The excellent mechanical properties and thermal conductivity of mesophase pitch-based carbon fibers are intricately linked to the rheological properties and molecular structure of mesophase pitch (MP). In this study, spinnable mesophase pitch was prepared through hydrogenation and thermal condensation, and the impact of refined coal tar pitch (RCTP) hydrogenation on the rheological properties and molecular structure of MP was investigated. Molecular structure characterization results of hydrogenated pitch (HP) showed a significant increase in aliphatic chain structure, naphthenic structure, and methylene structure, along with an elevated H/C atomic ratio ranging from 0.602 to 0.700 with an increase in hydrogenation degree. The rheological and spinning properties of MP were assessed using a capillary rheometer, high-temperature rotational rheometer, melt spinning machine and other equipment. Results indicated a lower viscosity and softening point of MP, improved fluidity, and enhanced spinning stability with increasing hydrogenation degree. Polarizing microscope, X-ray diffraction， and Raman spectroscopy were used to characterize the molecular structure of MP. Findings emphasized that an optimal degree of hydrogenation facilitated the formation of a large domain structure and orderly stacking of MP molecules, maintaining molecular planarity to a certain extent. Excessive hydrogenation of RCTP, however, led to a reduction in the degree of order in the molecular arrangement of MP. When the H/C atomic ratio of HP ranged from 0.648 to 0.669, a notable reduction in MP system viscosity, improved spinning stability, and maintained molecular planarity were observed. During the spinning process, favorable rheology and planarity promoted the orderly arrangement of MP aromatic planar molecules along the tensile direction. This holds significant implications for preparing mesophase pitch-based carbon fiber with excellent mechanical properties and thermal conductivity.

中文翻译：

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加氢程度对煤基可纺中间相沥青性能的影响


中间相沥青基碳纤维优异的机械性能和导热性与中间相沥青（MP）的流变性能和分子结构密切相关。本研究通过加氢和热缩合制备了可纺中间相沥青，并研究了精制煤焦油沥青（RCTP）加氢对MP流变性能和分子结构的影响。氢化沥青(HP)的分子结构表征结果显示，随着氢化程度的增加，脂肪链结构、环烷结构和亚甲基结构显着增加，H/C原子比也随之增加，范围从0.602到0.700。使用毛细管流变仪、高温旋转流变仪、熔体纺丝机等设备对MP的流变和纺丝性能进行了评估。结果表明，随着氢化程度的增加，MP 的粘度和软化点降低，流动性提高，纺丝稳定性增强。利用偏光显微镜、X射线衍射和拉曼光谱对MP的分子结构进行了表征。研究结果强调，最佳的氢化程度有利于MP分子形成大域结构和有序堆叠，在一定程度上保持分子平面性。然而，RCTP的过度氢化导致MP分子排列的有序度降低。当HP的H/C原子比在0.648至0.669范围内时，观察到MP体系粘度显着降低，纺丝稳定性提高并保持分子平面性。 在纺丝过程中，良好的流变性和平面性促进了MP芳族平面分子沿拉伸方向的有序排列。这对于制备具有优异机械性能和导热性的中间相沥青基碳纤维具有重要意义。