刚性聚合物稀溶液流变性质的计算 Ⅱ.非定常流动

本文继续前一篇文章讨论描述刚性聚合物稀溶液流变性质的多棒刚杆分子模型,计算了应力发展的非定常剪切流动,结果表明,η~+将有所希望的“过冲”现象,且在无因次时间常数τ≥5后,流变性质达到定常均匀剪切流的结果,同时亦可方便地导得多球刚杆分子模型和无水学相互作用的刚性哑铃模型的结果。这些结果表明,此模型是较为完善的描述刚性聚合物稀溶液的分子模型。本文还对W_e≤0.7的情况作了深入的分析,比较了各阶近似解的计算结果。表明在W_e≤0.7时,用二阶近似解可代替高阶近似解计算,不会造成很大的误差,但可大大缩短计算时间。

RHEOLOGY OF DILUTE SOLUTIONS OF RIGID RODLIKE MACROMOLECULAR

In this paper, we continue to discuss the theological properties of suspension of multi-rod rod model in unsteady flow and calculate the material functions after inception of steady shear. The results revealed that the curves of material functions monotonically approached their steady-state values when the Weissenberg number was relatively small, and the expected overshoot of the curves of material functions would appear when we was large enough, and that the transent phenomena of matreial functions almost totally disappeared after τ= t/λN(1)≥5. The results of multi-bead and rigid dumbbell models without the hydrodynamic interaction can be derived from this model with ease. All above mentioned indicate that the model is most sophisticated one of describing the dilute solutions of rigid rodlike polymer. In the paper, we made a detailed analysis for the case of W6=0.7 and a comparison between approimate solutions of various orders. When We < 0.7, we can adopt the second order approximate solution instead of the high order numerical solution to minimize the calculation and without the risk of producing a untolerable error.