1. Department of Materials Science and Engineering City University of Hong Kong 83 Tat Chee Avenue, Kowloon Hong Kong 999077 P. R. China
2. School of Advanced Materials and Nanotechnology Xidian University Xi'an 710071 P. R. China
3. National Engineering Research Center for Advanced Polymer Processing Technology Zhengzhou University Zhengzhou Henan 450002 P. R. China
4. Institute of Process Engineering Chinese Academy of Sciences Beijing P. R. China
5. Shenzhen Research Institute City University of Hong Kong Nanshan District Shenzhen 518057 P. R. China