摘要:

The movement of water originated by the spreading of two surfactants was analyzed in glass beads as well as on soil systems, both of particles of nonuniform size

ISSN:0193-2691    

DOI:10.1080/01932690008913323

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The presence of vitamin K1in human body is important for preventing the hemorrhagic disease. Due to its very long side chain, vitamin K1is highly insoluble in water. We have successfully dissolve a substantial amount of vitamin K1in solutions of a commercial surfactant containing carboxymethyl ethoxylates (Hüls B433) and obtained low interfacial tension (IFT) and stable emulsion systems. This paper will present the details of these experiments. The solubilization of vitamin K1was estimated from UV absorption. The IFT values were measured by using a spinning drop apparatus and all particle sizes were determined by using laser light scattering. By using the Hüls B433 surfactant and an optimum amount of CaCl2, we can dissolve vitamin K1in water and obtain low IFT systems in the order of 10−2dyne/cm. The emulsions obtained in these systems are stable and contain droplet sizes below 65 nm. The dissolution of vitamin K1and the IFT behavior in these systems follow the rules for crude oil and prefer larger surfactant micelles.

ISSN:0193-2691    

DOI:10.1080/01932690008913324

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The association of ascorbic acid (H2A, AA) with α-tocopherol (α-T) enhances the antioxidant capability of the two vitamins in a microemulsion formed by water, pentanol and sodium dodecyl sulphate. The comparison of vitamin C oxidation kinetics in the presence and absence of α-T in the system shows that there are no tangible differences in the time of the ascorbic acid decomposition. The main effect is the enhancement of the H2A oxidation with increased pentanol concentration in the system. Ascorbic anion interacts with surfactant association structures, changing W/O microemulsion towards O/W system. The polar part of H2A is exposed to aqueous solution and subjected to oxidation.

ISSN:0193-2691    

DOI:10.1080/01932690008913325

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The changes of cloud points and surface tensions of a nonionic surfactant dodecyl polyoxycthylene(5) polyoxypropylene(4) ether (LS54) in aqueous solutions with added polyvinylpyrrolide (PVP-K90) were determined in order to evaluate polymer-surfactant interactions in the bulk solutions. A new model, corona-shaped intra-chain micelles, was applied lo these phenomena and the thermodynamic parameters of micellization were determined.

ISSN:0193-2691    

DOI:10.1080/01932690008913326

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The lamellar liquid crystalline phase in the system consisting of sodium oleate (NaOL), oleic acid (OLA), and water was determined. The interlayer spacing (d) of the lamellar liquid crystal was measured through small angle X-ray diffraction, which indicated that oleic acid molecules were solubilized between the end methyl groups at low concentrations, and then were located within the hydrocarbon chain layer with further increase of its concentration. Cross-linking agents were added to the system, which were found being located partly in between the end methyl groups and partly within the hydrocarbon chain layers. The liquid crystal phase of NaOL/OLA/H2O system with the cross-linking agent was polymerized at 60 °C, which turned out to be a mixture of liquid crystals and solids. Interlayer spacing decreased by about 10 Å, indicating a disruption of the ordered structure by the polymerization. The polymerization took place not only within the hydrocarbon layer, but also in between the layers separated by the end methyl groups. The resulting polymer lowered the surface tension of water to below 30 mN/m, with a critical micellization concentration of about O.25g/L.

ISSN:0193-2691    

DOI:10.1080/01932690008913327

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The structural change of the discontinuous cubic (I1) phase upon addition of oil (heptane, decane, and hexadecane) is investigated by small-angle x-ray scattering. In polyoxyethylene oleyl ether (C18.1EOn) systems having long polyoxyethylene chain (n=19.2, 30.1, and 50.8), theI1phase is formed in a wide concentration range. Only in C18.1EOnEO19.2EOnsystems, the structure of the I1phase changes from body-centered to face centered cubic lattice upon addition of oil. According to the analysis of the change in effective cross-sectional area, the solubilization of hexadecane increases the repulsion between polyoxyethylene chains, while solubilization of heptane makes it decrease. The solubilization of decane keeps the repulsion constant. Since the repulsion hampers the curvature change due to the solubilization, the solubilization capacity is in the order, heptane>decane>hexadecane. The oil penetration and nonpenetration into the palisade layer are also discussed in term of the change in the effective volume of the lipophilic part in the surfactant molecule.

ISSN:0193-2691    

DOI:10.1080/01932690008913328

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor