Pal R
Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
J Colloid Interface Sci. 2000 Dec 1;232(1):50-63. doi: 10.1006/jcis.2000.7185.
The linear viscoelastic behavior of polymer-thickened oil-in-water emulsions, polymer-thickened solids-in-liquid suspensions, and their blends is investigated using a controlled-stress rheometer. The emulsions exhibit a predominantly viscous behaviour at low values of oil concentration in that the loss modulus (G") exceeds the storage modulus (G') over most of the frequency range. At high values of oil concentration, the emulsions exhibit a predominantly elastic behavior. The ratio of storage modulus to loss modulus (G'/G") increases with the increase in oil concentration. Emulsions follow the theoretical model of J. F. Palierne (1990, Rheol. Acta 29, 204) only at low values of oil volume fraction (</=0.176). At high values of oil volume fraction, the Palierne model underpredicts the linear viscoelastic properties of emulsions. Polymer-thickened suspensions are predominantly viscous in nature; G">/=G' over most of the frequency range. The ratio G'/G" varies only slightly with the increase in solids volume fraction. The Palierne model describes the linear viscoelastic properties of suspensions accurately only at low values of solids volume fraction. At high values of solids concentration, the Parlierne model underpredicts the linear viscoelastic properties of suspensions and the deviation increases with the increase in solids concentration. The blends of emulsions and suspensions exhibit strong synergistic effects at low to moderate values of frequencies; the plots of blend modulus versus emulsion content exhibit a minimum. However, at high values of frequency, the blend modulus generally falls between the moduli of pure suspension and pure emulsion. The high-frequency modulus data of blends of emulsions and suspensions are successfully correlated in terms of the modulus ratio versus volume fraction of solids, where modulus ratio is defined as the ratio of blend modulus to pure emulsion modulus at the same frequency. Copyright 2000 Academic Press.
使用控制应力流变仪研究了聚合物增稠的水包油乳液、聚合物增稠的液固悬浮液及其混合物的线性粘弹性行为。在低油浓度下，乳液主要表现出粘性行为，即在大部分频率范围内，损耗模量（G"）超过储能模量（G'）。在高油浓度下，乳液主要表现出弹性行为。储能模量与损耗模量之比（G'/G"）随油浓度的增加而增加。乳液仅在低油体积分数（≤0.176）时符合J. F. 帕利埃恩（1990年，《流变学学报》29卷，204页）的理论模型。在高油体积分数下，帕利埃恩模型低估了乳液的线性粘弹性特性。聚合物增稠的悬浮液本质上主要是粘性的；在大部分频率范围内，G">≥G'。G'/G" 随固体体积分数的增加仅略有变化。帕利埃恩模型仅在低固体体积分数时准确描述悬浮液的线性粘弹性特性。在高固体浓度下，帕利埃恩模型低估了悬浮液的线性粘弹性特性，且偏差随固体浓度的增加而增大。乳液和悬浮液的混合物在低至中等频率值时表现出强烈的协同效应；混合物模量与乳液含量的关系图呈现最小值。然而，在高频率值时，混合物模量通常介于纯悬浮液和纯乳液的模量之间。乳液和悬浮液混合物的高频模量数据根据模量比与固体体积分数成功关联，其中模量比定义为相同频率下混合物模量与纯乳液模量之比。版权所有2000年学术出版社。
