Mines ParisTech, Centre de Mise en Forme des Matèriaux-CEMEF, UMR CNRS/Ecole des Mines de Paris 7635, BP 207, 06904 Sophia-Antipolis, France.
J Phys Chem B. 2010 Jun 3;114(21):7222-8. doi: 10.1021/jp1024203.
The viscosities of microcrystalline cellulose dissolved in 1-ethyl-3-methylimidazolium acetate (EMIMAc) and in 1-butyl-3-methylimidazolium chloride (BMIMCl) were studied in detail as a function of polymer concentration and temperature. The goal was to compare the flow of solutions, macromolecule hydrodynamic properties in each solvent, and the activation energies of viscous flow. Intrinsic viscosities were determined using the truncated form of the general Huggins equation. In both solvents cellulose intrinsic viscosity decreases with increasing temperature, indicating the decrease of solvent thermodynamic quality. The activation energies for both types of cellulose solutions were calculated. For cellulose-EMIMAc the Arrhenius plot showed a concave shape, and thus the Vogel-Tamman-Fulcher (VTF) approach was used. We suggest an improved method of data analysis for the determination of VTF constants and demonstrate that cellulose-EMIMAc solution viscosity obeys VTF formalism. Once the dependences of Arrhenius activation energy and VTF pseudo-activation energy were obtained for the whole range of concentrations studied, they were all shown to be described by a simple power-law function of polymer concentration.
详细研究了微晶纤维素在 1-乙基-3-甲基咪唑醋酸盐（EMIMAc）和 1-丁基-3-甲基咪唑盐酸盐（BMIMCl）中的溶解粘度作为聚合物浓度和温度的函数。目的是比较溶液的流动、每种溶剂中大分子流体动力学性质和粘流的活化能。使用广义 Huggins 方程的截断形式确定特性粘度。在两种溶剂中，纤维素的特性粘度随温度升高而降低，表明溶剂热力学质量下降。计算了两种类型纤维素溶液的活化能。对于纤维素-EMIMAc，Arrhenius 图呈凹形，因此采用 Vogel-Tamman-Fulcher（VTF）方法。我们提出了一种改进的数据分析方法，用于确定 VTF 常数，并证明纤维素-EMIMAc 溶液粘度符合 VTF 形式。一旦获得了研究浓度范围内的 Arrhenius 活化能和 VTF 拟活化能的依赖性，它们都可以用聚合物浓度的简单幂律函数来描述。
