School of Engineering, Zhejiang A&F University, Hangzhou 311300, China.
College of Chemistry and Molecular Science, Wuhan University, Wuhan 430072, China.
Molecules. 2021 May 27;26(11):3201. doi: 10.3390/molecules26113201.
Water-soluble cellulose ethers are widely used as stabilizers, thickeners, and viscosity modifiers in many industries. Understanding rheological behavior of the polymers is of great significance to the effective control of their applications. In this work, a series of cyanoethylcellulose (CEC) samples with different molecular weights were prepared with cellulose and acrylonitrile in NaOH/urea aqueous solution under the homogeneous reaction. The rheological properties of water-soluble CECs as a function of concentration and molecular weight were investigated using shear viscosity and dynamic rheological measurements. Viscoelastic behaviors have been successfully described by the Carreau model, the Ostwald-de-Waele equation, and the Cox-Merz rule. The entanglement concentrations were determined to be 0.6, 0.85, and 1.5 wt% for CEC-11, CEC-7, and CEC-3, respectively. All of the solutions exhibited viscous behavior rather than a clear sol-gel transition in all tested concentrations. The heterogeneous nature of CEC in an aqueous solution was determined from the Cox-Merz rule due to the coexistence of single chain complexes and aggregates. In addition, the CEC aqueous solutions showed good thermal and time stability, and the transition with temperature was reversible.
水溶性纤维素醚作为稳定剂、增稠剂和粘度调节剂，在许多行业中得到广泛应用。了解聚合物的流变行为对于有效控制其应用具有重要意义。在这项工作中，在 NaOH/尿素水溶液中，通过均相反应将纤维素和丙烯腈制备了一系列具有不同分子量的氰乙基纤维素（CEC）样品。使用剪切粘度和动态流变学测量研究了水溶性 CEC 作为浓度和分子量函数的流变性质。粘弹性行为成功地用 Carreau 模型、Ostwald-de-Waele 方程和 Cox-Merz 规则进行了描述。CEC-11、CEC-7 和 CEC-3 的缠结浓度分别确定为 0.6、0.85 和 1.5wt%。在所有测试浓度下，所有溶液均表现出粘性行为，而不是明显的溶胶-凝胶转变。由于单链复合物和聚集体的共存，从 Cox-Merz 规则确定了 CEC 在水溶液中的非均相性质。此外，CEC 水溶液具有良好的热稳定性和时间稳定性，且温度转变是可逆的。
