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KMID : 0369819950250030213
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Jorunal of Korean Pharmaceutical Sciences
1995 Volume.25 No. 3 p.213 ~ p.222
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Studies on the Flow Properties of Semi-Solid Dosage Forms (I): Steady Sheat Flow Behavior of Toothpates
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Abstract
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The steady shear flow properties of six kinds of commercial toothpastes were measured using a concentric cylinder type rheometer. In this paper, the shear rate and temperature dependencies oft heir flow behavior were investigated and the validity
of the
Casson and Herschel-Bulkley models was examined. Further, the flow properties over a wide temperature range were quantitatively evaluated by calculating the various material parameters. Main results obtained from this study can be summarized as
follows:
(1) Toothpastes are plastic fluids with a yield stress and their flow behavior shows shear-thinning characteristics. (2) With increasing temperature. The degree of shear-thinning becomes weaker and the Newtonian flow behavior occurs at a lower
shear
rate range. (3) The Herschel-Bulkley and model is more effective than the Casson model in predicting their flow behavior (4) As the temperature increases, the yield stress. plastic viscosity and consistency index become smaller, on the contrary,
the
flow behavior becomes larger.
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KEYWORD
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