中文摘要：

利用布朗动力学模拟和基于管子模型的GLaMM理论计算,探讨了缠结高分子流体在近平衡态和快速启动形变下的流变行为.结果表明,在线性区,除了一些较小的偏离外（例如,在Rouse松弛时间尺度上,GLaMM理论计算的应力松弛快于其实验测量值）,GLaMM理论与实验基本吻合.然而,在快速启动形变下,即使把时间尺度换为τd,理论与模拟仍有显著差异,这些结果完全证实了我们先前作出的被拉伸的缠结网络抑制解缠结发生、应力过冲的分子机理是被拉伸的高分子链发生回缩等重要结论.此外,模拟还发现应力过冲点所对应的应变值随剪切速率的增加而增加,这一结果与现有的大量实验结果吻合,但是与管子模型的期望完全不符.这些发现质疑了管子模型分子链在光滑无势垒管道中自由收缩的分子图像.

英文摘要：

Using Brownian dynamics simulation and calculations of the most sophisticated version of the tube model,the GLaMM model,we explore the near equilibrium and fast startup shear rheological behavior of entangled polymer fluids. In the nearly linear flow regime a detailed comparison between the rheometric measurements and GLaMM theoretical calculations is performed. The overall agreement is found to be satisfactory but several minor disagreements,e. g.,the measurements and calculations reveal totally different stress relaxation dynamics on the time scale in units of t / τR. However,during startup shear,an explicit comparison between the simulation and the theoretical description from the GLaMM theory shows irreconcilable differences on the time scale in units of t / τd,which confirms our previous results,but the difference can disappear in the nearly linear flow regime. In addition,the results of our simulations about the relationship between the strain γmaxat the overshoot point and WiRor t / τRare also compared and found to behave in a very similar manner with several literature data sets but disagree with those predicted by the GLaMM theory. These findings call into question the barrier-free chain retraction mechanism as envisioned in the tube model.