1 research outputs found
Continuous Carbon Nanotube-Based Fibers and Films for Applications Requiring Enhanced Heat Dissipation
The production of
continuous carbon nanotube (CNT) fibers and films
has paved the way to leverage the superior properties of individual
carbon nanotubes for novel macroscale applications such as electronic
cables and multifunctional composites. In this manuscript, we synthesize
fibers and films from CNT aerogels that are continuously grown by
floating catalyst chemical vapor deposition (FCCVD) and measure thermal
conductivity and natural convective heat transfer coefficient from
the fiber and film. To probe the mechanisms of heat transfer, we develop
a new, robust, steady-state thermal characterization technique that
enables measurement of the intrinsic fiber thermal conductivity and
the convective heat transfer coefficient from the fiber to the surrounding
air. The thermal conductivity of the as-prepared fiber ranges from
4.7 ± 0.3 to 28.0 ± 2.4 W m<sup>–1</sup> K<sup>–1</sup> and depends on fiber volume fraction and diameter. A simple nitric
acid treatment increases the thermal conductivity by as much as a
factor of ∼3 for the fibers and ∼6.7 for the thin films.
These acid-treated CNT materials demonstrate specific thermal conductivities
significantly higher than common metals with the same absolute thermal
conductivity, which means they are comparatively lightweight, thermally
conductive fibers and films. Beyond thermal conductivity, the acid
treatment enhances electrical conductivity by a factor of ∼2.3.
Further, the measured convective heat transfer coefficients range
from 25 to 200 W m<sup>–2</sup> K<sup>–1</sup> for all
fibers, which is higher than expected for macroscale materials and
demonstrates the impact of the nanoscale CNT features on convective
heat losses from the fibers. The measured thermal and electrical performance
demonstrates the promise for using these fibers and films in macroscale
applications requiring effective heat dissipation