ABSTRACT
Lamellar phase samples of AOT/isooctane/water ternary system were prepared. The microstructure of the lamellar phase containing nanosized silica particles was examined by optical polarized microscope [OPM] and Small Angle X-ray scattering [SAXS]. Both were used to investigate the phases changing for different silica particle concentrations. The interaction between dopled particle and bilayer of lamellar phase were analyzed and the change of silica concentration shows the defection of the bilayer structure of lamellar phase. The effect of silica concentration was profound in the images of lamellar phase and the phase changed from birefringent to isotropic with increases of concentration
ABSTRACT
Fractional calculus has become an important tool in the analysis of slow relaxation phenomena, such as stress-strain relationships in polymeric materials. The interaction of trilblock copolymer [Pluronics f68] with cetyltrimethylammonium bromide [CTAB]-sodium nitrate [NaNO3] wormlike micellar system in low and high salt concentration is investigated by rheological measurements. Undoped wormlike micellar solution is a viscoelastic fluid which exhibits Maxwellian behavior. Since the rheology of solutions still Maxwellian, a fractional Maxell model is applied to describe any changes. A fractional derivatives of order q and The Maxwell model consists of a spring and dashpot in series. The fractional Maxwell model relating stress to strain is used to fit several experimental results on wormlike micelles in the presence of copolymer. The comparisons between the experimental results and the theoretical predictions are found to be satisfactory
Subject(s)
Micelles , Recombinant Proteins , RheologyABSTRACT
Mesoporous silica has been synthesized by gamma-irradiation using a non-ionic surfactant as template in the cubic and hexagonal lyotropic phases. The mesopores obtained in the two phases have different diameters, cubic phase silica being with the smaller pore size of the order of 3-4 nm whereas the hexagonal phase silica is giving large mesopores of value around 15 nm. The wall size differ in the two templated phases as well, cubic phase is with a small thickness of the order of 5.0 nm while the hexagonal silica exhibits a wall thickness of 15 nm under transmission electron microscopy [TEM] approximately. Both these cubic and hexagonal phases were further characterized by small angle X-ray scattering [SAXS], polarizing microscopy and rheometry. Radiation dose and templated phase are both playing effective role in the synthesis of mesoporous silica
Subject(s)
Polyethylene Glycols , Ethers , CrystallizationABSTRACT
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
Subject(s)
Liquid Crystals , Ultrasonics , Oils/chemistry , Surface-Active AgentsABSTRACT
Fractional calculus has become an important tool in the analysis of slow relaxation phenomena, such as stress-strain relationships in polymeric materials. The Zener model is an extension of the Maxwell model, which consists of a spring and dashpot in series, with an additional spring in parallel. A fractional rheological description is obtained by replacing the first order time-derivatives in the Maxwell-Zener equation with fractional derivatives of order q and micro. The fractional Zener model relating stress to strain is used to fit several experimental results on polysaccharide. The comparisons between the experimental results and the theoretical predictions are found to be satisfactory
ABSTRACT
The phase behaviours of three types of amino-acid based surfactants were explored. They are Sodium Cocoyl Glutamate [commercially known as Amisoft CS-11], Sodium Lauroyl Glutamate [commercially known as Amisoft LS-11] and Sodium Cocoyl Glycinate [commercially known as Amilite GCS-11]. The optical polarized microscope was used to observe the liquid crystalline phases and to capture images. The existence of liquid crystalline phases was further investigated by small angle X-ray scattering. The phase diagrams were investigated as a function of surfactant concentration and as a function of temperature as well. The rheological behaviours of liquid crystalline phase were also investigated. All surfactants were found to form two-phase region, micellar region at low concentration while liquid crystalline phases were found to form at high concentration