Effects of Shear on the Smectic A Phase of Thermotropic Liquid Crystals
Effects of Shear on the Smectic A Phase of Thermotropic Liquid Crystals
复制标题
剪切对热致液晶近晶A相的影响
DOI：
10.1051/jp2:1995130
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
D. Roux
中科院分区：
文献类型：
--
作者：
P. Panizza;P. Archambault;D. Roux
研究了热致液晶 4-氰基-4'-辛基联苯 (BCB) 近晶 A 相的流变行为。进行剪切流下的 X 射线散射研究以探测结构的变化我们发现，在一定的温度范围内，存在两种片层取向状态。这两种取向稳态由一阶动态转变分开，该一阶动态转变在与近晶/向列转变不同的Tc1a温度下变得连续。在低剪切速率下，近晶 A 相是非牛顿相：其粘度 ~ 随 (Tc T)~/~ i~~/~ 变化（其中 ~ 是剪切速率，T 是温度）。在这种情况下，系统的结构与沿流动方向定向的多层圆柱体相容。在高剪切速率下，系统变成牛顿式，然后其各层
The rheological behaviour of the smectic A phase of the thermotropic liquid crystal 4-cyano-4'-octylbiphenyl (BCB) is examined. X-ray scattering studies under shear flow were performed to probe changes of structures We found that in a certain range of temperatures two states of orientation of lamellae exist. These two steady states of orientation are separated by a first order dynamic transition that becomes continuous at Tc la temperature different from that of the smectic/nematic transition). At low shear rates, the smectic A phase is non-Newtonian: its viscosity ~ varies as (Tc T)~/~ i~~/~ (where ~ is the shear rate and T the temperature). In this regime, the structure of the system is compatible with multilamellar cylinders oriented along the flow direction At high shear rates, the system becomes Newtonian, its layers are then