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Authors
Affiliations
1 Department of Chemistry, Saurashtra University, Rajkot-360005, Gujarat, IN
Source
Journal of Pure and Applied Ultrasonics, Vol 26, No 2-3 (2004), Pagination: 49-57
Abstract
Ultrasonic velocity (2 MHz) and acoustical parameters of poly (R, R', 4, 4'-cyclohexyli-dene diphenylene toluene-2, 4-disulfonates) (PS-3: R=R'=Cl and PS-4: R=CH3 and R'=Cl) solutions investigated to understand the effect of methyl and chlorine substituents on molecular interactions. The linear increase of ultrasonic velocity (U), acoustical impedance (Z), Rao's molar sound function (R), Van der Waals constant (b) and internal pressure (π); and nonlinear increase of classical absorption coefficient (α/f2)Cl and viscous relaxation time(τ) with C and decrease with T; and linear decrease of isentropic compressibility (κS) relaxation strength (r), free length(Lf) and free volume (Vf) (nonlinear) with concentration (C) and increase with temperature(T) suggested the existence of powerful molecular interactions and hence solvophilic nature of the polymers, which is supported by positive values of solvation number (Sn). Structural modification (entanglement) is found above 2% concentration in 1,2- dichloroethane and THF systems. The linear increase of Sn with C and T indicated the presence of predominant polymer-solvent interactions over polymer-polymer interactions. The decrease of Sn with T is due to breaking of structure by predominant thermal energy over molecular interaction energy.
Keywords
Ultrasonic Velocity, Acoustical Parameters, Polymer-Solvent and Polymer-Polymer Interactions.
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