论文标题
通过调谐粒子间摩擦，将屈服压力悬浮液变成剪切厚的悬浮液
Turning a yield-stress calcite suspension into a shear-thickening one by tuning inter-particle friction
论文作者
论文摘要
我们表明，在甘油 - 水混合物中非棕色方解石颗粒的悬浮液可以通过添加各种表面活性剂的添加而连续调节从作为屈服压力悬浮液到剪切厚的悬浮液（而无需可测量的屈服应力）。我们在最新的理论框架内解释了我们的结果，该框架模拟了应激依赖性约束对粒子间运动的流变学影响。发现裸露的方解石颗粒悬浮液具有有限的屈服应力。在这些悬浮液中，在无限施加的应力下约束颗粒间滑动形式的摩擦接触并在此之后保持，而随着施加的应力的增加，限制颗粒间旋转的粘合键被打破。添加表面活性剂可减少此类悬浮液的屈服应力。我们表明，与添加到胶体悬浮液中的表面活性剂的情况相反，在非棕色悬浮液中的这种效果归因于出现有限发作应力以形成摩擦接触。我们的数据表明，这种发作应力的幅度是通过表面活性剂吸附到颗粒表面的强度来确定的，因此，这构成了使用表面活性剂来调整由粘合剂非棕色颗粒悬浮液的制剂的流变性的新设计原理。
We show that a suspension of non-Brownian calcite particles in glycerol-water mixtures can be tuned continuously from being a yield-stress suspension to a shear-thickening suspension--without a measurable yield stress--by the addition of various surfactants. We interpret our results within a recent theoretical framework that models the rheological effects of stress-dependent constraints on inter-particle motion. Bare calcite particle suspensions are found to have finite yield stresses. In these suspensions, frictional contacts that constrain inter-particle sliding form at an infinitesimal applied stress and remain thereafter, while adhesive bonds that constrain inter-particle rotation are broken as the applied stress increases. Adding surfactants reduces the yield stress of such suspensions. We show that, contrary to the case of surfactant added to colloidal suspensions, this effect in non-Brownian suspensions is attributable to the emergence of a finite onset stress for the formation of frictional contacts. Our data suggest that the magnitude of this onset stress is set by the strength of surfactant adsorption to the particle surfaces, which therefore constitutes a new design principle for using surfactants to tune the rheology of formulations consisting of suspensions of adhesive non-Brownian particulates.
