A comparative study on the preparation and characterization of cellulose nanocrystals with various polymorphs
A comparative study on the preparation and characterization of cellulose nanocrystals with various polymorphs
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DOI：
10.1016/j.carbpol.2018.04.039
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发表时间：
2018-09-01
影响因子：
11.2
通讯作者：
Li, Jun
中科院分区：
文献类型：
--
作者：
Gong, Jie;Mo, Lihuan;Li, Jun
纤维素纳米晶的多晶型变化与其性质和应用密切相关。在这项研究中，具有不同的多晶型的CNCs的生产通过一个简单的多晶型转化处理。通过典型的硫酸水解（CNC-I）制备纤维素I纳米晶体。通过两种不同的方法制备纤维素II纳米晶体：（1）预先用18.5wt%NaOH丝光的纤维素的硫酸水解（CNC-II），（2）用18.5wt%NaOH丝光的CNC-I（MCC-II）。通过乙二胺处理CNC-I（ECNC-III）制备纤维素III纳米晶。系统地研究了纳米碳的晶型变化及其形态、结晶度、热稳定性和再分散能力等性能。结果表明，CNC-II和MCC-II除了形貌不同外，其他性能都有很大差异。多晶型转化CNCs的形态与纤维素链的排列方式密切相关。CNC-II和MCC-II都表现出短长度的棒状形状，而ECNC-III表现出相对较长的长度，如CNC-I。
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.