21st International Conference on Composite Materials, ICCM 2017, Xian, China, 20 - 25 August 2017, vol.2017-August
© 2017 International Committee on Composite Materials. All rights reserved.Two-dimensional (2D) materials have aroused remarkable attention since the successful separation of graphene, atomic layers of carbon, has demonstrated novel electronic properties. Boron nitride (BN) is a structural analog of carbon. BN can be exfoliated to form unique 2D crystal structures called boron nitride nanosheets (BNNSs). BNNSs are believed to have potential to find applications in heat-releasing composite materials, since they are electrically insulating, besides being as thermally conductive and mechanically robust as graphene. In this study, a microfluidizer, high pressure fluid processor, was conducted for the first time to exfoliate few layer two dimensional (2D) boron nitride nanosheets (BNNSs) from micro-sized hexagonal boron nitride (h-BN) precursors of large flakes. The mixture of N, N-dimethyl formamide and chloroform was conducted as solvent. Secondary electron-scanning electron microscopy (SE-SEM) imaging, bright field-transmission electron microscopy (BF-TEM) imaging, energy filtering (EF) TEM-3 window elemental mapping, electron energy loss spectroscopy (EELS), high resolution (HR) TEM imaging and nano beam electron diffraction (NBED) techniques were carried out to characterize the sheets. Based on the findings obtained, the sheets were observed to have micrometer dimensions through in-plane, whereas nanometer dimensions through their thickness directions. Carbon fabric preforms containing 1 wt. % of BNNSs were then consolidated by dispersing the sheets in ethanol through sonication. The solution obtained was then used for through-the-thickness impregnation of carbon fabrics. The composites with BNNSs were then produced by membrane added vacuum infusion process (MAVIP) with application of mechanical vibrations at various different low frequencies, including 10, 25 and 60 Hz. For the sake of property comparison, identical static samples were also produced. A facile thermogravimetric analysis (TGA) based methodology was utilized for composite fiber volume fraction and void content measurements. Analysis was carried out on specimen-by-specimen basis, and the findings obtained were correlated with the interlaminar shear strength (ILSS) of the composites.