1. CAS Key Laboratory for Carbon Materials Institute of Coal Chemistry Chinese Academy of Sciences Taiyuan 030001 P. R. China
2. National Engineering Laboratory for Carbon Fiber Technology Institute of Coal Chemistry Chinese Academy of Sciences Taiyuan 030001 P. R. China
3. Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Beijing 100049 P. R. China
4. Yangzhou Engineering Research center of Carbon Fiber Institute of Coal Chemistry Chinese Academy of Sciences Yangzhou 225131 P. R. China