A comparative dielectric relaxation study between hydrogen-and non-hydrogen-bonded liquids: Nitriles vs alcohols

Helambe, S. N.; Lokhande, M. P.; Kumbharkhane, A.C.; Mehrotra, S. C.

doi:10.1007/bf02848094

Cited by 19 publications

(6 citation statements)

References 11 publications

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“…6 The static permittivity data used here are the real part of the dielectric constant, which is reported at a wavelength of 30 000 cm by Garg et al 6 Dielectric relaxation times for a group of n-alkyl bromides over the temperature range 1-55 °C were obtained from the work of Hennelly et al, 7 while static dielectric constant data were taken from Landolt-Bornstein. 8 Dielectric relaxation times and static dielectric constants for a group of n-nitriles over the temperature range 0-45 °C were obtained from the work of Helambe et al 9 Static dielectric constants measured at 1 MHz and dielectric relaxation times for a group of n-acetates over the temperature range 15-50 °C were obtained from the work of Rajyam et al 10…”

Section: Reported Datamentioning

confidence: 99%

Application of the Compensated Arrhenius Formalism to Dielectric Relaxation

Petrowsky

Frech

2009

J. Phys. Chem. B

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The temperature dependence of the dielectric rate constant, defined as the reciprocal of the dielectric relaxation time, is examined for several groups of organic solvents. Early studies of linear alcohols using a simple Arrhenius equation found that the activation energy was dependent on the chain length of the alcohol. This paper re-examines the earlier data using a compensated Arrhenius formalism that assumes the presence of a temperature-dependent static dielectric constant in the exponential prefactor. Scaling temperature-dependent rate constants to isothermal rate constants so that the dielectric constant dependence is removed results in calculated energies of activation E(a) in which there is a small increase with chain length. These energies of activation are very similar to those calculated from ionic conductivity data using compensated Arrhenius formalism. This treatment is then extended to dielectic relaxation data for n-alkyl bromides, n-nitriles, and n-acetates. The exponential prefactor is determined by dividing the temperature-dependent rate constants by the Boltzmann term exp(-E(a)/RT). Plotting the prefactors versus the static dielectric constant places the data on a single master curve for each group of solvents.

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Section: Reported Datamentioning

confidence: 99%

Application of the Compensated Arrhenius Formalism to Dielectric Relaxation

Petrowsky

Frech

2009

J. Phys. Chem. B

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“…Interestingly, the various physical parameters determined for this binary system vary smoothly between its component values, indicating an isomorphic relationship between the phase-I of both the pure components. Evidence is presented here to show that binary system of CNCH + CHC (which is non-hydrogen bonded 96 ) with x m in the range 0.00 r x m r 0.4 could also be one such example which interestingly behaves like a single component orientationally disordered phase that demonstrates a glass like phenomenon. Another process of much smaller magnitude designated as a 0 -process was found above the glass transition temperature T g which kinetically freezes around 165-170 K and may be identified with (axial) chair-(equatorial) chair transformation as in the cyclohexyl derivatives.…”

Section: Discussionmentioning

confidence: 91%

Study of supercooled orientationally disordered binary solid solutions II: cyclohexyl derivatives, neopentanol and neopentylglycol

Singh

Murthy

Singh

2009

Phys. Chem. Chem. Phys.

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The main aim of the present investigation is to see how various relaxation processes including the chair-chair transformation (as found by earlier researchers at room temperature in mechanical relaxation spectroscopy) in cyclohexane derivatives evolve as the temperature is lowered. For this purpose, four remarkable (two-component) solid solutions that are orientationally disordered are investigated, where the first three systems are hydrogen (H-) bonded pairs, and the fourth is a non-H bonded pair. The former group is the two-component system of cyclohexanol (CHXOL) + 2,2-dimethyl-1-propanol or neopentanol (NPOL); cyclohexanol (CHXOL) + cycloheptanol (CHPOL) & neopentanol (NPOL) + neopentylglycol (NPGOL) systems, and the lone non H-bonded pair that has been studied is cyanocyclohexane (CNCH) and cyclohexylchloride (CHC). In all these cases, the liquid mixtures on cooling form orientationally disordered phases which are a solid solution of the corresponding pure phases. The feature is common to all the four systems studied here, but in CHXOL + CHPOL, the phase I of CHXOL beyond x(m) > or = 0.1 only forms a solid solution (designated as S(I')) with the phase I of CHPOL. In CNCH + CHC the solid phase is stable for the concentration range 0 < or = x(m) < or = 0.4 (without transition to any other phase). The above solid phase I (or I') has been investigated at low temperatures and for several concentrations, by means of dielectric spectroscopy and differential scanning calorimetry (DSC). Depending upon the concentration, this phase reveals a glass transition in the temperature range 116-150 K and associated with this is a pronounced relaxation process identifiable with the so called alpha-process. The dielectric spectra of this process is found to follow the Havriliak-Negami (HN) equation. In context of the binary system study here, the analysis of the various parameters obtained show an isomorphic relationship between the phases of the pure components through a continuous change of parameters. Another process of much smaller magnitude designated as the alpha'-process was also found in systems consisting of cyclohexyl derivatives above the glass transition temperature T(g) which kinetically freezes around 170 K. This process interestingly, is also non-Arrhenius in nature, becomes increasingly weaker with increase in the second component, and may be identified with (axial) chair-(equatorial) chair transformation. In addition in all these systems, a weak high-frequency process and a clear sub-T(g) process, are found which are designated as the beta- & gamma-processes respectively. The beta-process may be identified with Johari-Goldstein (JG) or beta(JG) process as it is found to follow the predictions of the coupling model proposed by Ngai. However, the identification of the gamma-process with internal degrees of freedom are fraught with some problems in the interpretation of the experimental data that are highlighted. The kinetic freezing of the various dielectric processes have been critically examined in relation to ...

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“…The dielectric relaxation study of solute-solvent mixture at microwave frequencies gives information about formation of monomers and multimers as well as interaction between the molecules of the mixture [1][2][3]. Acetonitrile (ACN) is nonassociative and 1,2 Dichloroethane (DE) is associative liquids, one with C≡N group and other with chlorine group.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Relaxation Study of Acetonitrile with 1,2-dichloroethane Using TDR

Pawar¹,

Patil²,

Mehrotra³

2011

2011 IEEE International Conference on Dielectric Liquids

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The dielectric relaxation study of acetonitrile with 1,2-dichloroethane mixture has been carried out at temperatures 15, 25, 35 and 45 o C. The dielectric relaxation study of solute-solvent mixture at microwave frequencies gives information about the formation of monomers and multimers as well as interaction between the molecules of the mixture. The dielectric parameters viz. static dielectric constant (ε 0 ) and relaxation time (τ) have been obtained by the least squares fit method. The static dielectric constant increases and relaxation time decreases with increase in concentration of acetonitrile in 1, 2-dichloroethane in the system. Excess properties and Kirkwood correlation factor of the mixtures have been determined. The static dielectric constants for the mixtures have been fitted with the modified Bruggeman model.

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A comparative dielectric relaxation study between hydrogen-and non-hydrogen-bonded liquids: Nitriles vs alcohols

Cited by 19 publications

References 11 publications

Application of the Compensated Arrhenius Formalism to Dielectric Relaxation

Application of the Compensated Arrhenius Formalism to Dielectric Relaxation

Study of supercooled orientationally disordered binary solid solutions II: cyclohexyl derivatives, neopentanol and neopentylglycol

Dielectric Relaxation Study of Acetonitrile with 1,2-dichloroethane Using TDR

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