Anisotropic thermal and electrical conductivities of individual polyacrylonitrile-based carbon fibers

Understanding the anisotropy of thermal and electrical properties carbon fibers is important for many applications, but transverse transport are difficult to measure. We apply time-domain thermoreflectance (TDTR) mapping determine spatial variations in conductivity different radial positions two polyacrylonitrile (PAN)-based fibers, IM7 AS4 fibers. Single-point TDTR measurements longitudinal conductivities The resistivities determined by van der Pauw method four-point method, respectively. approximately uniform (2.0 W/m-K) at positions. In contrast, core (3.0 higher than shell (2.4 W/m-K). 7.5 W/m-K value 6.9 W/m-K. resistivity 6.3 × 10−5 Ωm 1.5 Ωm; were reported previously. Both indicate a larger fiber fiber.