PAN基炭纤维径向结构高温演变机制及其与力学性能的关系  

High temperature evolution of the microstructure in the radial direction of PAN-based carbon fibers and its relationship to mechanical properties

作　　者：阮如玉 叶联葳 冯海 徐樑华 王宇[1,2] RUAN Ru-yu;YE Lian-wei;FENG Hai;XU Liang-hua;WANG Yu(National Carbon Fiber Engineering Research Center,Beijng 100029,China;Beijing University of Chemical Technology,Beijing 100029,China)

机构地区：[1]国家碳纤维工程技术研究中心,北京100029 [2]北京化工大学,北京100029

出　　处：《新型炭材料》2020年第3期295-306,共12页New Carbon Materials

基　　金：装备预研教育部联合基金(6141A02033231,6141A02033223);国防基础科研计划(JCKY2018110C139);中央高校基本科研业务费基地项目(JD1907).

摘　　要：为了研究高温处理条件下炭纤维径向结构的演变规律及其对力学性能的影响,采用Raman光谱仪、元素分析仪、X射线衍射仪、高分辨透射电子显微镜、原子力显微镜和力学性能测试仪等表征方法,系统地对不同温度处理后的炭纤维进行结构解析。结果表明,由于纤维在高温处理过程中热解与重组同时发生,炭纤维径向结构的变化可分为两个阶段。第一阶段为处理温度低于1700℃时的径向结构差异随处理温度升高而减小的阶段,此阶段热裂解对径向结构差异的影响起主导作用。第二阶段为处理温度高于1700℃的径向结构差异随处理温度升高而增大的阶段,此阶段结构重组对径向结构差异的影响起主导作用。受径向结构差异的影响,炭纤维拉伸强度随处理温度的升高,呈现先增大后减小的趋势,经1700℃处理后的炭纤维径向结构趋于均质,拉伸强度达到最大。依据炭纤维石墨化程度与炭微晶大小的关系,炭纤维皮层炭微晶为纤维径向上最规整、最完整的碳结构,因此炭纤维拉伸模量主要取决于皮层大尺寸且高取向的炭微晶。The radial microstructural in carbon fibers is important for their mechanical properties.Microstructures at different locations in the radial direction produced by heat treatments from 1350 to 2400℃and their relationship to the mechanical properties were investigated by Raman spectroscopy,elemental analysis,X-ray diffraction,high-resolution transmission electron microscopy and mechanical testing.Results indicated that the differences of the shift and full widths at half maxima(FWHM)of the Raman G and D bands at different points in the radial direction from the skin to the core,show ed minima while the tensile strength of the fibers was a maximum at 1700℃heat treatment temperature.The maximum tensile strength of carbon fibers at 1700℃ was ascribed to the smallest skin-core variation at this temperature.The FWHM of the G and D bands from the same points in the radial direction decreased with heat treatment temperature,indicating an increased uniformity of the vibration modes of both G and D bands The sizes and the orientation degree of the crystallites increased with heat treatment temperature,leading to an increase of tensile modulus.Non-carbon elements were preferentially released,and crystallites were preferentially grow n and orientated in the skin region compared to those in the core due to the preferential heat absorption in the skin,leading to the low er values of FWHM of G and D bands in the skin than in the core.The Raman shift of the G band had a maximum at 1700℃ while that of D band decreased with heat treatment temperature at the same radial points of the fibers.The fact that the release rate of non-carbon elements increased with heat treatment temperature below 1700℃could be responsible for the increased G band shift below 1700℃.With a continuous decrease in the non-carbon element content,this effect was lessened and the improvement of the perfection of the graphite structure became dominant above 1700℃.

关 键 词：PAN基炭纤维 径向结构 热解 重组 力学性能 

分 类 号：TQ342.[化学工程—化纤工业]