Osmotic pressure and viscoelastic shear moduli of concentrated emulsions
Osmotic pressure and viscoelastic shear moduli of concentrated emulsions
复制标题
DOI：
10.1103/physreve.56.3150
复制
发表时间：
1997-09-01
影响因子：
2.4
通讯作者：
Weitz, DA
中科院分区：
文献类型：
--
作者：
Mason, TG;Lacasse, MD;Weitz, DA
我们对通过渗透压 Pi 浓缩的单分散乳液的复数剪切模量 G*(omega,phi) 的频率 omega 依赖性和体积分数 phi 依赖性进行了实验研究。在给定 phi 下，弹性储能模量 G'(omega)=Re[G*(omega)] 表现出低频平台 G'(p)，支配着表现出最小值的耗散损耗模量 G''(omega)=Im[G*(omega)]。在临界堆积分数 phi(c) 之上，我们发现 Pi(phi) 和 G'(p)(phi) 均呈拟线性增加，缩放比例为 (phi-phi(c))(mu)，其中 phi(c) 近似于 phi(c)(rcp)（球体随机密堆积的体积分数），mu 是接近于 1 的指数。为了解释这一结果，我们基于压缩液滴获得的结果，开发了一个无序液滴模型，该模型通过有效的排斥非谐势相互作用。基于该模型的模拟计算出静态剪切模量 G 和渗透压 Pi，它们与 G'(p) 和 Pi 的实验值非常吻合。
We present an experimental study of the frequency omega dependence and volume fraction phi dependence of the complex shear modulus G*(omega,phi) of monodisperse emulsions which have been concentrated by an osmotic pressure Pi. At a given phi, the elastic storage modulus G'(omega)=Re[G*(omega)] exhibits a low-frequency plateau G'(p), dominating the dissipative loss modulus G''(omega)=Im[G*(omega)] which exhibits a minimum. Above a critical packing fraction phi(c), we find that both Pi(phi) and G'(p)(phi) increase quasilinearly, scaling as (phi-phi(c))(mu), where phi(c) approximate to phi(c)(rcp), the volume fraction of a random close packing of spheres, and mu is an exponent close to unity. To explain this result, we develop a model of disordered droplets which interact through an effective repulsive anharmonic potential, based on results obtained for a compressed droplet. A simulation based on this model yields a calculated static shear modulus G and osmotic pressure Pi that are in excellent agreement with the experimental values of G'(p) and Pi.