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KMID : 0370219970410010038
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Yakhak Hoeji
1997 Volume.41 No. 1 p.38 ~ p.47
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Studies on the Flow Properties of Semi-Solid Dosage Forms (II) : Temperature-Dependent Flow Behavior of Vaseline
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김정화/Kim JH
송기원/장갑식/이장우/이치호/Song KW/Chang GS/Lee JO/Lee CH
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Abstract
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Using a concentric cylinder type, rheometer. the steady shear flow properties of vaseline were measured over the temperature range of 20~70oC. In this paper, the shear rate and temperature dependencies of its flow behavior were investigated and the validity of some flow models was examined. In addition, the flow characteristics over a wide temperature range were quantitatively evaluated by calculating the various material parameters. Main findings obtained from this study can be summarized as follows: (1) At relatively lower temperature range, vaseline is a plastic fluid with a yield stress and its flow behavior shows shear-thinning characteristics. (2) As the temperature increases, the value of a yield stress and the degree of shear-thinning become smaller, consequently, the Newtonian flow behavior occurs at a lower shear rate range. (3) At temperature range lower than 45oC, the flow behavior shows much stronger temperature dependence, and a larger activation energy is needed for flow. (4) The Herschel-Bulkley model is the most effective one g3 to predict the flow behavior of vaseline having a yield stress. The validity of the Bingham and Casson models becomes more available with increasing temperature. The flow behavior of vaseline at temperature range higher than 45oC can be perfectly described by the Newton model.
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