The effective viscosity of nanoparticle dispersions has been investigated experimentally quite a lot and various behaviours have been observed. Many models have been proposed to predict the effective viscosity, but these are mainly empirical ones, correlations with a tuning parameter or based on fastidious molecular interactions simulations. In this work, we propose a new fully physics-based analytical expression for the effective viscosity implementing theories from extended thermodynamics, including nano-confinement effects, nanoparticle–fluid interactions, density effects, size effects and nanoparticle volume fraction. We validate this model against several different types of nanoparticle dispersions and emulsions and explain the different behaviours using the same model. It appears that the density ratio of the nanoparticles with respect to the fluid plays a crucial role affecting the viscosity. The nanoparticle–fluid interactions become increasingly important for smaller nanoparticle sizes. From these comparisons, we arrive at a general simplified expression for the effective viscosity of nanoparticle dispersions, where it is observed that there is a direct universal relation between the nanoparticles and fluid densities and the nanodispersion viscosities. The validity of such a relation has been explicitly demonstrated.

中文翻译：

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纳米颗粒和稳定乳液分散体的密度和粘度之间的通用关系。

纳米颗粒分散体的有效粘度已通过实验进行了大量研究，并已观察到各种行为。已经提出了许多模型来预测有效粘度，但是这些模型主要是经验模型，与调节参数的相关性或基于精妙的分子相互作用模拟。在这项工作中，我们从扩展的热力学中为有效的粘度实现理论提出了一种新的完全基于物理学的解析表达式，包括纳米约束效应，纳米粒子与流体的相互作用，密度效应，尺寸效应和纳米粒子体积分数。我们针对几种不同类型的纳米颗粒分散体和乳液验证了该模型，并使用同一模型解释了不同的行为。似乎纳米颗粒相对于流体的密度比在影响粘度方面起着至关重要的作用。对于较小的纳米颗粒，纳米颗粒与流体的相互作用变得越来越重要。从这些比较中，我们得出了纳米颗粒分散体有效粘度的一般简化表达式，其中观察到纳米颗粒与流体密度和纳米分散体粘度之间存在直接的通用关系。已经明确证明了这种关系的有效性。观察到纳米颗粒与流体密度和纳米分散体粘度之间存在直接的通用关系。已经明确证明了这种关系的有效性。观察到纳米颗粒与流体密度和纳米分散体粘度之间存在直接的通用关系。已经明确证明了这种关系的有效性。