Abstract Wall slip or, more usually, liquid-solid phase separation at the boundary wall when measuring the rheological properties of particulate suspensions is normally considered an undesirable source of error. However, exclusion of a structure consisting of multiple particulates at a planar boundary can, in turn, reveal the nature of that structure and the way it interacts with other elements in the dispersion. Using a system of surface-treated ground calcite particles, designed to control lyophilicity, dispersed, respectively, in two comparative liquids, hexadecane (dispersive surface tension component only) and linseed oil (both dispersive and polar surface tension components), the relative wettability of the particulate surface can be studied. The static state is viscoelastic, with the elastic component reflecting the network of interacting forces acting to structure the particles together and/or to trap liquid within the long-range particle-particle matrix. As strain is applied under plate-plate geometry, selected aggregate structures become size-excluded at the wall, leading to a loss of shear coupling with the bulk polydisperse suspension. At high strain, given optimal solids content, this results in a stochastic transition between two discrete stress data sets, i.e. that with full shear coupling and that with only partial coupling. Stress recovery is subsequently monitored as strain is step-wise reduced, and the progress toward loss of the stochastic transient phenomenon, together with its parallel change in magnitude, is used to describe the re-formation of primary agglomerates. Cessation of the phase separation indicates re-build of the close-to-static structure. Under certain conditions it is observed that the cessation may be accompanied by a secondary relaxation of state, indicating the build of a secondary but weaker structure, likened to the well-known dual-level flocculation in aqueous colloidal suspension. Rheo-optical observations using small angle light scattering illumination (SALS) are used to confirm a structure model switching from static (uncoupled with shear) to rotating (fully coupled to the boundary-defined shear) and finally uniformly sheared.

中文翻译：

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随机瞬态液固相分离揭示悬浮液中颗粒的多级分散状态

摘要 当测量颗粒悬浮液的流变特性时，壁滑移或更常见的是边界壁处的液固相分离通常被认为是不希望的误差来源。然而，在平面边界处排除由多个颗粒组成的结构可以反过来揭示该结构的性质以及它与分散体中其他元素相互作用的方式。使用表面处理过的方解石颗粒系统，旨在控制亲液性，分别分散在两种比较液体，十六烷（仅分散表面张力成分）和亚麻籽油（分散和极性表面张力成分）中，相对润湿性可以研究颗粒表面。静态是粘弹性的，弹性分量反映了相互作用力的网络，作用是将颗粒结构在一起和/或将液体捕获在长程颗粒-颗粒基质内。当应变在板-板几何结构下施加时，选定的聚集体结构在壁上变得大小不一，导致与散装多分散悬浮液的剪切耦合损失。在高应变下，给定最佳固体含量，这会导致两个离散应力数据集之间的随机过渡，即具有完全剪切耦合的数据集和仅具有部分耦合的数据集。随着应变逐步减小，应力恢复随后被监测，随机瞬态现象消失的进展及其幅度的平行变化被用来描述初级附聚物的重新形成。相分离的停止表明接近静态结构的重建。在某些条件下，观察到停止可能伴随着状态的二次弛豫，表明二次但较弱的结构的建立，类似于众所周知的水性胶体悬浮液中的双级絮凝。使用小角度光散射照明 (SALS) 的流变光学观测用于确认结构模型从静态（与剪切不耦合）切换到旋转（完全耦合到边界定义的剪切）并最终均匀剪切。类似于众所周知的水性胶体悬浮液中的双级絮凝。使用小角度光散射照明 (SALS) 的流变光学观测用于确认结构模型从静态（与剪切不耦合）切换到旋转（完全耦合到边界定义的剪切）并最终均匀剪切。类似于众所周知的水性胶体悬浮液中的双级絮凝。使用小角度光散射照明 (SALS) 的流变光学观测用于确认结构模型从静态（与剪切不耦合）切换到旋转（完全耦合到边界定义的剪切）并最终均匀剪切。