Correlation between properties of coal-based mesophase pitch with sea-island texture prepared by hydrogenation and graphite fibers

Abstract

Refined coal tar pitch (RCTP) without pre-hydrogenation modification usually needs thermal sedimentation or centrifugation to obtain 100% coal-based mesophase pitch (CMP) after thermal polycondensation. This process is intricate and results in a low utilization rate of the overall pyrolysis products. Here, the sea-island texture CMP with mesophase content of more than 80% was directly prepared from RCTP by the co-carbonization method. Then, the practicality of this CMP was verified by the preparation of graphite fibers with high calculated thermal conductivity (1191W⋅m-1⋅K-1). The characterization results showed that 5 wt% tetrahydronaphthalene (THN) played the role of increasing the reactivity of pitch molecules, reducing the viscosity of the reaction system, increasing the mobility, and maintaining the molecules' planeness to a certain extent. Such effects were beneficial to the evolution of non-mesophase to mesophase molecules and its uniform dispersion in the mesophase, resulting in sea-island textures CMP with high anisotropy content. During the spinning process, the mesophase and non-mesophase molecules were oriented together, and they were further condensed to form larger carbon layers to obtain high thermal conductivity during high-temperature treatment. Therefore, this study is of great significance for the effective utilization of CMP and the preparation of high-value carbon materials.