated. The electrical conductivity of PAN/CNT fibers was enhanced by the annealing process at different temperatures and changed with time. These fibers could also respond to stretching, and the electrical conductivity decreased by 50% when the elongation reached 3%. In addition, electrical current can induce Joule heating effect and thermally transform PAN/CNT composite fibers. With the application of various electrical currents up to 7 mA at a fixed length, conductivity was enhanced from around 25 S/m to higher than 800 S/m, and composite fibers were stabilized in air. The temperature of composite fibers can increase from room temperature to several hundreds of degree Celsius measured by an infra-red (IR) microscope. Joule heating effect can also be estimated according to one-dimensional steady-state heat transfer equation, which reveals the temperature can be high enough to stabilize or carbonize fibers. As a result, this research provides a new idea of heating fabrics for thermal regulation, and a new approach for stabilizing and carbonizing PAN-based carbon fibers. [Display omitted] •Annealing of PAN/CNT composite fibers results in re-arrangement of CNT network and enhanced electrical conductivity.•The electrical conductivity of the composite fibers is a function of elongation.•Joule heating can increase the fiber temperature to 1000 °C, as estimated by the one-dimensional steady-state heat transfer equation.•Joule heating can enhance electrical conductivity from 25 S/m to higher than 800 S/m•With the application of electrical current, PAN/CNT composite fibers can be stabilized and carbonized.