A Structural Model of Hydrophobically Modified Urethane−Ethoxylate (HEUR) Associative Polymers in Shear Flows

1998 ◽  
Vol 31 (13) ◽  
pp. 4149-4159 ◽  
Author(s):  
K. C. Tam ◽  
R. D. Jenkins ◽  
M. A. Winnik ◽  
D. R. Bassett
Keyword(s):  
Shear Flows ◽  
Structural Model ◽  
Associative Polymers ◽  
Hydrophobically Modified

Solution rheology of hydrophobically modified associative polymers: Effects of backbone composition and hydrophobe concentration

2004 ◽  
Vol 48 (5) ◽  
pp. 979-994 ◽  
Author(s):  
Ahmed A. Abdala ◽  
Wenjun Wu ◽  
Keith R. Olesen ◽  
Richard D. Jenkins ◽  
Alan E. Tonelli ◽  
...  
Keyword(s):  
Associative Polymers ◽  
Hydrophobically Modified ◽  
Solution Rheology

Dynamics of Erythrocytes in Oscillatory Shear Flows: Effects of S/V Ratio

Soft Matter ◽  
2022 ◽  
Author(s):  
Qiang Zhu ◽  
Xiaobo Bi
Keyword(s):  
Dynamic Response ◽  
Integral Method ◽  
Shear Flows ◽  
Structural Model ◽  
Interaction Model ◽  
Cell Interaction ◽  
Boundary Integral ◽  
Oscillatory Shear ◽  
Boundary Integral Method ◽  
Fluid Cell

By combining a multiscale structural model of erythrocyte with a fluid-cell interaction model based on the boundary-integral method, we numerically investigate the dynamic response of erythrocytes in oscillatory shear flows...

Influence of hydrophobe fraction content on the rheological properties of hydrosoluble associative polymers obtained by micellar polymerization

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Enrique J. Jiménez-Regalado ◽  
Elva B. Hernández-Flores
Keyword(s):  
Relaxation Time ◽  
Rheological Properties ◽  
Polymer Concentration ◽  
Water Soluble ◽  
Polymer Chains ◽  
Associative Polymers ◽  
Hydrophobically Modified ◽  
Viscosity Increase ◽  
Increase Rate ◽  
Micellar Polymerization

AbstractThe synthesis, characterization and rheological properties in aqueous solutions of water-soluble associative polymers (AP’s) are reported. Polymer chains consisting of water-soluble polyacrylamides, hydrophobically modified with low amounts of N,N-dihexylacrylamide (1, 2, 3 and 4 mol%) were prepared via free radical micellar polymerization. The properties of these polymers, with respect to the concentration of hydrophobic groups, using steady-flow and oscillatory experiments were compared. An increase of relaxation time (TR) and modulus plateau (G0) was observed in all samples studied. Two different regimes can be clearly distinguished: a first unentangled regime where the viscosity increase rate strongly depends on hydrophobic content and a second entangled regime where the viscosity follows a scaling behavior of the polymer concentration with an exponent close to 4.

scholarly journals Influence of Hydrophobe, Surfactant and Salt Concentrations in Hydrophobically Modified Alkali-Soluble Polymers Obtained by Solution Polymerization

2017 ◽  
Vol 56 (2) ◽  
Author(s):  
Enrique Javier Jiménez Regalado ◽  
Claudia Cecilia Rivera Vallejo ◽  
Hortensia Maldonado Textle ◽  
Ramiro Guerrero ◽  
Jorge Félix Espinosa Muñoz
Keyword(s):  
Aqueous Solution ◽  
Sodium Dodecyl Sulfate ◽  
Electrostatic Interactions ◽  
Sodium Dodecyl ◽  
Solution Polymerization ◽  
Soluble Polymers ◽  
Associative Polymers ◽  
Hydrophobically Modified ◽  
Modified Polymers ◽  
Hydrophobically Modified Polymers

The viscosity of hydrophobically modified alkali-soluble polymers to different hydrophobic macromonomer concentrations in the presence of various concentrations of anionic surfactant and salt were investigated. Associative polymers containing both ionic sites and small number of hydrophobic groups were prepared, and their thickening properties in aqueous solution were investigated. Solution polymerization was used for obtained the different polymers. Relationships between hydrophobe, sodium dodecyl sulfate (SDS) and salt (NaCl) concentrations are proposed. Owing to the competition between attractive hydrophobic interaction and repulsive electrostatic interactions, such hydrophobically modified polymers exhibit various rheological behaviors in aqueous solution depending on hydrophobic macromonomer, SDS and NaCl concentrations.

