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Abstract

Suspensions show thixotropic behavior when the suspended phase is capable of forming a structure and the steady state degree of aggregation is a function of the steady state rate of shear. Experimental investigations of the steady state flow behavior and comparisons with the predictions of different theories have been reported by numerous authors. Systematic investigations of the time-dependent behavior are, however, much rarer. There are essentially three types of experiments which have been reported:
  1. a)

    After vigorous agitation (which completely destroys the structure) the suspension is allowed to rest and the degree of recovery (of structure) is tested after various time intervals.

     
  2. b)

    The shear stress τ(t) is measured as a function of a variable shear rate δ̇(t). Usually the shear rate is increased linearly with time up to a maximum and then decreased linearly to zero. The resulting τ VS. δ̇ relation is called “hysteresis loop”.

     
  3. c)

    The shear rate is held constant at δ̇ i until the shear stress reaches a steady state value. Then the shear rate is abruptly changed to a new value δ̇ f and the τ(δ̇ i , δ̇ f , t) relation determined. This is repeated for different combinations of δ̇ i and δ̇ f .

     

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Copyright information

© Springer-Verlag Berlin Heidelberg 1975

Authors and Affiliations

  • H. A. Mercer
    • 1
  • H. D. Weymann
    • 1
  1. 1.Department of Mechanical and Aerospace SciencesUniversity of RochesterRochesterUSA

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