期刊
CARBOHYDRATE POLYMERS
卷 229, 期 -, 页码 -出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.carbpol.2019.115539
关键词
Cellulose nanocrystal; Sulfuric acid hydrolysis; Cellulose supramolecular structure; X-ray diffraction; Yield
资金
- Guangzhou Science and Technology Bureau [201904010308]
- Guangdong Government Science and Technology [2017B020238003, 2014B050505019]
Cellulose nanocrystals with cellulose I and II allomorphs (CNC-I and CNC-II) were prepared from eucalyptus cellulose I substrate by controlling the sulfuric acid hydrolysis conditions, including acid concentration (56- 64 wt%), reaction temperature (45 or 60 degrees C) and time (10-120 min). The crystalline structures were verified by XRD and C-13-NMR. CNC-II only appeared at very restricted reaction conditions. The rapid cellulose supramolecular structure transition under sulfuric acid concentration of around 60 wt% resulted in an abrupt change in CNC yield. A maximal CNC yield of 66.7% was obtained at acid concentration of 58 wt% and reaction temperature of 60 degrees C. CNC-I exhibited spindle-shape, while CNC-II showed a twisted strip structure. The state of order in cellulose during the acid hydrolysis process has been studied using a coagulation method. A tentative model of CNC-I and CNC-II formation was then proposed. This work provided significant knowledge for the production of CNCs with high yield and controllable allomorph.
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