OA Journal Articles

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Browsing OA Journal Articles by Subject "Physics"

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    Determination of Wada Constant, Rao’s Constant, Compressibility and viscosity of a Cholesteric Liquid Crystal Solution at Various Temperatures
    (International Journal of Engineering Research & Technology, 2014) Kanwar, Anita; Mhatre, Pritee
    The ultrasonic waves having different frequencies propagate through the liquid crystal solution with different velocities at various temperatures. This fact helps in studying physical and chemical properties of Cholesteric liquid crystal (CLC) of different concentration at various temperatures. We in our laboratory have found out Acoustic Impedance, Rao’s constant, Adiabatic Compressibility, Wada constant, Van der Waals’ constant, Free Volume, Internal pressure and Classical Absorption Co-efficientof CLC solutionof different concentration. The measurements were made at various temperatures using Ultrasonic interferometer working at the frequencies 3MHz and 5MHz. The results so obtained are analyzed to see the effect temperature, concentration and transition of CLC into various mesophases. It is observed that when the miscibility is high and the solution is highly homogeneous the values of the parameters change drastically showing the change in the mesophases at phase transition temperatures.
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    Effect of Temperature and Concentration on the Physical Properties of Cholesteryl Pelargonate Near Transition Temperatures
    (Journal of Scientific Research, 2021) Gajghate, Vishakha; Kanwar, Anita
    Thermodynamic and acoustical study of cholesteric liquid crystal (CLC) was carried out near phase transition temperatures using an ultrasonic interferometer. The study of ultrasonic waves and related thermo-acoustical parameters provides information in understanding the nature of molecular interactions associated with liquid crystals. A statistical mechanical approach is used to calculate the viscosity of samples. The characteristic textures and phase transition temperatures are obtained with Polarizing Microscopy (POM). Fabry Perot scattering studies (FPSS) are used to ascertain the phase transition temperatures of CLC. The thermo-acoustical parameters have been calculated using experimental data with well-known formulae. The acoustical parameters show variation with temperature as well as with concentration of CLC. Anomalous behavior of these parameters is noticed at the clearing temperature of CLC. The variation of the parameters is explained in terms of solute-solvent molecular interactions in the solution. The molecular behavior, structural changes, and intermolecular interactions between CLC and solvent are discussed in detail.
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    Temperature and Concentration dependence of Refractive Index of Cholesteric Liquid Crystal Solution
    (Physical Chemistry: An Indian Journal, 2012) Kanwar, Anita; Yadav, Priya
    Average refractive indices of Cholesteric liquid crystal (Cholesteryl pelargonate: CP) dissolved in a soluble solvent were measured at various temperatures and concentrations. Multi-wavelength (visible range) refractometer made using hollow prism is used in the measurement. Due to variation in extra-ordinary and ordinary refractive index average refractive index changes with temperature for various concentrations of the solution. The changes in average refractive index were investigated for three wavelengths: 404 nm, 546 nm and 578 nm. Results so obtained are pre- sented in this paper and are in accordance with claim by Hecht in his book.