1. Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, Hunan, P. R. China
2. College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, Hunan, P. R. China
3. College of Materials Science and Engineering, Hunan University, Changsha 410082, Hunan, P. R. China
4. College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, Hunan, P. R. China