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Rheology and flow dynamics of wormlike micellar gels Gupta, Ronak Rajesh
Abstract
Long-chained zwitterionic surfactants form wormlike micellar (WLM) gels in solution at room temperature and revert back to a Maxwell viscoelasticity at higher temperatures. We study the rheology and flow dynamics of such WLM gels using a combination of rheometry and flow experiments. First, we rheologically characterize the material and reveal details of its microstructure along with signatures of shear-induced fracture and banding. Then we pump these WLM gels in a capillary pipe and measure the development of velocity profiles in time. Our experiments capture flow features like strong slip, plug and shear layers along with flow-induced heterogeneity. In the third part of the thesis we study droplet detachment and filament thinning of our WLM gels. We show the existence of elastocapillary thinning regimes, power-law failure and discuss dependencies of said dynamics on surfactant concentration. Our experiments reveal hitherto unknown complex dynamics even in simple flows of WLM gels and is likely to inform research on flows where rheology and transient fluid dynamics of similar soft matter systems play a crucial role.
Item Metadata
Title |
Rheology and flow dynamics of wormlike micellar gels
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Creator | |
Supervisor | |
Publisher |
University of British Columbia
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Date Issued |
2023
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Description |
Long-chained zwitterionic surfactants form wormlike micellar (WLM) gels in solution
at room temperature and revert back to a Maxwell viscoelasticity at higher
temperatures. We study the rheology and flow dynamics of such WLM gels using
a combination of rheometry and flow experiments. First, we rheologically characterize
the material and reveal details of its microstructure along with signatures of
shear-induced fracture and banding. Then we pump these WLM gels in a capillary
pipe and measure the development of velocity profiles in time. Our experiments
capture flow features like strong slip, plug and shear layers along with flow-induced
heterogeneity. In the third part of the thesis we study droplet detachment and filament
thinning of our WLM gels. We show the existence of elastocapillary thinning
regimes, power-law failure and discuss dependencies of said dynamics on surfactant
concentration. Our experiments reveal hitherto unknown complex dynamics
even in simple flows of WLM gels and is likely to inform research on flows where
rheology and transient fluid dynamics of similar soft matter systems play a crucial
role.
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Genre | |
Type | |
Language |
eng
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Date Available |
2023-04-25
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0431414
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2023-11
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivatives 4.0 International