Origins of Yielding and Viscoelasticity in Highly Concentrated, Gelled Colloidal Suspensions: An Experimental Study of Microstruture and Rheology

本文将对高浓度胶体悬浮液的屈服应力和粘弹性的微观结构来源进行研究。颗粒间的作用力导致胶凝、线性粘弹性和屈服。最新的基于絮凝、渗流和分维的模型将在它们经历屈服转变和剪切时，使用模型胶体悬浮液的小角度和广角光散射方法进行实验测试。对于体积分数在0.02到0.2之间的金属氧化物颗粒(不同长宽比的球体和棒体)在有机和水溶液中的近折射率匹配悬浮液将进行研究。该项目将检查在屈服之前因应变而导致的悬架结构变化。得到微观结构现象与宏观流变行为之间的联系。所提出的工作对陶瓷、磁存储介质和涂层制造中的胶体悬浮液的处理具有重要意义。

Abstract9813824M.J. Solomon, U. of MichiganThe microstructural origins of the yield stress and viscoelasticity in highly concentrated colloidal suspensions will be investigated. The interparticle forces give rise to gelation, linear viscoelasticity and yielding. Recent models based on flocculation, percolation and fractals will be experimentally tested using the small and wide-angle light scattering methods of model colloidal suspensions as they undergo yielding transition and shear. Nearly refractive index matched suspensions of metal oxide particles (spheres and rods of variable aspect ratios) in both organic and aqueous solvent will be investigated for volume fractions between 0.02 and 0.2. The project will examine the strain-induced changes in structure of the suspension just prior to yielding. A connection between the microstructural phenomena and macroscopic rheological behavior will be obtained. The proposed work has relevance in processing of colloidal suspensions in the manufacture of ceramics, magnetic storage media and coatings.