Dielectric relaxation measurements of Nylon-11 with substituted phenols p-Cresol, m-Cresol and o-Cresol mixture in different non-polar solvents CCl4, benzene and 1,4-dioxan for different concentrations over the frequency range of 10 MHz-20 GHz at 303 K have been carried out using Time Domain Reflectometry (TDR). Dielectric parameters such as static permittivity (ε0) and relaxation time (τ) were determined and discussed to yield information on the molecular structure and dynamics of the mixture. The dielectric constant and relaxation time were found to be high for Nylon-11 with p-Cresol in CCl4 compared to the other mixtures. © 2008 Elsevier B.V. All rights reserved.

Malathi M

Department of Physics

School of Advanced Sciences

Vellore Campus

Kumar P.M

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Journal of Molecular Liquids

A dielectric spectroscopic study has been carried out on binary mixtures of polar nitromethane (NM) with primary alcohols: ethanol (ETH), 1-propanol (1-PRO) and 1-butanol (1-BUT) at different temperatures. The complex dielectric spectra of pure and binary mixtures were described by Debye model. The dielectric constant (ε0), relaxation time (τ), and dielectric constant at an optical frequency (ε∞) of binary mixtures were determined at various temperatures. The computed excess dielectric parameters were used to interpret the intermolecular interaction between the unlike dipoles within the binary mixture system. From the experimental analysis, it is confirmed that, the mixture molecules form H-bond complex structure and dipoles are aligned in anti-parallel direction. Among all the binary systems, strong H-bond interaction can be seen in NM + 1-PRO mixture system. Rapid decrement of relaxation time for NM + 1-BUT binary system results higher amount of structural changes symmetry breaking effect. The formation of hydrogen bonding interaction between oxygen atom of nitro groups in NM and hydrogen atom of alcohols in binary mixture systems was confirmed by FTIR analysis.

Indian Journal of Physics

Study of the H-bond interaction on binary mixtures of nitromethane with primary alcohols at different temperatures using dielectric parameters

The dielectric complex spectra of 2-nitrotoluene with primary or secondary alcohol binary mixtures were studied over the frequency range of 10 MHz to 20 GHz for the whole solute mole fraction range at four different temperatures. An unusual suppression phenomenon was observed in the real and imaginary parts of the mixture complex spectrum, which are smaller than those for the pure alcohols, at low solute concentrations. The dielectric constant and dielectric relaxation time values were obtained by fitting the complex dielectric spectrum data to the single Debye model using a non-linear least squares method. The dielectric constant of mixtures decrease with the increasing mole fraction of 2NT in both the primary alcohols and secondary alcohols; the dielectric relaxation time decreases for all the five binary systems. Using the dielectric data, derived dielectric parameters, namely: the excess dielectric constant, excess inverse relaxation time, effective Kirkwood correlation factor, molar activation enthalpy and molar activation entropy, were calculated. The non-linear variation of permittivity (ɛ0) reveals the change in size and shape of hetero-molecular complex due to intermolecular H-bond interaction. The negative variation of the excess permittivity constant confirms that the dipoles form multimer structures with anti-parallel ordering of unlike dipoles. The molar activation enthalpy was found to be higher at 0.2 mol fraction of 2NT for primary alcohol binary system. To confirm the molecular function group interaction, a FT-IR spectroscopy study was carried out at 298 K. The FT-IR analysis confirmed the formation of hydrogen bonds between the hydrogen atom of hydroxyl groups of the alcohols and the oxygen atom of nitro groups of 2NT in the binary mixtures. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.

