Effect of magnetic field on discotic nematic liquid crystalline polymers under simple shear flow
Effect of magnetic field on discotic nematic liquid crystalline polymers under simple shear flow
复制标题
简单剪切流下磁场对盘状向列液晶聚合物的影响
DOI：
10.1002/app.38268
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发表时间：
2013
影响因子：
3
通讯作者：
Xuan
中科院分区：
文献类型：
--
作者：
S. Fu;JingBAI;Xuan
利用扩展的Doi理论分析了磁场对盘状向列液晶聚合物（LCP）的影响，其中分子形状参数（β）定义为-1.0。无需任何闭包近似即可求解盘状向列型 LCP 分子概率函数的演化方程。流动方向模式之间的转变，例如类似于棒状 LCP 定义的翻滚、摇摆和排列，受到磁场的强烈影响。在磁场下观察到的棒状 LCP 的新排列流动取向模式也可以在较低剪切速率区域进行研究。另一方面，还研究了平行于 x 轴和 y 轴的磁场对时间平均第一和第二法向应力差 ( , ) 的影响。可以看出， 、 的符号变化的剪切速率区域与棒状LCP 得出的结论完全相反。此外，由于新的对准流动方向模式，在较低剪切速率范围内，绝对值随着磁场强度的增加而增加。最后，还讨论了流动相图与 β 的关系。 © 2012 Wiley periodicals, Inc. J. Appl。聚合物。科学，2013
The effect of magnetic field on the discotic nematic liquid crystalline polymers (LCPs) is analyzed with the extended Doi theory, in which the molecular shape parameter (β) is defined at −1.0. The evolution equation for the probability function of the discotic nematic LCP molecules is solved without any closure approximations. The transition among flow-orientation modes, such as tumbling, wagging, and aligning defined similar to the rodlike LCPs, is strongly affected by the magnetic fields. The new aligning flow-orientation mode observed for the rodlike LCPs under magnetic fields also can be investigated in the lower shear rate region. On the other hand, the effect of magnetic fields parallel to the x- and y-axis on the time-averaged first and second normal stress differences ( , ) are also studied. It can be seen that the shear rate regions of the sign changes of , are completely contrary to those conclusions achieved for the rodlike LCPs. In addition, the absolute values of increase with the magnetic field strength in the lower shear rate range owing to the new aligning flow-orientation mode. Finally, the flow-phase diagram versus β is also discussed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013