Self-sintering mechanism of stabilising mesophase pitch fibres

Abstract

The ribbon mesophase pitch fibres (MPFs) can be sintered into bulk graphite materials with high thermal conductivity by one-step hot pressing method without introducing any binder. The contents of elements and group compositions as well as oxygenic functional groups of MPFs with different oxidation degrees were investigated by means of group composition analysis, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Then, the self-sintering mechanisms of the MPFs with different oxidation degrees were discussed in terms of their sintering ability and the influences on the structural performances of target materials. The results show that the fibres oxidised moderately have appropriate amount of phenol hydroxyl and carboxyl on their surface, which are beneficial to self-sintering. Meanwhile, the axial preferred orientation of aromatic macromolecules obtained during melt spinning can be maintained in fibre under a high temperature. For example, the materials, self-sintered from the ribbon MPFs oxidised at 260°C, have a thermal conductivity of 609 W m−1 K and a bending strength of 126 MPa.