Electrorheological behavior of whisker suspensions under oscillatory shear
Electrorheological behavior of whisker suspensions under oscillatory shear
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DOI：
10.1016/j.colsurfa.2006.11.050
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发表时间：
2007-05
期刊：
影响因子：
--
通讯作者：
Kazutoshi Tsuda;Yasuto Takeda;H. Ogura;Y. Otsubo
中科院分区：
文献类型：
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作者：
Kazutoshi Tsuda;Yasuto Takeda;H. Ogura;Y. Otsubo
在外加电场作用下，测量了球形和晶须颗粒悬浮液在振荡剪切下的流变性。由于悬浮液由粘性流体转变为具有高屈服应力的塑性体，在电场作用下，其复剪切模显著增大。当应力幅值超过屈服应力时，由于结构破裂，复剪切模急剧减小。然而，在应力幅值超过静态带电屈服值的条件下，振荡剪切带电的晶须悬浮液的复剪切模有较大幅度的提高。屈服应力的发展归因于平行于场矢方向的粒子链结构。在实际的电流变悬浮液中，决定屈服应力的最重要的因素是由多个链聚集而成的柱结构。微观观察表明，外部振荡运动使聚集区的颗粒浓度增加。振荡剪切作用下晶须悬浮液电流变性能的提高可以用振荡剪切引起的柱体增厚来解释。
The rheological properties of suspensions of sphere and whisker particles were measured under oscillatory shear on the application of electric fields. Because the suspensions are converted from viscous fluids to plastic bodies with high yield stresses, the complex shear modulus is markedly increased in electric fields. When the stress amplitude is increased beyond the yield stress, the complex shear modulus shows a drastic reduction due to the structural rupture. However, the complex shear modulus of whisker suspensions electrified during oscillatory shear is increased to a great extent, under the conditions where the stress amplitude exceeds the yield value attained by electrification in a quiescent state. The development of yield stress is attributed to the chain structures of particles in direction parallel to the field vector. In actual ER suspensions, the most important factor determining the yield stress is the column structure consisting of aggregations of many chains. The microscopic observation indicates that the particle concentration in aggregated region is increased by external oscillatory motion. The enhancement of ER performance for whisker suspensions electrified under oscillatory shear can be explained by the column thickening induced by oscillatory shear.