剪切扰动对液晶聚合物流变行为影响的数值模拟

摘要

The complex rheological behavior of liquid crystalline polymers solutions in the shear flow with perturbations is investigated using the finite volume method. The perturbations of simple shear can be considered as one arising from the addition of a slight extensional component to the velocity gradient. Firstly, the case in the simple shear flow is focused upon, i.e. , the perturbation equal to zero,and some classical solutions can be obtained for various parameter values. This is the preparation for the discussion of perturbation cases, and to check the validity of numerical method. Then, the effect of slight perturbations on the transition to the flow type of liquid-crystalline polymers (LCPs) is explored in detail. Results indicate that the mechanism of transformation is different for low and high shear rates. Finally, rheological predictions and some micro properties of orientation are also obtained from the perturbation system, and the results show that the effect of perturbations in flow type can also significantly change the related material functions.%采用有限体积数值方法模拟了剪切扰动条件下液晶聚合物的复杂流变性特性.其中剪切扰动系统通过给速度梯度施加一项额外小量而实现.首先,考虑了扰动为零的简单剪切流情形,分别得到了各种典型的分子运动状态,不但为剪切扰动的定性分析作了准备,而且也验证了数值算法的有效性.然后,重点研究了剪切扰动对分子运动行为转变的影响,数值结果表明流场中微小的剪切扰动在低剪切率和高剪切率下对分子演化状态的转变机理并不相同.此外,进一步预测了液晶聚合物流变行为及微观特性的变化,结果发现流场的扰动作用也会显著地改变其相应的物性函数.