College of Material Science and Engineering, Tianjin Polytechnic University, Tianjin 300387, PR China.
Carbohydr Polym. 2014 Jan;99:132-9. doi: 10.1016/j.carbpol.2013.08.025. Epub 2013 Aug 23.
The rheological properties of α-cellulose 1-allyl-3-methylimidazolium formate solutions were investigated using shear viscosity and dynamic rheological measurements in a large range of concentrations (0.1-10 wt%) at 25 °C. In steady shear measurement, the overlap concentration (c*) and the entanglement concentration (c(e)) were determined to be 0.5 and 2.0 wt% respectively, and the exponents of the specific viscosity (η(sp)) versus the concentration (c) were determined as 1.0, 2.0 and 4.7 for dilute, semidilute unentangled and entangled regimes respectively, which were in accordance with the scaling prediction for neutral polymer in θ solvent. The slopes of the relaxation time (τ) against the concentration for semidilute unentangled and entangled regimes were observed as 1.0 and 2.5 respectively. In dilute and semidilute unentangled regimes, failure of the Cox-Merz rule with steady shear viscosity larger than complex viscosity was observed; while the deviation from the Cox-Merz rule disappeared in semidilute entangled regime.
采用剪切黏度和动态流变学测量方法，在 25°C 下研究了α-纤维素 1-烯丙基-3-甲基咪唑甲酸酯在很宽浓度范围内（0.1-10wt%）的流变性。在稳态剪切测量中，分别确定了重叠浓度（c*）和缠结浓度（c(e)）为 0.5 和 2.0wt%，比浓黏度（η(sp)）与浓度（c）的指数分别为 1.0、2.0 和 4.7，适用于θ溶剂中中性聚合物的标度预测。观察到半稀无缠结和缠结区的弛豫时间（τ）对浓度的斜率分别为 1.0 和 2.5。在稀溶液和半稀无缠结区，观察到稳态剪切黏度大于复黏度时，Cox-Merz 规则失效；而在半稀缠结区，Cox-Merz 规则的偏差消失。
