论文标题
流变学在乳液中发现独特的玻璃和干扰过渡
Rheology finds distinct glass and jamming transitions in emulsions
论文作者
论文摘要
我们研究具有各种液滴尺寸（1 $μ$ m -2 $μ$ m直径）的单分散和bidisperse乳液的流变学。在关键体积分数$ ϕ_c $之上，这些系统表现出固体的行为，并且可以检测到屈服应力。先前的实验表明，对于小热颗粒，流变学将在$ ϕ_c = ϕ_g = 0.58 $下看到玻璃转变；对于大型Athermal系统，流变学将在$ ϕ_c = ϕ_j = 0.64 $下看到干扰过渡。然而，模拟指出，在热和阿特尔马尔方案的跨界时，在同一样品中均可观察到玻璃和干扰过渡。在这里，我们通过剪切四个带有流变仪的水中乳液来进行实验。我们可以观察到较小直径的液滴的玻璃和干扰过渡，并且仅对较大的直径液滴进行了干扰过渡。 bidisperse样品的行为与小滴样品样本相似，观察到了两个过渡。我们的流变数据是Herschel-Bulkley模型和三个组件模型都非常合适的。基于拟合参数，我们的原始流变数据不会崩溃到主曲线上。我们的结果表明，分散体中的液固化过渡可能不是通用的，而是取决于粒子类型。
We study the rheology of monodisperse and bidisperse emulsions with various droplet sizes (1 $μ$m -- 2 $μ$m diameter). Above a critical volume fraction $ϕ_c$, these systems exhibit solid-like behavior and a yield stress can be detected. Previous experiments suggest that for small thermal particles, rheology will see a glass transition at $ϕ_c = ϕ_g =0.58$; for large athermal systems, rheology will see a jamming transition at $ϕ_c = ϕ_J =0.64$. However, simulations point out that at the crossover of thermal and athermal regimes, the glass and jamming transitions may both be observed in the same sample. Here we conduct an experiment by shearing four oil-in-water emulsions with a rheometer. We observe both a glass and a jamming transition for our smaller diameter droplets, and only a jamming transition for our larger diameter droplets. The bidisperse sample behaves similarly to the small droplet sample, with two transitions observed. Our rheology data are well-fit by both the Herschel-Bulkley model and the Three Component model. Based on the fitting parameters, our raw rheological data would not collapse onto a master curve. Our results suggest that liquid-solid transitions in dispersions may not be universal, but depend on particle type.
