Excess Permittivity Research Articles

Prediction of Dielectric Constants of (Cyclic Ketone- 1,4-Butanediol) Binary Systems

In order to predict the permittivity and excess permittivity data of binary systems containing cyclic ketones (cyclohexanone and cyclopentanone) and 1,4-butanediols, various mixing rules were used [1,2]. The permittivity increment, , was also evaluated in this research using the predicted data. x1 and x2 are the mole fractions of the components 1 and 2, and are the permittivities of the pure components. As shown in Fig. 1, the experimental permittivity values for three systems containing 1,4-butanediol (1,4BD) and two cyclic ketones were estimated by several mixing rules. Typically, for cyclohexanone and 1,4-butanediol mixtures, the predicted excess permittivity data were compared and shown in Fig. 2. As it can be seen from Table 1, the Lichteneker-Rother model shows the lower root mean square deviation (rmsd) value, which indicates that the Lichteneker-Rother model presents the best result between the predictive models.

Dielectric dispersion study of binary mixtures of methyl ethers with water at 298.15 K using frequency domain technique

A precision LCR meter along with a liquid dielectric cell have been used to measure the capacitance and resistance of the binary mixtures of methyl ethers with water at 298.15 K in the frequency range of 20 Hz to 2 MHz. The measured values are used to compute the complex dielectric permittivity ε*(ω) . The parameters like complex electrical modulus M*(ω) , complex electrical conductivity σ*(ω) and loss tangent (tan δ ) are obtained from the complex dielectric permittivity values of the samples. The values of excess dielectric permittivity of the samples are calculated using the respective static dielectric permittivity values. The refractive indices of all the samples were measured using Abbe’s refractometer at 298.15 K. All these parameters are used to gain insight into the concentration dependent variation in dielectric and electrical properties of the binary mixtures. A dominance of electrode polarization effect in the lower frequency region is observed for all the samples studied here.

Dielectric relaxation study of aqueous ethylene glycol mono-methyl ether (EGME) with water using time domain reflectometry technique in the frequency range 10MHz to 50GHz

The Complex permittivity spectra of glycol ether (GE) compounds such as ethylene glycol mono-methyl ether (EGME) with water mixture over entire concentration range and in temperature range of 10–25∘C have been determined using Time Domain Reflectometry (TDR) technique in the frequency range 10[Formula: see text]MHz to 50[Formula: see text]GHz. The complex permittivity spectra for EGME-water were fitted in the Cole–Davidson model. The Static dielectric constant ([Formula: see text], Relaxation time ([Formula: see text], effective Kirkwood correlation factor ([Formula: see text], excess permittivity ([Formula: see text], thermodynamic parameters (activation enthalpy and activation entropy) and Bruggeman factor ([Formula: see text] have been calculated by the nonlinear least square fit method. The intermolecular interactions between EGME-water binary mixtures suggest the nonlinear behavior of dielectric parameters. The contribution of hydrogen bonding interactions among the solute–solvent mixtures is confirmed by Excess properties and Bruggeman factor.

Dielectric relaxation and thermodynamic study of Dimethylformamide/1,4-Butanediol binary mixtures in the temperature range 298K–323K

In the present paper, the permittivity of Dimethylformamide (DMF) with 1,4-Butanediol (BD) binary mixtures are determined at the temperature range of 298 K–323 K in the microwave frequency. Dipole moment (μ), excess molar volume (VmE), partial molar volume (Vm,i), excess permittivity (εE), excess refractive index (nDE), excess inverse relaxation time (1/τ)ε, thermal expansion coefficient (αP), excess Helmholtz energy (ΔFE) are determined at different temperatures. Redlich-Kister polynomial equation is used to fit the excess parameters. Havriliak-Negami equation is used to analyse the relaxation time of the binary mixtures throughout the measured temperature range. The heteromolecular interaction between DMF and 1,4-Butanediol binary mixtures are interpreted in terms of Kirkwood correlation (geff) factor. The stability of the system is analysed from the activation energy (ΔG*), enthalpy (ΔH*) and entropy (ΔS*) parameters. The various mixing rules were applied in order to estimate the permittivity and refractive indices of the binary system at different temperatures.

