Rheological behavior of silica suspensions in aqueous solutions of associating polymer

Associating polymers are hydrophilic long-chain molecules containing a small amount of hydrophobic groups. The aqueous solutions show viscoelastic responses above some critical concentrations because a three-dimensional structure is formed by association of hydrophobic groups. When the associating p...

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Bibliographic Details
Published in:Colloid and polymer science 2008-11, Vol.286 (13), p.1537-1544
Main Authors: Saito, Y., Ogura, H., Otsubo, Y.
Format: Article
Language:English
Subjects:
Applied sciences
Aqueous solutions
Atoms & subatomic particles
Bridging
Chains (polymeric)
Characterization and Evaluation of Materials
Chemistry
Chemistry and Materials Science
Complex Fluids and Microfluidics
Exact sciences and technology
Flocculating
Food Science
Nanotechnology and Microengineering
Networks
Organic polymers
Original Contribution
Physical Chemistry
Physicochemistry of polymers
Polymer Sciences
Polymers
Properties and characterization
Silicon dioxide
Soft and Granular Matter
Solution and gel properties
Surface chemistry
Viscosity
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Summary:Associating polymers are hydrophilic long-chain molecules containing a small amount of hydrophobic groups. The aqueous solutions show viscoelastic responses above some critical concentrations because a three-dimensional structure is formed by association of hydrophobic groups. When the associating polymers are added to silica suspensions at low concentrations, the flocculation is induced by bridging mechanisms, and the flow of suspensions become shear-thinning. For suspensions prepared with polymer solutions in which the associating network is developed, the viscosity decreases, shows a minimum, and then increases with increasing particle concentration. The viscosity decrease may arise from the breakdown of associating network due to adsorption of polymer chains onto the silica surfaces. As the particle concentration is increased, the polymer concentration in solution is decreased, and finally, all polymer chains are adsorbed on the surfaces. Beyond this point, the partial coverage of particle surfaces takes place and strong interactions are generated between particles by polymer bridging. Since the stable suspensions are converted to highly flocculated systems, the viscosity is increased and the flow becomes shear-thinning. The concentration effect of silica particles on the viscosity behavior of suspensions can be explained by a combination of viscosity decrease in solution due to polymer adsorption and viscosity increase due to flocculation.
ISSN:0303-402X
1435-1536
DOI:10.1007/s00396-008-1928-5