Ultrasonic Characterization of Aqueous Polyvinyl Pyrrolidone (PVP)

Aim: Various thermo acoustic parameters such as adiabatic compressibility (ba), relaxation time(t), acoustic impedance (z), classical absorption ( ), free length (Lf), isothermal compressibility (bi), volume expansivity (α) and Moelwyn-Hughes parameter (C1) of PVP solution were obtained from the measurement of ultrasonic velocity (u) , density(ρ) and viscosity(η).

Methodology: All these measurements were made by Pulse Echo technique at different concentration of the range 0.05 to 0.3wt. % and at 288K, 293K, 298K, 303K and 308K. The ultrasonic velocity (u) was observed to vary linearly with concentration of PVP solution.

Results: This indicates the single phase formation and the compatibility of aqueous PVP. The compatibility is due to the linear chain structure of the polymer. Adiabatic compressibility and free length decreases linearly with increase in concentration of aqueous PVP solution indicates that the strong interactions, association and non-dominance of PVP in water, because there is no abrupt change in the variation at any concentration. The increase in acoustic impedance (z) of aqueous PVP solution indicates that there is a strong molecular interaction between the polymer and the solvent molecules and the structural arrangement may be affected. This change in the structure of solvent or solution is a result of hydrogen bond formation and structure making property of PVP in solution.

Conclusion: Due to linear nature of ultrasonic parameters like ultrasonic velocity, adiabatic compressibility, etc. in PVP solution indicates that this PVP water soluble polymer can be used as tablet binder in pharmaceutical industries.