Effect of oil types and concentration on ultrasonic measurements of alkyl polyglucosides liquid crystal phases

ABSTRACT

Phase diagrams for the ternary systems of Glucopone, Water and several hydrocarbons are reported. Four different types of hydrocarbon are used namely; heptane, octane, dodecane and tetradecane. Small angle X-ray scattering [SAXS] and polarizing microscope are used for phase identification and structure characterization. The ternary systems are shown to form different liquid crystalline phases with the Increase of concentration in the following order - cubic, hexagonal, and lamellar. An optical isotropic gel phase with strong elastic properties is found in these systems and Identified as cubic phase. The cubic phase is optically isotropic, transparent and highly viscous phase with three-dimensional structure. The cubic samples showed several diffraction peaks and can be assigned to the la3d space group. The rheological study on the cubic phase is performed. All cubic samples behave as solid-like material with storage modulus G 0.7x10[6] Pa typical of cubic lyotropic materials. The effect of oil concentration in the ultrasonic measurements for the three different liquid crystalline phases is studied. The effect of different types of oil on the ultrasonic measurements is also investigated. The ultrasonic measurements showed that the ultrasonic velocity of the cubic samples Increased as the oil concentrations increased. The ultrasonic measurements showed that the ultrasonic velocities of the lamellar phases decreased with increase in the chain lengths of the hydrocarbon, while the ultrasonic velocities were almost similar for hexagonal phases