Browsing by Author "Wheeler, Barbara A."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Phase Structure and Rheological Properties of a Mixed Zwitterionic/Anionic Surfactant System
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Saul, Dorothy; Tiddy, Gordon J. T.; Wheeler, Barbara A.; Wheeler, Phillip A.; Willis, Edwin
    The phase diagram of the mixed zwitterionic/anionic surfactant system hexadecyldimethyl- ammoniopropancsulphonate/sodium dodecyl sulphate/water has been determined in the aqueous region (>90.0 % water) by optical microscopy and low angle X-ray scattering; the phases observed were an isotropic surfactant solution and a hexagonal liquid crystalline phase. Some aqueous solutions were found to be viscoelastic and the composition boundaries of solutions with these properties were parallel to the phase boundaries. N.m.r. was used additionally to study the structure of the viscoelastic solutions and the results are interpreted using a model which involves the existence of both normal spherical micelles and cylindrical micelles in equilibrium.
  • No Thumbnail Available
    Item
    Phase Structure, Nuclear Magnetic Resonance and Rheological Properties of Viscoelastic Sodium Dodecyl Sulphate and Trimethylammonium Bromide Mixtures
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (1-6), 1974) Barker, Christopher A.; Saul, Dorothy; Tiddy, Gordon J. T.; Wheeler, Barbara A.; Willis, Edwin
    The phase diagram of octyltrimethylammonium bromide and sodium dodecyl sulphate (SDS) in water (>90 %) is reported at 298 K; the phase regions observed are liquid, two liquid, and liquid plus liquid crystal. Liquids with viscoelastic properties occur close to the SDS rich liquid boundary, and a correlation is observed between the surfactant n.m.r. linewidths and the rheological properties of these liquids. The most likely explanation of these effects is one involving the occurrence of both cylindrical and spherical micelles, but the possibility that the viscoelasticity is due to the presence of a microemulsion can not be excluded.