Dilatancy in the flow and fracture of stretched colloidal suspensions
Dilatancy in the flow and fracture of stretched colloidal suspensions
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DOI：
10.1038/ncomms1119
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发表时间：
2010-11-01
影响因子：
16.6
通讯作者：
Bertola, V.
中科院分区：
文献类型：
--
作者：
Smith, M. I.;Besseling, R.;Bertola, V.
浓缩颗粒悬浮液在制药、化妆品和食品行业中很常见，表现出耐人寻味的流变性。特别是，粘度随应变率的急剧增加(剪切增稠和堵塞)，这在高体积分数时经常观察到，具有实际和基本的重要性。然而，这些产品的制造及其随后的分配通常涉及与简单剪切流动实验本质上不同的流动几何。在这项研究中，我们证明了胶体流体的细丝在拉伸载荷下的伸长和断裂与其剪切流变学中所看到的堵塞转变密切相关。然而，修改后的流动几何形状显示了重要的附加效应。使用一个具有近乎核心相互作用的模型系统，我们提供了在这种受拉伸的胶体流体中具有令人惊讶的强大粘弹性的证据。通过高速摄影，我们还可以直接观察到膨胀和造粒效应，这些效应会导致断裂超过临界延伸率。
Concentrated particulate suspensions, commonplace in the pharmaceutical, cosmetic and food industries, display intriguing rheology. In particular, the dramatic increase in viscosity with strain rate (shear thickening and jamming), which is often observed at high-volume fractions, is of practical and fundamental importance. Yet, manufacture of these products and their subsequent dispensing often involves flow geometries substantially different from that of simple shear flow experiments. In this study, we show that the elongation and breakage of a filament of a colloidal fluid under tensile loading is closely related to the jamming transition seen in its shear rheology. However, the modified flow geometry reveals important additional effects. Using a model system with nearly hard-core interactions, we provide evidence of surprisingly strong viscoelasticity in such a colloidal fluid under tension. With high-speed photography, we also directly observe dilatancy and granulation effects, which lead to fracture above a critical elongation rate.