This letter reports on fast and highly anisotropic thermal transport through millimeter-tall,
vertically aligned carbon nanotube arrays (VANTAs) synthesized by chemical vapor
deposition on Si substrates. Thermal diffusivity measurements were performed for both
longitudinal and transverse to the nanotube alignment direction, with longitudinal values as
large as 2.1±0.2 cm 2∕ s and anisotropy ratios as large as 72. Longitudinal thermal
conductivities of 15.3±1.8 W∕(m K) for porous 8±1 vol% VANTAs in air and 5.5±0.7 W∕(m …