Temperature dependent Broadband dielectric relaxation study of Aqueous Polyvinylpyrrolidone (PVP K-15, K-30 & K-90) using a TDR

ABSTRACT

Temperature-dependent dielectric relaxation studies of different viscosity grade Polyvinylpyrrolidones (PVP), PVP K-15, PVP K-30 and PVP K-90 having molecular weight 10,000 gmol⁻¹, 40,000 gmol⁻¹ and 360,000 gmol⁻¹ respectively has been done in the frequency region 10 MHz to 50 GHz using Time domain reflectometry (TDR) technique. The frequency-dependent complex dielectric permittivity spectra have been explored by the Havriliak-Negami expression and is explained by the single relaxation model. The PVP molar concentration comprises the concentration domain of 0.0017 ≤ c/M ≤ 0.0176 for PVP-water system. The values of static dielectric constant (ε₀), relaxation time (τ) and the empirical parameter (β) have been determined using non-linear least squares fit method along with the thermodynamic properties (activation enthalpy, entropy and free energy) of aqueous solutions of polymers.

KEYWORDS:

• Time domain reflectometry (TDR)
• complex permittivity
• dielectric relaxation
• polyvinylpyrrolidone
• thermodynamic properties

Acknowledgements

The financial support from the Department of Science and Technology, New Delhi is gratefully acknowledged (Project no. DST PROJECTSB/S2/LOP-032/2013).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Department of Science and Technology, New Delhi [DST PROJECT SB/S2/LOP-032/2013].