Premium
Dielectric relaxation and thermodynamic properties of polyvinylpyrrolidone using time domain reflectometry
Author(s) -
Sarode Arvind V.,
Kumbharkhane Ashok C.
Publication year - 2012
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.3217
Subject(s) - dielectric , enthalpy , reflectometry , activation energy , materials science , dielectric loss , permittivity , thermodynamics , relaxation (psychology) , atmospheric temperature range , dipole , analytical chemistry (journal) , chemistry , time domain , organic chemistry , physics , psychology , social psychology , optoelectronics , computer science , computer vision
Temperature‐dependent values of dielectric permittivity ε′ and dielectric loss ε″ of polyvinylpyrrolidone (PVP, commercialized as PVP K‐60) solution of average molecular weight 160 000 g mol −1 were measured. The measurements were carried out in the frequency range 10 MHz to 20 GHz using time domain reflectometry at temperatures from 25 to 0 °C. The dielectric spectra can be described by the Davidson‐Cole model. Dielectric parameters such as the static dielectric constant ε 0 , the high frequency limiting dielectric constant ε ∞ , the relaxation time τ 0 and the distribution parameter β and thermodynamic parameters such as the free energy of activation Δ F τ , the enthalpy of activation Δ H τ and the entropy of activation Δ S τ were determined. The average free energy of activation was found to be in the range 12.55–14.65 KJ mol −1 and the enthalpy of activation was found to be 6.86 KJ mol −1 . Entropies of activation were found to be positive at all the measured temperature values and these large positive values of entropies reveal a less ordered structure of the PVP solution. The Kirkwood correlation factor g and the dipole moment µ were also determined for PVP solution. The results were compared with the results of the PVP‐water system studied previously. Copyright © 2011 Society of Chemical Industry