论文标题
稀聚合物溶液的粘性函数和类动光特性：Fene-Fene-fraenkel哑铃与棒状模型的比较
Viscometric Functions and Rheo-optical Properties of Dilute Polymer Solutions: Comparison of FENE-Fraenkel Dumbbells with Rodlike Models
论文作者
论文摘要
传统上，在轮廓长度（或更大）上持久长度的刚性大分子或聚合物链被建模为杆或非常僵硬的弹簧。 Fene-Fene-spring哑铃，对于具有可调的谐波刚度的非零天然长度，它是有限的，它是一种这样的模型，以前已证明在没有流体动力相互作用的情况下可以再现珠rod行为。 Fene-fraenkel Spring的力量定律减少了Hookean或Fene Spring Force Law，以适当选择的弹簧参数值。因此，可以通过适当地改变参数来探索珠子弹簧和珠rod行为的限制之间的跨界区域。在这项研究中，使用半平均预测型布朗动力学算法，当精心选择弹簧刚度，可扩展性和仿真时间段时，表现出Fene-Fene-fraenkel Spring可模仿具有流体动力相互作用的杆。通过放松弹簧刚度和可扩展性，Fene-fraenkel Spring还可以再现类似弹簧的行为，例如跨界频率从$ -1/3 $到$ -2/3 $ -2/3 $ -2/3 $ power-Laws以剪切速度的粘度缩放，以及从正极速率变为正面的第二个正常应力差。此外，与高宽高比的粘度和线性二色性的实验数据进行了比较，刚性大分子表明，与棒状模型相比，Fene-Fene-Fraenkel Spring的可扩展性和刚度可在建模不足道的不足道分子时相等或提高精度。
Rigid macromolecules or polymer chains with persistence length on the order of the contour length (or greater) have traditionally been modelled as rods or very stiff springs. The FENE-Fraenkel-spring dumbbell, which is finitely extensible about a non-zero natural length with tunable harmonic stiffness, is one such model which has previously been shown to reproduce bead-rod behaviour in the absence of hydrodynamic interactions. The force law for the FENE-Fraenkel spring reduces to the Hookean or FENE spring force law for appropriately chosen values of the spring parameters. It is consequently possible to explore the crossover region between the limits of bead-spring and bead-rod behaviour by varying the parameters suitably. In this study, using a semi-implicit predictor-corrector Brownian dynamics algorithm, the FENE-Fraenkel spring is shown to imitate a rod with hydrodynamic interactions when spring stiffness, extensibility and simulation timestep are chosen carefully. By relaxing the spring stiffness and extensibility, the FENE-Fraenkel spring can also reproduce spring-like behaviour, such as a crossover from $-1/3$ to $-2/3$ power-law scaling in the viscosity with shear rate, and a change from positive to negative second normal stress difference. Furthermore, comparisons with experimental data on the viscosity and linear dichroism of high aspect ratio, rigid macromolecules shows that the extensibility and stiffness of the FENE-Fraenkel spring allows for equal or improved accuracy in modelling inflexible molecules compared to rodlike models.