Dielectric relaxation behaviour of ethyl acetate-xylene mixtures using time domain reflectometry

ABSTRACT Complex permittivity spectra were measured for the binary mixtures of Ethyl Acetate (EA) with Xylene using Time Domain Dielectric Spectroscopy (TDDS) for 11 concentrations at different temperatures in the frequency range from 10 MHz to 30 GHz. The values of static dielectric permittivity and relaxation time have been obtained by fitting complex permittivity spectra using least square fit method in Debye model. The observation of excess permittivity, excess relaxation time and Kirkwood correlation factor has been undertaken to study the behaviour of molecular structure in EA and Xylene using dielectric relaxation parameters.

Frequency and temperature dependent dielectric studies of propylene glycol-sulfolane binary mixtures in the microwave frequency region.

The dielectric permittivity of propylene glycol/sulfolane binary mixtures have been determined at various temperatures in the frequency range of 0.02 ˂ν/GHz˂ 20 using open-ended coaxial probe method. The permitivity spectra of propylene glycol/sulfolane mixtures with an asymmetric shape is observed. The experimental dielectric permittivity, relaxation time values are used to obtain remaining excessive parameters such as excess permittivity (εE), deviation in refractive index (ΔnD) excess inverse relaxation time (1/τ)ε, Kirkwood effective correlation factor (geff) and active thermodynamic parameters. Redlich-Kister polynomial equation is used to fit the excessive dielectric parameters. The molecular interaction between propylene glycol and sulfolane binary mixtures is interpreted in terms of short and long-range interactions among the dipoles. The experimental dipole moment values are compared with the theoretical dipole moment values from DFT/B3LYP, MP2 methods. Natural bond orbital (NBO) analysis is performed on the optimized geometrical structure of the above system to understand molecular interaction between the binary mixtures in terms of hydrogen bonding. The chemical stability of the system is studied from the HOMO-LUMO calculations. The energy of H- bond interaction between propylene glycol and sulfolane binary mixture is calculated from the single point energy calculations, and the results are correlated.

Environmental effect of lubricity additives through dielectric molecular parameters

Lubricant additives are chemicals, nearly always-organic or organometallic, that are added to oils in quantities of a few weight percent to improve the lubricating capacity and durability of the oil. Specific purposes of lubricant additives are improving the wear and friction characteristics by provision for adsorption and extreme pressure lubrication, improving the oxidation resistance, control of corrosion, control of contamination by reaction products, wear a and other debris, reducing excessive decrease of lubricant viscosity at high temperatures, enhancing lubricant characteristics by reducing the pour point and inhibiting the generation of foam. These properties depend upon the molecular interactions between the chemical additives. So that, this study target on investigating the molecular interactions through the dielectric parameters such as Kirkwood correlation factor, Excess permittivity, Bruggemann factor and Dipolar excess free energy in the lubricative binary mixtures,1) caprylic acid + 2-ethyl-1-hexanol and 2) valeric acid + 2-ethyl-1-hexanol. The above dielectric parameters have been calculated from the experimentally measured values of capacitance and refractive index of mixtures, at temperatures 303 K, 313 K and 323 K. In the above studied systems, existence of short and long range, homo and hetero interactions are identified. These interactions are found to be concentration and temperature dependent. The hetero interaction results in the formation linear as well as closed multimers in the mixture. Due to the existing interactions, structural changes are found to take place.

Investigation of temperature dependent dielectric relaxation studies of 1,4-Butanediol/DMSO binary mixtures at the microwave frequency

