Nihon Reoroji Gakkaishi
Online ISSN : 2186-4586
Print ISSN : 0387-1533
ISSN-L : 0387-1533
Viscoelastic Properties of Fatty Acid Soap/Water Colloidal Systems
Toshiki MoriTakayoshi Matsumoto
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1999 Volume 27 Issue 3 Pages 183-187

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Abstract

Rheological properties and structure of the gel phase formed in potassium palmitate ( potassium n-hexadecanoate )/water colloidal systems have been investigated using dynamic viscoelastic measurements and small angle X-ray scattering(SAXS). This colloidal systems formed lamellar structure in the gel phase which are stable at 25°C. Lamellar repeat distance, which is the thickness of the surfactant layer puls water layer, is linearly related to φWS, where φW and φS are the weight fraction of water and surfactant, respectively. From this analysis, the thickness and the density of the surfactant layer and the surface area per surfactant molecule are estimated as 2.21nm, 1.11g/cm3, and 0.399nm2, respectively. The values of storage modulus G' and loss modulus G” of the colloidal systems are almost equal over a wide range of frequency and they increase with increasing angular frequency ω in proportion to ω0.4. These viscoelastic properties of the gel phase differ from that of the lamellar liquid crystalline phase formed in the surfactant/water colloidal systems, although both phases have lamellar structure.

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© 1999 The Society of Rheology, Japan
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