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Shear influence on colloidal cluster growth: a SANS and USANS study
Chris Muzny1, Liliana de Campo2, Anna Sokolova2
1Applied Chemicals and Materials Division, National Institute of Standards and Technology, Boulder, CO 80305, USA.
Journal of Applied Crystallography
|October 4, 2023
Summary
Shear fields disrupt silica particle gelation, altering cluster size and viscosity. Small-angle scattering reveals microscopic changes, aiding theoretical models for sheared colloidal suspensions.
Area of Science:
- Colloid and Surface Science
- Materials Science
- Rheology
Background:
- Colloidal suspensions like silica/water can form gel networks.
- External forces, such as shear, can significantly alter the structure and properties of these gels.
- Understanding the interplay between gelation and shear is crucial for controlling material properties.
Purpose of the Study:
- To investigate the time evolution of silica/water clusters under shear during interrupted gelation.
- To understand the microscopic basis for viscosity changes in sheared colloidal gels.
- To provide structural data from scattering experiments to inform theoretical models.
Main Methods:
- Utilized an 8.3 nm particle silica solution (Ludox) with initiated gelation.
- Applied a Couette shear field at a constant shear rate of 250 s-1.
- Employed a unified small-angle neutron scattering (SANS) and ultra-small-angle neutron scattering (USANS) procedure to probe structures from nanometer to micrometer scales.
Main Results:
- Scattering data captured structural changes in colloidal clusters subjected to shear over time.
- Fitted time-dependent scattered intensity to estimate effective cluster volume fraction and size evolution.
- Demonstrated a link between structural changes and viscosity behavior in sheared colloidal suspensions.
Conclusions:
- Shear fields significantly impact the time evolution and structure of silica/water gel clusters.
- Scattering techniques provide essential structural insights into sheared colloidal systems.
- A theoretical framework can predict viscosity based on cluster volume fraction and size changes.
Keywords:
SANSUSANSapplied shearcolloidal silicamicrometre scaleretarded gelationsmall-angle neutron scatteringstructure factor derivationtime-dependent phenomenaultra-small-angle neutron scatteringviscosityvolume fractionMore Related Videos
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