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Thermal Diffusivity of Hexagonal Boron Nitride Composites Based on Cross-Linked Liquid Crystalline Polyimides
journal contribution
posted on 2013-04-24, 00:00 authored by Yu Shoji, Tomoya Higashihara, Masatoshi Tokita, Junko Morikawa, Junji Watanabe, Mitsuru UedaHexagonal boron nitride (h-BN) composites
with the oriented cross-linked liquid crystalline (LC) polyimide have
been developed as high thermally conductive materials. Well-dispersed
h-BN composite films were obtained, as observed by scanning electron
microscopy. The morphology of the composite films was further investigated
in detail by the wide-angle X-ray diffraction. The obtained composite
films based on the cross-linked LC polyimide showed that the polymer
chains vertically aligned in the direction parallel to the films,
while those based on the amorphous polyimide showed an isotropic nature.
Moreover, the alignment of the cross-linked LC polyimides was maintained,
even after increasing the volume fraction of h-BN. This alignment
plays an important role in the effective phonon conduction between
h-BN and the matrices. Indeed, the thermal diffusivity in the thickness
direction of the composite films based on the LC polyimide measured
by a temperature wave analysis method was increased to 0.679 mm2 s–1 at a 30 vol % h-BN loading, which was
higher than that based on the amorphous polyimide.