Studies on thermo-acoustic parameters in the dilute solutions of poly(ethyleneglycol)
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Studies on thermo-acoustic parameters in the dilute solutions of poly(ethyleneglycol) F. M. Sannaningannavar • B. S. Navati • N. H. Ayachit
Received: 14 June 2012 / Revised: 11 September 2012 / Accepted: 6 November 2012 / Published online: 24 November 2012 Ó Springer-Verlag Berlin Heidelberg 2012
Abstract Ultrasonic velocities and densities have been measured for the dilute solutions of poly(ethylene glycol) of average molecular mass 400 g mol-1 in benzene at different temperatures between 299 and 328 K. The experimental data have been used to compute the thermo-acoustical parameters namely isentropic compressibility (b), intermolecular free length (Lf), molar volume (Vm), Schoff’s available volume (Va(s)), acoustic impedance (Z), molar sound velocity (Ra), and molar compressibility (W). Variation of these parameters with temperature of the sample and mole fraction of the solute in the solution, keeping one of the either constant has been discussed to collect the informations on molecular structure and intermolecular interactions. Keywords Ultrasonic velocities Isentropic compressibility Intermolecular free length Specific acoustic impedance and thermo-acoustic parameters
Introduction The property of an ultrasonic wave to pass through the matter can be effectively used for many practical applications [1]. Physical, chemical, thermo-dynamical, and acoustical properties of pure polymer liquids and their behavior in dilute solutions with non-polar solvents are of great significance, as they are known to provide valuable information on the activities taking place at microlevel. Magnitude of ultrasonic velocity (u) is highly sensitive to the binding forces between atoms and molecules [2]. The nature and extent of molecular interactions among the components of the dilute F. M. Sannaningannavar B. S. Navati Department of Physics, Karnatak Science College, Dharwad, Karnataka, India N. H. Ayachit (&) Department of Physics, BVB College of Engineering & Technolgy, Hubli, Karnataka, India e-mail: [email protected]
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Polym. Bull. (2013) 70:603–618
solutions can certainly be explored adopting sensitive ultrasonic techniques and volumetric investigations [1]. The study of thermo-acoustical and thermo-dynamical parameters by these methods of dilute solutions with concentration variation at given temperature and with temperature variation at given concentration are known to reveal qualitative as well as quantitative information on molecular packing, molecular motion, structural organization and alteration, molecular association, extent of salvation, effect of solvent environment, formation and dissociation of hydrogen bonds, flexibility of polymer chains, polymer segment movements, stiffening and loosening of polymer chains, mass transfer and heat transfer. The studies on volumetric and ultrasonic properties of solutions and their dependence on composition and temperature are the requirements of the hour, due to their applications in chemical, industrial, and biologic processes. In dilute solutions, with
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