Stability of the tank treading modes of erythrocytes and its dependence on cytoskeleton reference states

2015 ◽  
Vol 771 ◽  
pp. 449-467 ◽  
Author(s):  
Zhangli Peng ◽  
Sara Salehyar ◽  
Qiang Zhu
Keyword(s):  
Capillary Number ◽  
Shear Flows ◽  
Structural Model ◽  
Viscosity Ratio ◽  
Reference State ◽  
Central Plane ◽  
Cell Dynamics ◽  
Mode 2 ◽  
Linear Shear ◽  
A Cell

We studied the tank treading motion of an erythrocyte (red blood cell, or RBC) in linear shear flows by using a boundary-element fluid-dynamics model coupled with a multiscale structural model of the cell. The purpose was to investigate the correlation between the reference (stress-free) state of the cytoskeleton and the cell dynamics in shear flows with relatively high capillary numbers. We discovered that there exist two distinctive modes of tank treading, mode 1 and mode 2. In mode 1 the membrane elements originating from the dimple areas keep close to the central plane, whereas in mode 2 these elements remain near the farthermost locations from the central plane. Mode 1 is also characterized by significantly higher breathing and swinging oscillations. During tank treading one mode may become unstable and switch to the other. Their stability depends on the viscosity ratio and the capillary number. At a fixed viscosity ratio, when the capillary number is increased the cell experiences sequentially a region dominated by mode 2, a mode 1/mode 2 bistable region and a region dominated by mode 1. More profoundly, these regions are highly sensitive to the reference state of the cytoskeleton. For example, compared with a cell with a biconcave reference state, a cell with a spheroidal reference state features a much smaller region dominated by mode 2. This finding may guide experiments to identify the actual reference state of these cells.

Structure-property relations of liquid crystalline polymers

1987 ◽  
Vol 45 ◽  
pp. 460-463
Author(s):  
Linda C. Sawyer
Keyword(s):  
Solid State ◽  
Liquid Crystalline ◽  
Structural Model ◽  
Crystalline Polymer ◽  
Liquid Crystalline Polymers ◽  
Mechanical Anisotropy ◽  
Structure Property ◽  
Preparation Methods ◽  
Crystalline Polymers ◽  
Extended Chain

Recent liquid crystalline polymer (LCP) research has sought to define structure-property relationships of these complex new materials. The two major types of LCPs, thermotropic and lyotropic LCPs, both exhibit effects of process history on the microstructure frozen into the solid state. The high mechanical anisotropy of the molecules favors formation of complex structures. Microscopy has been used to develop an understanding of these microstructures and to describe them in a fundamental structural model. Preparation methods used include microtomy, etching, fracture and sonication for study by optical and electron microscopy techniques, which have been described for polymers. The model accounts for the macrostructures and microstructures observed in highly oriented fibers and films.Rod-like liquid crystalline polymers produce oriented materials because they have extended chain structures in the solid state. These polymers have found application as high modulus fibers and films with unique properties due to the formation of ordered solutions (lyotropic) or melts (thermotropic) which transform easily into highly oriented, extended chain structures in the solid state.

The Hierarchic Order of Intermediate Filament Structure and Assembly

1985 ◽  
Vol 43 ◽  
pp. 722-725
Author(s):  
U. Aebi ◽  
E.C. Glavaris ◽  
R. Eichner
Keyword(s):  
Tissue Specificity ◽  
Structural Model ◽  
Eukaryotic Cells ◽  
Cdna Sequencing ◽  
Filament Structure ◽  
Keratin Filaments ◽  
Isoelectric Points ◽  
Immunological Crossreactivity

Five different classes of intermediate-sized filaments (IFs) have been identified in differentiated eukaryotic cells: vimentin in mesenchymal cells, desmin in muscle cells, neurofilaments in nerve cells, glial filaments in glial cells and keratin filaments in epithelial cells. Despite their tissue specificity, all IFs share several common attributes, including immunological crossreactivity, similar morphology (e.g. about 10 nm diameter - hence ‘10-nm filaments’) and the ability to reassemble in vitro from denatured subunits into filaments virtually indistinguishable from those observed in vivo. Further more, despite their proteinchemical heterogeneity (their MWs range from 40 kDa to 200 kDa and their isoelectric points from about 5 to 8), protein and cDNA sequencing of several IF polypeptides (for refs, see 1,2) have provided the framework for a common structural model of all IF subunits.

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