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Dec 1982

Volume 26, Issue 6, pp. 499-614


Bounds and Estimates of Second Normal Stress Difference in Rectilinear Flow

V. O'Brien

J. Rheol. 26, 499 (1982); http://dx.doi.org/10.1122/1.549688 (13 pages)

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Although some mathematical bounds for the second normal stress in rectilinear rheological flows in semi‐infinite geometries have been demonstrated, and some closer estimates made by numerical simulation, the bound predictions and numerical estimates obtained in the present study are for more practical finite slotted ducts. Using a finite‐difference technique (previously shown for Newtonian flows in noncircular ducts) we simulate the steady velocity field due to a longitudinal pressure gradient and predict an average transverse pressure difference that must exist for an approximately second‐order fluid. This presumably measurable quantity is proportional to the second normal stress difference and thus offers a method to measure this rheological property, but it is likely to be very small. The numerical method can be extended to oscillatory linearly viscoelastic flows.
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47.50.-d Non-Newtonian fluid flows
47.11.-j Computational methods in fluid dynamics
83.10.Rs Computer simulation of molecular and particle dynamics
83.60.Bc Linear viscoelasticity

Analysis of the Tensile Behavior of Wheat Gluten at Constant Strain Rates. The Effect of Secondary Bonding Modification

Arturo E. Inda and Chokyun Rha

J. Rheol. 26, 513 (1982); http://dx.doi.org/10.1122/1.549675 (21 pages)

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The effect of secondary bonding on the tensile behavior of gluten at constant strain rate was studied. Freeze‐dried gluten was reconstituted with water, deuterium oxide, and 1M, 3M, and 5M aqueous solutions of urea. The tensile properties were measured at 23±1°C at strain rates from 4.77×10−4 to 4.77×10−1 s−1. Separation of time and strain effects was achieved up to Cauchy strains ranging from 0.43 to 2.86, depending on the medium used to reconstitute gluten. Both the stress relaxation modulus, calculated from the constant strain rate modulus, and the rate of stress relaxation were higher for gluten reconstituted with deuterium oxide than for gluten reconstituted with water. The stress relaxation modulus of gluten reconstituted with 1M urea was 30% lower than that of gluten reconstituted with water but the rate of stress relaxation was the same in both materials. As the concentration of urea increased, the stress relaxation rate decreased progressively while the stress relaxation modulus increased. These results are discussed in terms of changes in conformation and interactions resulting from the partial disruption or strengthening of secondary bonds caused by urea or deuterium oxide, respectively.
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87.14.E- Proteins
87.15.La Mechanical properties
83.80.Lz Physiological materials (e.g. blood, collagen, etc.)

A Continuum Theory of Smectic A Liquid Crystals

Goodarz Ahmadi

J. Rheol. 26, 535 (1982); http://dx.doi.org/10.1122/1.549676 (22 pages) | Cited 1 time

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The derivation of a continuum theory for smectic A liquid crystals is attempted. The thermodynamics of smectic A liquid crystals is investigated and a set of appropriate constitutive equations are derived. The equilibrium state of smectic A liquid crystals is studied and the explicit equations for smectodynamics are derived. Rectilinear plane flow of smectic liquid crystals is considered and some simple solutions are discussed. The problem of wave propagation is studied and the dispersion relations are obtained and discussed. The bending of smectic layer is also investigated.
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83.80.Xz Liquid crystals: nematic, cholesteric, smectic, discotic, etc.
83.10.Ff Continuum mechanics
47.50.-d Non-Newtonian fluid flows

Solvation Effects on Dilatancy in Concentrated PVC Plastisols

S. J. Willey and C. W. Macosko

J. Rheol. 26, 557 (1982); http://dx.doi.org/10.1122/1.549677 (8 pages)

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The effect of the strength of particle‐particle interactions on dilatancy was investigated in concentrated poly(vinyl chloride) (PVC) emulsion resin plastisols. Particle interactions were controlled by selection of a series of phthalate ester and mixed solvent suspending media. Solvent effects on the strength of interparticle interactions were interpreted in terms of steric stabilization theory. The flow strength required to effect dilatancy decreased as the solvent quality of the continuous phase was reduced.
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83.80.Hj Suspensions, dispersions, pastes, slurries, colloids
83.80.Iz Emulsions and foams
83.85.Cg Rheological measurements—rheometry
64.75.-g Phase equilibria

Notes: On the Prediction of the Primary Normal Stress Coefficient from Shear Viscosity

J. Stastna and D. de Kee

J. Rheol. 26, 565 (1982); http://dx.doi.org/10.1122/1.549678 (6 pages)

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Abstract Unavailable
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83.80.Rs Polymer solutions
83.80.Sg Polymer melts
47.11.-j Computational methods in fluid dynamics
83.10.Gr Constitutive relations

Abstracts from the 54th Annual Meeting of the Society of Rheology, Evanston, Illinois, October 24–28, 1982

J. Rheol. 26, 571 (1982); http://dx.doi.org/10.1122/1.549693 (44 pages)

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Abstract Unavailable
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83.00.00 Rheology
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