Journal of Solution Chemistry

Dielectric Relaxation and Thermodynamic Studies of Binary Mixtures of 2-Nitrotoluene with Primary and Secondary Alcohols at Different Temperatures

The microwave dielectric relaxation behavior of binary mixtures of nitrobenzene with primary alcohols namely ethanol, 1-propanol and 1-butanol has been studied at different temperatures using Time Domain Reflectometry method. The measured complex dielectric spectra of pure and mixture solutions have been fitted with Debye model using least square method. The obtained static dielectric and relaxation time constant values are plotted against mole fraction of solute. The important dielectric parameters such as excess dielectric constant, excess inverse relaxation time and effective Kirkwood correlation factors are computed and the same has been used to interpret the intermolecular interaction and dynamic change in the solution. Furthermore, the mixing effect of nitrobenzene in different chain length alcohols has been explored by concentration dependent excess dielectric constant values. The positive molar enthalpy values of mixtures indicate that the heat energy is absorbed owing to the process of dipole reorientation. Moreover, the heterogeneous interaction between solute and solvent molecular functional groups has been confirmed by equi-molar FT-IR spectra analysis. © 2016

Microwave dielectric relaxation spectroscopy studies on associative polar binary mixtures of nitrobenzene with primary alcohols

The complex dielectric spectra of nitrobenzene, 2-butanol and their binary mixtures were measured in the frequency range of 10 MHz-20 GHz at different temperatures using Time Domain Reflectometry. The static permittivities and relaxation times were extracted from the complex dielectric spectra of the pure compounds and binary mixtures by fitting to the Debye model using the least-squares fitting method. The derived static permittivity (ε 0) and dielectric relaxation time (τ 0) values were used to calculate various dielectric parameters including the excess dielectric constant, effective Kirkwood correlation factor, excess inverse relaxation time and thermodynamic parameters. Excess dielectric parameters were fitted with the Redlich-Kister type polynomial equation. The result from dielectric analyses confirms the formation of a heterogeneous complex structure by association of unlike molecules. This hetero-molecule interactions produce a electric field in the mixtures and, as a result, the effective dipoles rotate faster. Molecular rotation and dipole reorientation motions in these complex system are discussed in terms of the molar activation entropy and enthalpy. Additionally, the hydrogen bond interaction between solute and solvent were confirmed by FT-IR spectral analysis. © 2016 Springer Science+Business Media New York.

Thermodynamic and Molecular Dielectric Relaxation Studies of Polar–Polar Binary Mixtures Using Time Domain Reflectometry Technique

The hydrogen-bonded complexes formed by formamide and acetamide with phenols of varying pKa in 1,4-dioxan were studied. The following phenols (pKa in parentheses) were used: p-Cresol (10.17), p-chlorophenol (9.38), 2,4-dichlorophenol (7.85) and p-nitrophenol (7.15). The dipole moment of the complex was determined using the Huyskens method. Our results show that the lone pair electrons of the carbonyl group of the amides is the single acceptor site forming a linear hydrogen bond. The excess dipole moments of the complexes were obtained from bond angle data. Our results show that the proton acceptor abilities of the two amides are almost the same and the polarity of the complexes depends more on ΔpKa. Increasing the acidity of phenols, the dipolar increments also increase. The results are discussed in the light of polarization and tautomeric equilibrium. © 2003 Elsevier B.V. All rights reserved.

Dielectric studies of H-bonded complexes of formamide and acetamide with substituted phenols

The dielectric constants and dielectric losses of formamide, acetamide, N-methyl acetamide, acetanilide and N,N-dimethyl acetamide in dilute solutions of 1,4-dioxan/benzene have been measured at 308 K using 9.37 GHz, dielectric relaxation set up. The relaxation time for the over all rotation τ (1) and that for the group rotation τ(2) of (the molecules were determined using Higasi's method. The activation energies for the processes of dielectric relaxation and viscous flow were determined by using Eyring's rate theory. From relaxation time behaviour of amides in non-polar solvent, solute-solvent and solute-solute type of molecular association is proposed. © 2003 Published by Elsevier B.V.

Materials Science and Engineering: B

Dielectric relaxation studies of dilute solutions of amides

Polymer International

Dielectric relaxation behaviour of poly(cyclobutyl methacrylate)s

Dynamic mechanical and dielectric relaxation behaviour of poly(methacrylate)s containing saturated rings with seven and eight members in the side-chains

Journal	Data powered by TypesetJournal of Molecular Liquids
Publisher	Data powered by TypesetElsevier BV
ISSN	0167-7322
Open Access	0