Thermal Diffusivity of Hexagonal Boron Nitride Composites Based on Cross-Linked Liquid Crystalline Polyimides

Abstract

Hexagonal 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 mm(2) s(-1) at a 30 vol % h-BN loading, which was higher than that based on the amorphous polyimide.

Enhanced thermal conductivity in immiscible polyimide blend composites with needle-shaped ZnO particles

“…7(b)). 24 The diffraction images of the composite lms are presented in Fig. 7(c), which shows diffraction peaks assignable to (100), (002), (101), (102), (110) and (103) diffraction.…”

Boron Nitride Nanomaterials for Thermal Management Applications

“…The effect of polymeric matrices and their orientations on the thermal transport performance of the composites with BNNs have also been considered 74. 75 For example, in the work by Shoji et al,74 oriented cross‐linked liquid‐crystalline polyimide was used as a matrix for thermally conductive composites with BNNs.…”

“…The effect of polymeric matrices and their orientations on the thermal transport performance of the composites with BNNs have also been considered 74. 75 For example, in the work by Shoji et al,74 oriented cross‐linked liquid‐crystalline polyimide was used as a matrix for thermally conductive composites with BNNs. The observed thermal diffusivity in these composites was in the order of 0.68 mm 2 s −1 at a 30 vol % h‐BN loading, which was somewhat higher (about 10 %) than that in the composites made with amorphous polyimide 74.…”

“…75 For example, in the work by Shoji et al,74 oriented cross‐linked liquid‐crystalline polyimide was used as a matrix for thermally conductive composites with BNNs. The observed thermal diffusivity in these composites was in the order of 0.68 mm 2 s −1 at a 30 vol % h‐BN loading, which was somewhat higher (about 10 %) than that in the composites made with amorphous polyimide 74. The increasing amount of BNNs in the composites apparently had no significant impact on the orientation order of the cross‐linked liquid‐crystalline chains.…”

Boron nitride nanotubes and nanoplatelets as reinforcing agents of polymeric matrices for bone tissue engineering

“…[18][19][20] The mechanical properties of their nanocomposites is enhanced by various functional groups such as amines, nitriles, epoxides, and oxides [21][22][23] due to improvement in their dispersion in polymer matrices that facilitate better polymer-nanomaterial interaction and allow efficient load transfer from the polymer to the nanomaterial. 19 Additionally, it has been reported that presence of boron nitride nanomaterials (specifically exfoliated boron nitride nanosheets 24 ) improves the thermal conductivity of polymers, and therefore, may be beneficial for in situ thermal crosslinking of injectable polymer mixtures.…”