In the present manuscript, we are reporting the complex dielectric permittivity of 1,4-Butanediol/Dimethylsulfoxide binary mixtures for entire concentrations in the temperature range of 298.15 K–323.15 K. The complex dielectric permittivity is measured in the frequency range of 20 MHz–20 GHz. The dielectric relaxation time (τ) of the binary mixtures are analyzed by using the Havriliak-Negami equation. Redlich-Kister polynomial equation is used to fit the excess molar volume (VmE), excess permittivity (εE), excess refractive index (nDE), excess inverse relaxation time (1/τ)E. The molecular association and structural packing in the liquid mixture are analyzed by using thermal expansion coefficient (αP) parameter. The ordering nature of the molecular dipoles is discussed by evaluating the Kirkwood correlation factor(geff) and stability of the system by thermodynamic quantities. The experimental dipole moments of the pure and equimolar binary system are determined by using Higasi's method and compared with the theoretical dipole moment values obtained from DFT/B3LYP methods. Confirmation of hydrogen bond between 1,4-butanediol and DMSO is supported with the FT-IR and UV-Vis spectroscopy methods. The experimental dielectric and spectroscopic studies confirm the existence of hydrogen bond between the liquid mixtures.

Molecular Interaction Studies of Bromobenzene with Methoxyethanol and Ethoxyethanol

FTIR and Dielectric relaxation studies on bromobenzene with methoxyethanol and ethoxyethanol binary mixtures have been carried out at eleven concentrations at 303 K. Complex dielectric spectra were obtained in the frequency range of 10 MHz to 20 GHz using TDR. The least squares fit method has been used to obtain the static dielectric constant (ε0) and relaxation time (τ). By using these dielectric parameters, the excess permittivity (εE), excess inverse relaxation time (1/τ)E, Kirkwood correlation factor (geff) and corrective Kirkwood correlation factor (gf) are also obtained for investigating the intermolecular interaction. The dielectric parameters show systematic change with concentration and alkyl chain length of alcohols.

Dielectric Relaxation in Water-Ethanolamine Mixtures as a Function of Composition and Temperature

Dielectric relaxation measurements on water–ethanolamine solvent mixtures have been carried out across the entire concentration range using Time Domain Reflectometry technique at 288 K, 298 K, 308 K, and 318 K over the frequency range from 10 MHz to 20 GHz. The mixtures exhibit a principle dispersion of the Davidson-Cole relaxation type at microwave frequencies. Bilinear calibration method is used to obtain complex permittivity ε*(ω) from complex reflection coefficient ρ*(ω) over the frequency range 10 MHz to 10 GHz. The excess permittivity (εE), excess inverse relaxation time (1/τ)E, Kirkwood correlation factor (geff) and thermodynamic parameters are also calculated to study the Solute-Solvent interaction.

Dielectric Relaxation and FTIR Studies on Molecular Interaction between Ethylene Glycol Monobutyl Ether with Bromobenzene and Chlorobenzene

Complex dielectric spectra over the frequency range of 10 MHz–20 GHz and FTIR spectra in the region of 4000 cm−1–500 cm−1 of binary mixture of ethylene glycol monobutyl ether with chlorobenzene and bromobenzene were obtained over entire concentration range at 303 K. The static dielectric constant (ε0) and relaxation time (τ) have been obtained. Using these values the excess permittivity εΕ, excess inverse relaxation time (1/τ )E, Kirkwood correlation factor (geff), and corrective Kirkwood correlation factor (gf) were determined. On the basis of these parameters, intermolecular interaction and dynamics of molecules are predicated and conformational of the hydrogen bond is supported by the FTIR.

Hydrogen Bonding Interaction between Amide and Alcohols: Dielectric Relaxation and FTIR Study

The dielectric relaxation study for the hydrogen bonded binary system of polar liquid N,N-dimethylacetamide in butanol and pentanol, has been carried out at 11 concentrations over the frequency range of 10 MHz–20 GHz at 303 K using TDR. The least squares fit method has been used to obtain the static dielectric constant (ε0) and relaxation time (τ). By using dielectric parameters the excess permittivity (εE), excess inverses relaxation time (1/τ)E, Kirkwood Correlation factor (g) are also obtained to explore the hydrogen-bonded hetero-molecular interactions. Conformational analysis of the hydrogen bond between the two systems is supported by the FTIR spectra.

