羟乙基纤维素溶液的触变性与反触变性

Thixotropy and Anti-thixotropy of Hydroxyethyl Cellulose Aqueous Solutions

对于高分子流体流动特性的研究不仅能够判断该流体的应用价值,而且还可以用于分析流体内部的结构特点和结构演变过程,建立流体的结构与性能关系。以羟乙基纤维素(HEC)为研究对象,研究了HEC在水-乙醇和水-乙二醇溶液体系中的流动性质。结果表明,HEC/水-乙醇溶液会发生从触变性到反触变性的转变,溶液稳态黏度随着乙醇体积分数的增加先升后降;HEC/水-乙二醇溶液的流动特性更加复杂,虽然也会发生从触变性到反触变性的转变,但是,相对低浓度的HEC溶液的稳态黏度随乙二醇体积分数的增加线性增长,而相对高浓度的HEC溶液的稳态黏度却在乙二醇体积分数为15%和40%处出现两个极大值。结果表明:在体系中引入乙醇和乙二醇后,由于非溶剂效应以及两种醇分子与HEC分子间的氢键作用,使得HEC在溶液中产生了不同的聚集状态,该聚集状态在持续剪切的作用下又不断发生改变,从而影响了溶液的流动性质。

Study on the flowing property of polymer fluids is not only suitable in evaluating their application, but also valuable in exploring the texture of the flowing system and its evolution, that is, the relationship between the structure and the properties of the fluids. The hydroxyethyl cellulose （HEC） was chosen as the model compound. The flowing property of the HE（; in different aqueous solutions was studied. The results showed that there was similar transition from thixotropy to anti-thixotropy for both HEC/water-ethanot solutions and HEC/water-glycol solutions. There was only one maximum value of equilibrium viscosity for the HEC/water-ethanol solutions in lower concentra- tion or higher concentration. It increased first, but decreased later with the increasing of volume fraction of the etha- nol. However, the flowing property of the HEC/water-glycol solutions showed to be more complex. There was no maximum value of equilibrium viscosity for the HEC/water-glycol solutions of lower concentration （0. lwt~./00）. It in- creased linearly with the increasing of volume fraction of the glycol; whereas, there were two maximum value corre- sponding to glycol volume fraction of 15% and 40~//oo for the HEC/water-glycol solutions of higher HEC concentration （1.0wt~）. It was speculated that there were different aggregation states of HEC in water-ethanol or in water-glycol solutions, which were resulted from the non-solvent effect and the different interactions between the ethanol/glycol with the HEC molecules. The aggregations of HEC molecules in solutions experienced destruction and recombination under the constant shearing, which lead to the violent variation of the flowing properties.