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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 7, Number 4
April 20, 1986 

A New Flow Equation for Thixotropic Systems
Dae-Won Sohn, Eung-Ryul Kim, Sang-Joon Hahn, Taikyue Ree*
Thixotropy is a time-dependent shear-thinning phenomenon. We derived a new thixotropic formula which is based on the generalized viscosity formula of Ree and Eyring, f = Σ (Xi/αi)sinh-1 (βi·s) (Refer to the text concerning the notation.) The following is postulated: (1) thixotropy occurs when small flow units attached to a large flow unit separate from the latter under stress (2) elastic energy(ω) is stored on the large flow unit during the flow process, and (3) the stored energy contributes to decrease the activation energy for flow. A new thixotropic formula was derived by using these postulations, f = (X0β0/α0)s + (X1β1/α1)s + X2/α2)sinh-1[(β 0)2 exp (- C2s2/RT)·s] f is the shear stress, and s is the rate of shear. In case of concentrated solutions where the Newtonian flow units have little contribution to the viscosity of the system, the above equation becomes, f = (X2/α 2)sinh-1 [(β0)2 exp (- C2s2/RT)·]. In order to confirm these formulas, we applied to TiO2(anatase and rutile)-water, printing ink and mayonnaise systems. Good agreements between the experiment and theory were observed.
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