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Confocal Imaging of Confined Quiescent and Flowing Colloid-polymer Mixtures
Published on: May 21, 2014
Characterization of a Polydisperse Depletion-Flocculated Emulsion
Manoj1, Fillery-Travis, Watson
1Institute of Food Research, Norwich Research Park, Colney, Norwich, Norfolk, NR4 7UA, United Kingdom
Journal of Colloid and Interface Science
|August 5, 2000
Summary
Adding hydroxy-ethylcellulose polymer to oil-in-water emulsions creates a robust, stress-bearing network. Rheological measurements reveal this structure forms due to depletion interactions, not diffusion.
Area of Science:
- Colloid and Surface Science
- Rheology
- Materials Science
Background:
- Non-adsorbing polymers induce flocculation in emulsions.
- This flocculation can lead to the formation of space-spanning networks.
- Understanding the rheological properties of these networks is crucial for applications.
Purpose of the Study:
- To investigate the rheological properties of alkane-in-water emulsions flocculated by hydroxy-ethylcellulose.
- To characterize the structure and strength of the resulting polymer-induced network.
- To explore the relationship between network properties and oil/polymer concentrations.
Main Methods:
- Rheological measurements, specifically small-deformation oscillatory tests.
- Characterization of emulsion structure during network formation.
- Analysis of viscous and elastic moduli across a frequency range (0.01-10 Hz).
Main Results:
- Emulsions with polymer exhibited significant elastic modulus, unlike polymer-free emulsions or polymer solutions.
- Elastic modulus depended on oil and polymer concentrations, attributed to depletion interactions.
- Power-law relationships were observed between elastic modulus, strain limit, and oil fraction, but with deviations from fractal models.
- Modulus increased exponentially with polymer concentration; strain limit was independent of polymer.
Conclusions:
- Hydroxy-ethylcellulose addition transforms emulsions into viscoelastic networks via depletion interactions.
- The observed power-law relationships and fractal dimensionalities suggest complex network formation mechanisms.
- Network formation kinetics were not diffusion-controlled, indicating alternative aggregation pathways.
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