Effective viscosity of a concentrated suspension of uncharged spherical soft particles.
Effective viscosity of a concentrated suspension of uncharged spherical soft particles.
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不带电球形软颗粒的浓缩悬浮液的有效粘度。
DOI：
10.1021/la904121p
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
H. Ohshima
中科院分区：
文献类型：
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作者：
H. Ohshima
我们提出了一个理论的有效粘度eta(s)的不带电的聚合物包覆球形颗粒的浓缩悬浮液，称为不带电的球形软颗粒，粘度eta的液体的基础上的细胞模型。这些粒子由半径为a的不带电粒子核心组成，上面覆盖着厚度为d的不带电聚合物层（因此，聚合物包覆的粒子具有内半径a和外半径b = a + d）。我们假设聚合物段作为阻力中心，对在聚合物层中流动的液体施加摩擦力——gamma u，其中u是液体速度，gamma是摩擦系数。我们推导了悬浮液的有效粘度eta(s)的解析表达式，它取决于半径a和b，球体的体积分数phi和参数lambda = (gamma/eta)（1/2）。得到的eta(s)表达式显示出正确的极限行为。也就是说，当φ -> 0时，得到的eta(s)的表达式变成了不带电软球的稀悬液的表达式（Ohshima, Langmuir 2008,24, 6453）。当-> 0时，得到的黏度表达式变为不带电的多孔球体(Ohshima, Colloids Surf。Physicochem。Eng。《星象》2009,347,33)。在a—> 0和phi—> 0的进一步极限下，得到的黏度表达式成为Natraj和Chen （J.胶体界面科学，2002,251,200）对不带电多孔球体的稀悬浮的黏度表达式。当λ ->无穷大或a -> b时，得到的黏度表达式趋向于Simha的结果(J. appll。对于半径为b的不带电刚性球的集中悬浮，而当λ -> 0时，它变成了半径为a的不带电刚性球的集中悬浮。
We present a theory of the effective viscosity eta(s) of a concentrated suspension of uncharged polymer-coated spherical particles, which are termed uncharged spherical soft particles, in a liquid of viscosity eta on the basis of a cell model. These particles consist of the uncharged particle core of radius a covered with an uncharged polymer layer of thickness d (a polymer-coated particle thus has an inner radius a and an outer radius b = a + d). We assume that polymer segments are regarded as resistance centers, exerting frictional forces--gamma u on the liquid flowing in the polymer layer, where u is the liquid velocity and gamma is the frictional coefficient. We derive an analytic expression for the effective viscosity eta(s) of the suspension, which depends on the radii a and b, and volume fraction phi of the spheres and a parameter lambda = (gamma/eta)(1/2). The obtained expression for eta(s) exhibits the correct limiting behaviors. That is, as phi --> 0, the obtained expression for eta(s) becomes that for a dilute suspension of uncharged soft spheres (Ohshima, Langmuir 2008, 24, 6453). As a --> 0, the obtained viscosity expression becomes that for the case of a concentrated suspension of uncharged porous spheres (Ohshima, Colloids Surf. A: Physicochem. Eng. Aspects 2009, 347, 33). In the further limit of a --> 0 and phi --> 0, the obtained viscosity expression becomes the viscosity expression derived for the case of a dilute suspension of uncharged porous spheres by Natraj and Chen (J. Colloid Interface Sci. 2002, 251, 200). As lambda --> infinity or a --> b, the obtained viscosity expression tends to Simha's result (J. Appl. Phys. 1952, 23, 1020) for a concentrated suspension of uncharged rigid spheres of radius b, while as lambda --> 0, it becomes that for uncharged rigid spheres of radius a.