Quantifying the dispersion quality of partially aggregated colloidal dispersions by high frequency rheology
OPEN ACCESS
Loading...
Author / Producer
Date
2017-11
Publication Type
Journal Article
ETH Bibliography
yes
Citations
Altmetric
OPEN ACCESS
Data
Rights / License
Abstract
An important parameter for the performance of nanomaterials is the degree by which the nanoparticles are dispersed in a matrix. Optical microscopy or scattering methods are useful to characterise the state of dispersion, but are not generally applicable to all materials. Electron microscopy methods are laborious in preparation and typically offer only quantitative information on a very local scale. In the present work we investigate how high frequency rheological measurements can be used for partially dispersed suspensions at intermediate to higher particle loadings, even for high viscous matrices. Although the contribution of the particles is particularly visible in the low frequency linear viscoelastic behaviour, a more direct relationship between rheological properties and degree of dispersion can be derived from the loss modulus in the high frequency limit. To this end, a home-built piezo shear rheometer is constructed to extend the frequency range typically accessible by commercial rotational rheometers. Measurements on spherical silica particles, with a varying degree of dispersion in low molecular weight PDMS, are used to demonstrate how high frequency rheometry can be used to quantify dispersion quality. The linear viscoelastic properties are compared to analytical scaling theories to demonstrate that a hydrodynamically dominated regime is reached. The dependence of the relative high frequency loss modulus on volume fraction is then compared to predictions of a hydrodynamic viscosity model for the derivation of a dispersion quality index. It is used to follow the evolution of the dispersion quality as a function of mixing time and consumed power.
Permanent link
Publication status
published
External links
Editor
Book title
Journal / series
Volume
13 (43)
Pages / Article No.
7897 - 7906
Publisher
Royal Society of Chemistry
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Soft Matter; rheology; Dispersions; SUSPENSIONS (HYDRODYNAMICS)
Organisational unit
09482 - Vermant, Jan / Vermant, Jan
Notes
Funding
157147 - Exploiting particle shape and connectivity to interrogate flocculated suspension mechanics. (SNF)