Thermodynamics of mixtures with strongly negative deviations from Raoult’s law. XVII. Permittivities and refractive indices for alkan-1-ol + N,N-diethylethanamine systems at (293.15–303.15) K. Application of the Kirkwood-Fröhlich model

Relative permittivities at 1 MHz, εr, at 0.1 MPa and (293.15–303.15) K and refractive indices, nD, at similar conditions have been measured for the alkan-1-ol (methanol, propan-1-ol, butan-1-ol, pentan-1-ol or heptan-1-ol) + N,N-diethylethanamine (TEA) systems. Positive values of the excess permittivities, εrE, are encountered for the methanol system at high alcohol concentrations. The remaining mixtures are characterized by negative εrE values over the whole composition range. At ϕ1 (volume fraction) = 0.5, εrE changes in the order: methanol > propan-1-ol > butan-1-ol < pentan-1-ol < heptan-1-ol. Mixtures formed by alkan-1-ol and an isomeric amine, hexan-1-amine (HxA) or N-propylpropan-1-amine (DPA) or cyclohexylamine, behave similarly. This has been explained in terms of the lower and weaker self-association of longer alkan-1-ols. From the permittivity data, it is shown that: (i) (alkan-1-ol)-TEA interactions contribute positively to εrE; (ii) TEA is an effective breaker of the network of the alkan-1-ols; (iii) structural effects, which are very important for the volumetric and calorimetric data of alkan-1-ol + TEA systems, are also relevant when evaluating dielectric data. This is confirmed by the comparison of εrE measurements for alkan-1-ol + aliphatic amine mixtures; (iv) the aromaticity effect (i.e., the replacement of TEA by pyridine in systems with a given alkan-1-ol) leads to an increase of the mixture polarization. Calculations conducted in the framework of the Kirkwood-Fröhlich model are consistent with the previous statements.

Dielectric relaxation and hydrogen bonding interaction of polyethylene glycol dimethyl ether in water mixture

ABSTRACT The complex permittivity spectra of binary mixtures of polyethylene glycol dimethylether [PEGDME: Molecular Weight 250 g.mol−1 & 500 g.mol−1] with water over entire concentrations and at different temperatures (5ºC, 15ºC and 25ºC) have been measured using time domain reflectometry (TDR) technique in the frequency range of 10–30 GHz. The complex permittivity spectra were fitted in Cole–Davidson model using non-linear least square fit method. The dielectric parameters, such as static dielectric constant and relaxation time, have been determined for PEGDME250+ water and PEGDME500+ water mixtures. The hydrogen bonding interactions for the PEGDME250- water & PEGDME500- water mixtures have been discussed through the determination of excess permittivity, Bruggemann factor and thermodynamic parameters.

Effective Average Correlation Factor and Excess Permittivity for Dielectric Studies on Binary Systems of Phthalates with Alcohols and Nitriles

Effective Average Correlation Factor and Excess Permittivity for Dielectric Studies on Binary Systems of Phthalates with Alcohols and Nitriles

Imaginary optical constants in near-infrared (NIR) spectral range for the separation and discrimination of adulterated diesel oil binary mixtures

Fuel adulteration is a major factor contributing to environmental pollution. The tendency to adulterate diesel oil with kerosene is becoming prevalent in many countries, which is particularly driven by the lower cost of kerosene than of diesel oil. The objective of this study is to develop a method of separating and discriminating between different compositions of kerosene in binary liquid fuel mixtures. In this study, we have utilized refractive indices of binary fuel mixtures measured using an Abbe refractometer, and the inversion of measured transmittance spectra in the visible and near-infrared (NIR) spectral range by a general method based on Kramers–Kronig dispersion analysis, where the singly subtractive Kramers–Kronig relations have been used to obtain the wavelength-dependent imaginary excess permittivity of a binary liquid mixture. The excess permittivity has considerable importance in the interpretation of different liquid molecule interactions in binary liquid mixtures. It is herein demonstrated that the problematic cases of relatively low adulterations of 5% and 10% can be detected and distinguished from 15% adulteration using imaginary optical properties in the NIR spectral range. We show that imaginary optical constants such as excess imaginary permittivity and the extinction coefficient are useful for not only screening for adulteration, but also discriminating and separating low from high kerosene compositions in mixtures. Moreover, these quantities can also be exploited for the development of practical sensors, especially for sensing diesel oil adulteration under field conditions.

