Viscosity Model for Nanoparticulate Suspensions Based on Surface Interactions.

Benedikt Finke,Arno Kwade,Clara Sangrós Giménez,Carsten Schilde

doi:10.3390/ma14112752

Benedikt Finke, Arno Kwade + Show 2 more

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https://doi.org/10.3390/ma14112752

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Journal: Materials	Publication Date: May 23, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Technische Universität Braunschweig

Abstract

In this paper, a widely mechanistic model was developed to depict the rheological behaviour of nanoparticulate suspensions with solids contents up to 20 wt.%, based on the increase in shear stress caused by surface interaction forces among particles. The rheological behaviour is connected to drag forces arising from an altered particle movement with respect to the surrounding fluid. In order to represent this relationship and to model the viscosity, a hybrid modelling approach was followed, in which mechanistic relationships were paired with heuristic expressions. A genetic algorithm was utilized during model development, by enabling the algorithm to choose among several hard-to-assess model options. By the combination of the newly developed model with existing models for the various physical phenomena affecting viscosity, it can be applied to model the viscosity over a broad range of solids contents, shear rates, temperatures and particle sizes. Due to its mechanistic nature, the model even allows an extrapolation beyond the limits of the data points used for calibration, allowing a prediction of the viscosity in this area. Only two parameters are required for this purpose. Experimental data of an epoxy resin filled with boehmite nanoparticles were used for calibration and comparison with modelled values.

Highlights

Since Einstein’s pioneering work in 1906 [1,2], an abundance of viscosity models have proven the necessity and difficulty of describing the rheological behaviour of suspensions.With the emergence of nano-materials, this field of research has been extended by the need to account for the rheological phenomena caused by nanoparticles immersed in a fluid [3,4].The production process of nanoparticle suspensions is a typical case in which a viscosity model can be required
The viscosity model relied on several parameters, which determined the resolution of the force evaluation with respect to the distance (δ) and the width of the particle size fractions (∆x)
A viscosity model was developed, which described the rheological behaviour of nanoparticulate suspensions with respect to solids content, shear rate, temperature and particle size, but even allowed an extrapolation far beyond the range of values used for its calibration

Summary

Introduction

Since Einstein’s pioneering work in 1906 [1,2], an abundance of viscosity models have proven the necessity and difficulty of describing the rheological behaviour of suspensions. The production process of nanoparticle suspensions is a typical case in which a viscosity model can be required. During the production of nanoparticle-filled polymers via dispersing of the particles in a resin, the production process itself strongly depends on the viscosity [5]. This is because the viscosity influences the level of stress on the particles during the process. The changes in particle size during the process cause the viscosity to change, which influences the stress level and the process

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