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A comparative study on the preparation and characterization of cellulose nanocrystals with various polymorphs
- Gong, Jie, Mo, Lihuan, Li, Jun
- Carbohydrate polymers 2018 v.195 pp. 18-28
- acid hydrolysis, cellulose, comparative study, crystal structure, ethylenediamines, mercerization, nanocrystals, sodium hydroxide, sulfuric acid, thermal stability
- Polymorphic changes of cellulose nanocrystals (CNCs) are strongly associated with its properties and applications. In this study, CNCs with different polymorphs were produced by a simple polymorphic transformation treatment. Cellulose I nanocrystals were produced by typical sulfuric acid hydrolysis (CNC-I). Cellulose II nanocrystals were prepared by two different methods: (1) sulfuric acid hydrolysis of cellulose previously mercerized with 18.5 wt% NaOH (CNC-II), (2) mercerization of CNC-I with 18.5 wt% NaOH (MCNC-II). Cellulose III nanocrystals were prepared by ethylenediamine treatment of CNC-I (ECNC-III). The polymorphic changes of CNCs, and their properties including morphology, crystallinity, thermal stability, and re-dispersion ability were systematically investigated. The results showed that the other properties of CNC-II and MCNC-II were quite different from each other except for the morphology. The morphology of polymorphic transformed CNCs were strongly relate to the fashion of cellulose chains arrangement. Both CNC-II and MCNC-II exhibited a rod-like shape with short lengths, whereas the ECNC-III showed relatively long length, like CNC-I.