Rheological behavior of dilute solutions of a side-chain liquid-crystalline polysiloxane in 4,4′-n-octylcyanobiphenyl
Rheologica Acta(2000)
摘要
The electrorheological (ER) behavior and stress transient response of dilute solutions of a side-chain liquid-crystalline polysiloxane (LCP) in 4,4′-n-octylcyanobiphenyl (8CB) is studied. In the flow-tumbling regime of 8CB, i.e. from T = 34–38 °C, the stress transients of both 8CB and LCP/8CB solutions show oscillatory responses, but with shorter oscillation periodicities for the solution. In the flow-aligning regime of 8CB, i.e. at 39 and 40 °C, a transformation to flow-tumbling is observed in the stress transients of the LCP/8CB solution. In both cases, analysis of the transient responses indicates that the change in Leslie viscosity coefficients on dissolving the LCP are δα 2 < 0 and δα 3 > 0. The amplitude of the ER response, defined as the viscosity difference between the on and off states, Δη = η on − η off , is only weakly affected by the dissolution of LCP. These rheological results can be interpreted consistently using a modified version of a hydrodynamic theory by Brochard, provided an additional dissipation mechanism is included, which derives from the presence of an elastic torque between director rotation and LCP orientation.
更多查看译文
关键词
Key words Electrorheology,Liquid crystal,Polymer solutions
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要