沥青原料对沥青基碳纤维结构与性能的影响

Effects of raw materials on structure and properties of pitch-based carbon fibers

以中间相萘沥青(AR树脂)和各向同性煤沥青(ICP)为原料,系统研究了沥青原料性质与由其制备的碳纤维结构、性能之间的关系。研究表明,AR树脂中的一维有序中间相结构在纺丝中被拉伸,形成不同中间相间的界面,成为应力集中区,在后续碳化过程因应力释放导致纤维开裂而损害其力学性能;而ICP沥青基本为无定形相结构,在纺丝过程中无明显的择优取向,碳化过程石墨化程度低,故其所成的碳纤维无应力集中和开裂问题,但也正是这无定形结构,使其最终力学性能也较差。以上结果说明,原料的性质可以"遗传"到沥青基碳纤维中。因此,改变沥青原料的性质是改善沥青基碳纤维结构和性能的有效途径之一。

In this paper,naphthalene mesophase pitch（AR resin） and isotropic coal tar pitch（ICP） were employed as raw materials to prepare carbon fibers.Effects of raw materials on the structure and properties of the resultant carbon fibers were systematically investigated.Results show that the one-dimensionally ordered mesophase structure in AR resin was elongated along the fiber axis during melt spinning,and interfaces were formed between mesophase domains,resulting in stress concentration in these regions.The stress was released in the process of carbonization,and the formed cracks had adverse effects on the mechanical properties of the carbon fibers.In contrast,ICP was free of the ordered structure and hence no preferred orientation formed in the process of melt spinning,and no stress concentration regions and no cracking occurred during carbonization.The amorphous nature made ICP-based carbon fibers poorly graphitized and brought in low mechanical properties.These results show that the nature of pitch has profound effects in the final carbon fibers.Therefore,adjusting nature of the raw materials is an effective way to improve the structure and properties of pitch based-carbon fibers.