Influence of Water on the Structure and Dielectric Properties of the Microcrystalline and Nano-Cellulose.
Influence of Water on the Structure and Dielectric Properties of the Microcrystalline and Nano-Cellulose.
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DOI：
10.1186/s11671-017-2231-5
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发表时间：
2017-12
影响因子：
--
通讯作者：
Tkachov SY
中科院分区：
文献类型：
--
作者：
Kovalov KM;Alekseev OM;Lazarenko MM;Zabashta YF;Grabovskii YE;Tkachov SY
利用X射线、热重和介电谱研究了不同状态的水对微晶纤维素结构和介电性能的影响。对不同含水量的微晶纤维素(MCC)的研究表明，水分子位于MCC的大孔和多分子水合层中。结果表明，随着水合壳中水浓度的增加，微晶表面的纤维素分子发生重组，其结果是，它们的横向尺寸和结晶度增加。结果表明，在水的浓缩过程中，超过13%的微晶连续水合壳出现。研究了频率为 f = 5、10、20 和 50 kHz 时，温度范围 [−180 ÷ 120] °C 下复介电常数实部和虚部的温度依赖性。观察到低温弛豫过程和高温转变。与纤维素构象分子表面羟甲基从tg向tt转变有关的低温弛豫过程随着微晶纤维素中水浓度的增加而向低温转移。
Influence of water in the different states on a structure and dielectric properties of microcrystalline cellulose were studied by of X-ray, thermogravimetry, and dielectric spectroscopy. At research of microcrystalline cellulose (MCC) with different content of water, it is shown that the molecules of water are located in the macropores of MCC and in multimolecular hydrated layers. It is shown that at the increase of concentration of water in a hydrated shell, the reorganization of molecules of cellulose in the surface of crystallites takes place, and as a result, their transversal size and crystallinity increase. It is shown that during the concentration of water, more than 13% in a continuous hydrated shell of crystallites appears. Temperature dependences of actual and imaginary parts of complex dielectric permittivity were studied in the interval of temperatures [−180 ÷ 120] °C on frequencies of f = 5, 10, 20, and 50 kHz. A low-temperature relaxation process and high-temperature transition were observed. Low-temperature relaxation process which is related to transition of surface methylol groups of molecules of cellulose conformation from tg to tt is shifted toward low temperatures at the increase of concentration of water in microcrystalline cellulose.
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影响因子：
3.3
作者：
Le Bras, David;Stromme, Maria;Mihranyan, Albert
通讯作者：
Mihranyan, Albert
影响因子：
9.5
作者：
Safari, Salman;van de Ven, Theo G. M.
通讯作者：
van de Ven, Theo G. M.
影响因子：
3.3
作者：
Samir, MASA;Alloin, F;Dufresne, A
通讯作者：
Dufresne, A
影响因子：
4.6
作者：
Gelin, Kristina;Bodin, Aase;Stromme, Maria
通讯作者：
Stromme, Maria
影响因子：
5.8
作者：
Mihranyan, A;Llagostera, AP;Ek, R
通讯作者：
Ek, R