球形膠體粒子於卡羅流體中對平板之電泳行為

Electrophoretic Behavior of a Spherical Colloidal Particle to a Plane in Carreau Fluid

陳其田(Chi-Tien Chen)

指導教授 ： 李克強

國立臺灣大學/工學院/化學工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.00266

摘要

本研究中主要探討一帶電球形膠體粒子於高分子流體中相對於平板之電泳行為。吾人以卡羅流體模型描述高分子流體行為，此模型特別適合描述具有剪力稀薄現象的流體。在低表面電位及弱外加電場的假設下，將方程式線性化，並利用假性光譜法求解聯立之電場、離子濃度場以及流場方程組。
吾人發現不少與傳統膠體粒子於牛頓流體中不同的行為。當卡羅流體參數 (冪次常數)愈小或 (鬆弛時間常數)愈大時，代表此流體行為愈偏離牛頓流體，亦即剪力稀薄效應愈明顯，則膠體粒子的電泳速度會愈快。當膠體粒子愈接近平板時，由於邊界效應的影響，剪力稀薄的效應會愈明顯，粒子之電泳速度相較於在牛頓流體中會愈快。

關鍵字

邊界效應 ； 電雙層 ； 電泳速度 ； 卡羅流體 ； 剪力稀薄

並列摘要

In this study, we investigated the electrophoretic behavior of a charged spherical colloidal particle in polymeric fluid with the presence of a planar surface. We adopted Carreau model to describe the polymeric fluid, which is widely used on describing polymeric fluid with shear-thinning nature. The corresponding electrokinetic equations are further linearized based on the assumptions of low zeta potential and weak applied field, and solved simultaneously by pseudo-spectral method.
We found several interesting phenomena which can not be observed in typical Newtonian cases. For instance, under lower (the power law exponent) or higher (the relaxation time constant), the higher the mobility. This is because the fluid property deviates from Newtonian, the shear thinning nature is more obvious. On the other hand, the closer the planar surface to the colloidal is, the mobility will become higher than that in the case of Newtonian fluid. This is because the shear-thinning effect is enhanced by the presence of the boundary.

並列關鍵字

double layer ； boundary effect ； shear thinning ； Carreau fluid ； electrophoretic mobility

參考文獻

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