Seung-gak Yang , Won-jae Park , Ok-sub Lee , Hyuck-chel Kwon

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Abstract

The effect of liquid crystalline phase formation on preservation in ternary and O/W emulsion systems was investigated. Antimicrobial activity of methyl paraben in tested systems was more enhanced with the increasing concentration of fatty alcohols such as myristyl, cetyl, stearyl and cetostearyl alcohol except lauryl alcohol. With the increasing addition of such fatty alcohols, the increasing quantity of free methyl paraben in tested systems was determined by equilibrium dialysis method. The liquid crystal formed in presence of fatty alcohols was observed by a microscope under polarized light. However, liquid crystal could not be observed only in lauryl alcohol. From these results, we could conclude that the formation of liquid crystalline phase affects decrease of the micelle quantity and suppresses inactivation of methyl paraben.

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심규식 Kyoo Shik Shim , 이태규 Taikyue Ree

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Abstract

The interfacial properties of ferrosoferric oxide suspended in aqueous KNO₃ solution are investigated by studying the zeta potentials and surface charge densities at 25°C. The zeta potentials are obtained by measuring the electrophoretic mobility and the surface charge densities by potentiometric titrations in the aqueous KNO₃ solutions of different concentrations from 10^-3 to 10^-1M. The data are interpreted by the surface dissociation and complexation model of Davis, et als. and the modified model.

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五聖根 , 金鍾得

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Abstract

The microstructural transitions of aqueous micellar solutions of cetyltrime-thylammonium bromide and sodiumdodecyl sulfate by adding 1-hexanol were investigated, measuring the concentrations of equilibrated phases and the electrical conductivities at the low concentrations of surfactants, where the solobilities of 1-hexanol varied significantly, at 30℃ and 45°C. Ternary phase diagrams of multiphase regions, constructed by liquid chromatography analysis and by counting the number of phase of samples, consisted of one three-phase region and three two-phase regions. One of the two-phase regions was found to equilibrate an aqueous micellar solution and a liquid crystal, and had a critical point between them. Near this region, the solubility curve varied abruptly, and the isotropic solution turned birefrigent. The conductivities of the single phase regions above the critical point increased up to a certain point as 1-hexanol added, and then decreased, representing the microstructural transition at the supercritical region. Further, the solubility of 1-hexanol in aqueous micellar solution was found to increase as temperature and the number of hydrophilelipophile balance of surfactants increase.

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金昌奎

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Abstract

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