Comparative Dielectric Study and Molecular Interactions of Binary Mixtures of (Cyclohexanone + 1-Alkanols) and (Cyclopentanone or Cyclohexanone + Cyclohexanol or Cyclohexane) atT= 298.15 K

Relative permittivities, refractive indices, and densities were measured for binary liquid mixtures of cyclohexanone with 1-alkanols (ethanol, 1-butanol, 1-hexanol, 1-octanol, and 1-decanol) in the mole fraction range of (0 ≤ x2 ≤ 1) at T = 298.15 and p = 101.3 kPa. Another comparative dielectric study was performed on the (cyclohexanone or cyclopentanone + cyclohexanol or cyclohexane) mixtures at the mentioned temperature and pressure. The experimental data were analyzed in terms of the various approaches in order to obtain information about the intermolecular interactions and the mixture structure. The excess properties of different physical quantities confirm the formation of hydrogen-bond structure in these mixtures. For the studied systems, negative excess permittivities and excess Kirkwood correlation factors were obtained, indicating a reduction of the number of effective dipoles in the binary mixtures.

Dielectric relaxation study of aqueous tetraethylene glycol using time domain reflectometry technique in the frequency range 10 MHz to 50 GHz

The Complex permittivity spectra of Tetraethylene glycol(TTEG)-Water mixture over entire concentration range at variant temperatures (0 °C–25 °C) have been determined by Time Domain Reflectometry technique in the frequency range 10 MHz to 50 GHz. The complex permittivity spectra for TTEG- water were fitted in Cole-Davidson model. The Static dielectric constant (ε0), Relaxation time (τ), effective Kirkwood correlation factor (geff), excess permittivity (ε0E), thermodynamic parameters (activation enthalpy and activation entropy) and Bruggeman factor (fB) have been calculated by non-linear least square fit method. The intermolecular interaction between TTEG-Water binary mixture suggest the non-linear behavior of dielectric parameters. The contribution of hydrogen bonding interactions among the solute-solvent mixtures is confirmed by Excess properties and Bruggeman factor.

Studies on the internal structure of the binary mixtures of N,N-dimethylacetamide with 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol and 2-butoxyethanol by means of measuring their densities and relative permittivities at 298.15 K

ABSTRACTThe densities and relative permittivities of binary mixtures of N,N-dimethylacetamide with 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol and 2-butoxyethanol have been measured as a function of composition, at T = 298.15 K. From the experimental data the excess molar volume (VE) from a mole fraction and the excess relative permittivity (εE) from a volume fraction average have been calculated. The results are discussed in terms of intermolecular interactions and structure of studied binary mixtures.

High-frequency dielectric study on the hydrogen bonding interaction on aqueous Cyanoacetamide

The Complex permittivity spectra ε∗(ω) of the mixtures of Cyanoacetamide (CYN) and water in the composition of different mole fractions were achieved in the frequency domain of 10 MHz to 50 GHz at temperatures 25, 20, 15, 10 and 5 °C using Time Domain Reflectometry (TDR) method. The observed values of dielectric spectra can be well defined with the Cole-Davidson relaxation model. The dielectric functions like static dielectric constant (ε0), relaxation time (τ) and Cole Davidson distribution parameter (β) were obtained and also used to determine and discuss the theoretical parameters such as effective Kirkwood Correlation factor (geff), excess dielectric constant ε0E and excess inverse relaxation time ((1/τ)E) to provide information on dipolar alignment and molecular rotation within the solution. Thermodynamic properties such as the free energy of activation (ΔF), the entropy of activation (ΔS∗) and the enthalpy of activation (ΔH∗) were obtained. The free energy of activation is found to be independent of temperature and the average value of free energy is calculated as, 14.28 kJ mol−1. The enthalpy of activation shows the endothermic nature of the reaction. FT-IR results were compared with the Molecular Dynamics (MD) simulation study confirms the formation of the heterogeneous hydrogen-bond network in the solution. The Average Water bridge residual time period and pair interaction energy between the unlike molecules have been determined, also it is confirmed that the higher value of excess permittivity indicates the maximum probability of Hydrogen-bond formation within the system.