Ch. Srinivasu

Synthesis, characterisation and phase transition studies in N-(-4-ethyloxybenzylydene)-4’-alkoxyanilines

ABSTRACT Synthesis and characterisation are carried out in N-(-4-ethyloxybenzylidene)-4ʹ-alkoxyanilines, 2O.Om liquid crystalline (LC) compounds with m = 3, 4 and 6–10. All the compounds exhibit monovariant nematic phase except with m = 10; the LC material shows bivariant nematic-smectic-C in addition to the nematic phase. Further, the variation in density with temperature in all these seven compounds is studied. The density and thermal expansion coefficient results reveal that the phase transitions, namely isotropic to nematic and nematic to SmC, present in these compounds show first-order nature as expected and that all the parameters show characteristic change in the vicinity of the phase transformation. The results are discussed in the light of the data available on other nO.Om compounds. GRAPHICAL ABSTRACT

Excess Transport Properties of Binary Mixtures of Quinoline with Xylenes at Different Temperatures

The ultrasonic velocity and density of binary liquid mixtures of quinoline with o-xylene, m-xylene, and p-xylene have been measured over the entire range of composition at = 303.15, 308.15, 313.15, and 318.15 K. Using these data, various parameters like adiabatic compressibility (β), intermolecular free length (), and acoustic impedance () and some excess parameters like excess adiabatic compressibility (), excess intermolecular free length (), excess acoustic impedance (), and excess ultrasonic velocity () have been calculated for all the three mixtures. The calculated deviations and excess functions have been fitted to Redlich-Kister polynomial equation. The observed deviations have been explained on the basis of the intermolecular interactions present in these mixtures.

EXCESS ACOUSTICAL STUDIES IN LIQUID MIXTURES OF ANILINE WITH O-XYLENE AT DIFFERENT TEMPERATURES T= (303.15KK, 308.15K, 313.15K and 318.15) K

Excess acoustical parameters such as excess intermolecular free length (Lf), excess adiabatic compressibility (βE), excess acoustic impedance (ZE) and excess ultrasonic velocity (UE) have been computed from experimentally determined values of densities(ρ), ultrasonic velocities(u) and viscosities(η) in binary liquid mixtures containing aniline with o-xylene at temperatures T=(303.15,308.15,313.15 and 318.15)K. These results are fitted to the Redlich-Kister polynomial equation. These results have been explained on the basis of intermolecular interactions in liquid mixtures.

Thermodynamic parameters studies in N-(p-n-ethyloxybe-nzylidene)-p-n-alkoxy anilines

ABSTRACT From the computed thermal expansion coefficient from density variation with temperature, on N-(p-n-ethyloxybenzylidene)-p-n-alkoxy anilines, 2O.Om liquid crystalline (LC) compounds with m = 3–4 and 6–10, different thermodynamic parameters such as Sharma parameter (So), Huggins parameter (F), reduced volume (∼V), reduced compressibility (∼VC1), etc., are studied using the volume expansion coefficient (α), which is estimated from density in isotropic and liquid crystalline phases. The parameters like intermolecular free length (Lf), molecular radius (Mr), and Beyers nonlinearity parameter (B/A) are also computed from density data for the above compounds. Except with m = 10, the rest of the compounds exhibit nematic phase where as with m = 10, the LC material shows smectic-C in addition to the nematic phase. The results are discussed in the light of these parameters variation with temperature in a particular phase in a LC molecule and with the chain length, m. The thermodynamic parameter So exhibits a constant characteristic value in all the compounds like other reported liquid crystalline compounds, liquids, and polymers. Further, the molecular radius, Mr, and molecular free length, Lf, are estimated and the results are compared with the literature data available.

Experimental and Theoretical Evaluation of Ultrasonic Velocities of Binary Liquid Mixtures of Anisaldehyde and Toluene at Different Temperatures

Theoretical velocities of binary liquid mixtures of anisaldehyde with toluene at 303.15, 308.15, 313.15 and 318.15 K have been evaluated by using theoretical models of liquid mixtures such as Nomoto, Van Dael-Vangeel, Schaff’s collision factor theory and Junjie’s relations. Density and ultrasonic velocity of these mixtures have also been measured as a function of concentration and temperature and the experimental values are compared with the theoretical values. A good agreement has been found between experimental and Nomoto’s theoretical ultrasonic velocities. The results are explained in terms of intermolecular interactions occurring in these binary liquid mixtures.