Preparation of pitch precursor with excellent spinnability for general-purpose carbon fibre using coal tar pitch as raw material

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Tetrahydrofuran (THF) extract of coal tar pitch (CTP) was used instead of blending CTP with pretreated pyrolysis fuel oil to prepare an isotropic pitch precursor with excellent spinnability for general-purpose carbon fibre through bromination–dehydrobromination. The feasibility and effectiveness of synthesising an isotropic pitch precursor derived from THF-soluble (CTP-THFs) is demonstrated in this study. The results show that CTP-THFs contains more light components than CTP; CTP-THFs and CTP monomer proportions were 62.52% and 45.32%, respectively. However, based on comparisons of CTP-THFsBr0 and CTPBr0 characterisations, CTP-THFs exhibits better polycondensation than CTP. Bromination–dehydrobromination promotes polycondensation of pitch precursors, leading to greater carbon aromaticity in CTP-THFsBr5, CTP-THFsBr10, and CTP-THFsBr15 than that in CTP-THFsBr0 and CTPBr0. CTP-THFsBr5 and CTP-THFsBr10 have excellent spinnability even with softening points as high as 230 °C. The peri-condensed carbon and carbon aromaticity of CTP-THFsBr5 and CTP-THFsBr10 are high owing to the higher degree of polycondensation; however, they still possess a more linear molecular structure. The as-prepared carbon fibre exhibits homogeneity and uniformity, and the mechanical performance is comparable with that of commercial general-purpose carbon fibre products.