Knoben W, Besseling N A M, Cohen Stuart M A
Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands.
J Chem Phys. 2007 Jan 14;126(2):024907. doi: 10.1063/1.2409296.
The rheology of a reversible supramolecular polymer is studied by comparing the effects of an increase in temperature and the addition of chain stoppers. The dependence of the zero-shear viscosity and the terminal relaxation time on temperature is exponential, and the activation energy for viscous flow can be calculated. Above a critical stopper fraction, power laws describe the stopper dependence of the viscosity and relaxation time. A simple model for the effect of the addition of chain stoppers on the average degree of polymerization adequately describes the results. A comparison of flow curves at several temperatures and stopper fractions reveals considerable differences between solutions with the same zero-shear viscosity. These are mainly associated with differences in the terminal relaxation time. A mechanism of shear-induced alignment and subsequent elongation of chains is proposed, with which the experimental results are consistent.
通过比较温度升高和添加链终止剂的影响，研究了一种可逆超分子聚合物的流变学。零剪切粘度和末端松弛时间对温度的依赖性呈指数关系，并且可以计算粘性流动的活化能。在临界终止剂分数以上，幂律描述了粘度和松弛时间对终止剂的依赖性。一个关于添加链终止剂对平均聚合度影响的简单模型充分描述了结果。对几个温度和终止剂分数下的流动曲线进行比较，发现在相同零剪切粘度的溶液之间存在相当大的差异。这些差异主要与末端松弛时间的差异有关。提出了一种剪切诱导链排列和随后链伸长的机制，实验结果与之相符。
