Viscosity, elasticity, and viscoelasticity

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Introduction

See also:

Viscosity, elasticity, and viscoelasticity from Lectures for AP225.

Topics

Elasticity and viscosity

Viscoelastic scales

Phase diagrams and viscoelasticity

Rheometry

Rheological behavior


Demonstrations of various types of fluid flow comes from the National Committee for Fluid Mechanics Films.

Bibliography

E.M. Purcell. "Life at Low Reynolds Number", American Journal of Physics vol 45, p. 3-11, 1977.

M.C. Potter, J.F. Foss, Fluid Mechanics, Great Lakes Press, 1982.

R.A.L. Jones, Soft Condensed Matter , Oxford University Press, Oxford (2002).

Extended Reading

  • Goodwin
    • Chapter 1 Introduction
      • "Firstly, we should be aware that intermolecular forces control the way our materials behave. This is where the chemical nature is controlling the physical response. Second, we should be aware of the importance of the timescale of our observations." These two ideas are linked through the "structure that is the consequence of the forces and timescale changes by microstructural motion resulting from thermal or mechanical energy." p. 1
  • Larson
    • Chapter 1. Introduction to complex fluids
    • Chapter 3. Polymers
    • Chapter 7. Particulate gels
  • Macoscko
    • Chapter 5. Shear rheometry: Drag flows
    • Chapter 7. Extentsional rheometry
    • Chapter 11. Rheology of polymeric liquids
  • Norde
    • Chapter 17. Rheology
      • Viscous materials deform (flow) at a constant rate so long as the force is imposed and the deformation remains after the force is released. The energy from the force is released as heat. Upon application of force, all of the bonds are instantaneously broken. p. 343,344
      • Elastic materials deform so long as the force is applied, but return to their original state when the force is released. The energy from the force is stored and then released to return the material to its original state. No bonds are broken and a force is required to maintain a constant deformation. p. 343,344
      • In viscoelastic materials, the bonds are gradually disrupted and the force required to maintain a constant deformation gradually decreases (usually exponentially) over time. p. 344
      • "The presence of electric charge along a polymer chain complicates the rheological behavior. In particular, the viscosity of a polyelectrolyte solution is very sensitive to the ionic strength. At high ionic strength electrostatic interactions between the charged groups are effectively screened so that the polyelectrolyte behaves as an uncharged polymer. On decreasing ionic strength, the polyelectrolyte molecules swell due to intramolecular electrostatic repulsion," and thus increases the viscosity. p 356

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