2D SAXS/WAXD ANALYSIS OF PAN CARBON FIBER MICROSTRUCTURE IN ORGANIC/INORGANIC TRANSFORMATION  

作　　者：Cai-zhen Zhu Xiao-lan Yu Xiao-fang Liu Yun-zen Mao Rui-gang Liu 赵宁 Xiao-li Zhang 徐坚 

机构地区：[1]Beijing National Laboratory for Molecular Sciences,Laboratory of Polymer Physics and Chemistry,Institute of Chemistry,Chinese Academy of Sciences [2]ShenZhen Key Laboratory of Functional Polymer,College of Chemistry and Chemical Engineering,Shenzhen University [3]College of Materials Science and Engineering,Donghua University

出　　处：《Chinese Journal of Polymer Science》2013年第5期823-832,共10页高分子科学（英文版）

基　　金：financially supported by Innovation Method Fund of China(2011IM030400);NSFC(No.10835008);the Knowledge Innovation Project of CAS(No.KJCX2-YW-N39);973 Program(No.2011CB605604);the Opening Foundation of Shenzhen Key Laboratory of Functional Polymers(FP20120012);Natural Science Foundation of Shenzhen University(Grant no.201204);the Shenzhen basic research project(JCYJ20120614085820810)

摘　　要：Structure of PAN fibers during pre-oxidation and carbonization was studied using two dimensional small angle X-ray scattering/wide angle X-ray diffraction （2D SAXS/WAXD）. The SAXS results show that during pre-oxidation between 180 ℃ and 275 ℃, the volume content of microvoids increases with the temperature increasing, which may be one of reasons for the decrease of tensile strength ofpre-oxidized fibers. 253 ℃ was the critical transition temperature, the length, diameter, aspect ratio and orientation distribution of microvoids increased with temperature before this temperature and decreased after this temperature. After the high temperature carbonization, lots of spindly microvoids formed. WAXD patterns demonstrate that the crystallite size of PAN fibers first increased before 230 ℃ and then decreased with the increase of temperature during the pre-oxidation. The diffraction peak of PAN fibers at 2θ ≈ 17°almost disappeared at the end of pre- oxidation while the diffraction peak of aromatic structure at 2θ ≈ 25° appeared at 253 ℃. During carbonization, the peak intensity at 2θ ≈ 25° increased apparently due to the formation of graphite structure. The results obtained give a deep understanding of the microstrncture development in the PAN fibers during pre-oxidation and carbonization, which is important for the preparation of high performance carbon fibers.Structure of PAN fibers during pre-oxidation and carbonization was studied using two dimensional small angle X-ray scattering/wide angle X-ray diffraction （2D SAXS/WAXD）. The SAXS results show that during pre-oxidation between 180 ℃ and 275 ℃, the volume content of microvoids increases with the temperature increasing, which may be one of reasons for the decrease of tensile strength ofpre-oxidized fibers. 253 ℃ was the critical transition temperature, the length, diameter, aspect ratio and orientation distribution of microvoids increased with temperature before this temperature and decreased after this temperature. After the high temperature carbonization, lots of spindly microvoids formed. WAXD patterns demonstrate that the crystallite size of PAN fibers first increased before 230 ℃ and then decreased with the increase of temperature during the pre-oxidation. The diffraction peak of PAN fibers at 2θ ≈ 17°almost disappeared at the end of pre- oxidation while the diffraction peak of aromatic structure at 2θ ≈ 25° appeared at 253 ℃. During carbonization, the peak intensity at 2θ ≈ 25° increased apparently due to the formation of graphite structure. The results obtained give a deep understanding of the microstrncture development in the PAN fibers during pre-oxidation and carbonization, which is important for the preparation of high performance carbon fibers.

关 键 词：POLYACRYLONITRILE PRE-OXIDATION Carbonization SAXS/WAXD Microstructure. 

分 类 号：TQ342.742[化学工程—化纤工业] O632.61[理学—高分子化学]