Dielectric relaxation of 1-nitropropane-ethanol mixtures using pico second time domain technique from 10 MHz to 50 GHz

Complex dielectric measurements in the frequency range 10 MHz - 50 GHz have been carried out in 1-nitropropane-ethanol mixtures with various concentrations by using a time domain reflectometry (TDR) at 283 K to 298 K. The dielectric relaxation response of 1-nitropropane-ethanol mixtures have been analyzed by using Debye model. The dielectric parameters such as static dielectric constant, relaxation time, excess permittivity, excess inverse relaxation time, Kirkwood correlation factor, enthalpy of activation and Gibbs free energy of activation have been determined for 1-nitropropane-ethanol system. The study confirms that the intermolecular interaction varies significantly with the increase in concentration of 1-nitropropane in ethanol

Temperature dependent dielectric relaxation studies of halopropane from 10 Mhz to 50 Ghz using a time domain reflectometry (TDR)

167-170Temperature dependent dielectric relaxation study of halopropane (1-Chloropropane, 1-Bromopropane, 1-Iodopropane) have been carried out in the frequency 10 MHz to 50 GHz using Time domain reflectometry technique. The complex permittivity spectrum has been fitted with single Debye relaxation spectral function. Non-linear square fit method has been used to obtain dielectric parameters such as static dielectric constant (ε0), relaxation time (τ), Kirkwood Correlation factor  and thermodynamic parameters viz. Entropy and enthalpy. The observed properties of Kirkwood correlation (g)and thermodynamic parameters significantly confirm the intermolecular association and hydrogen bonding in halopropanes

Temperature dependent dielectric relaxation studies of halopropane from 10 Mhz to 50 Ghz using a time domain reflectometry (TDR)

Temperature dependent dielectric relaxation study of halopropane (1-Chloropropane, 1-Bromopropane, 1-Iodopropane) have been carried out in the frequency 10 MHz to 50 GHz using Time domain reflectometry technique. The complex permittivity spectrum has been fitted with single Debye relaxation spectral function. Non-linear square fit method has been used to obtain dielectric parameters such as static dielectric constant (ε0), relaxation time (τ), Kirkwood Correlation factor  and thermodynamic parameters viz. Entropy and enthalpy. The observed properties of Kirkwood correlation (g)and thermodynamic parameters significantly confirm the intermolecular association and hydrogen bonding in halopropanes

Molecular interaction studies of isopropyl acetate-xylene mixture using dielectric relaxation approach

72-79Dielectric relaxation parameters of Isopropyl acetate (IPA)-xylene mixtures with different concentrations and temperatures have been measured in the frequency range of 10 MHz to 30 GHz using time domain reflectometry technique. Static dielectric constant, relaxation time, excess permittivity, excess relaxation time, Bruggeman factor, Kirkwood correlation factor and thermodynamic parameters have been determined to understand molecular association between the IPA and xylene molecules. For entire concentrations of IPA-xylene mixture the Kirkwood correlation factor is less than one which shows the antiparallel nature of electric dipole orientation. The experimental values of dielectric constant obtained from time domain reflectometry are in well agreement with theoretical values of dielectric constant obtained by Luzar model. Positive values of enthalpy and entropy indicating that the system is endothermic and less ordered while Gibbs free energy decreases with increase of IPA in xylene

Dielectric relaxation properties of aqueous dimethylamine, trimethylamine and ethylamine using time domain reflectometry technique

The complex permittivity spectra of dimethylamine (40 wt. % in water), trimethylamine (30 wt. % in water) and ethylamine (70 wt. % in water) have been obtained at different temperature using time domain reflectometry technique in the frequency range of 10 MHz-50 GHz. The relaxation mechanism for these systems is described by using Cole-Davidson model. The temperature dependant dielectric relaxation parameters such as static dielectric constant (ε0), relaxation time (τ) and distribution parameter (β) have been obtained by using non-linear least square fit method. The extracted static dielectric constant (ε0) and relaxation time (τ) values have been used to calculate thermodynamic parameter and Kirkwood correlation factor (geff). The enthalpy of activation ∆actH suggests that chemical kinetic is exothermic. Entropy of activation ∆actS suggests that the system is less ordered and Gibbs free energy of activation ∆actG reveals the molecular reorientation for all the three systems. Kirkwood factor for DMA40, TMA30 and EA70 is greater than unity which confirms the hydrogen bond interaction and parallel orientation of dipoles in molecules

Study of Dielectric Relaxation and Hydrogen Bonding Interaction of 1, 4-Butanediol-1, 4-Dioxane Mixture using TDR Technique

The complex permittivity spectra of 1, 4-butanediol -1, 4-dioxane binary mixtures have been measured in the frequency range from 10MHz to 30GHz using the time domain reflectometry (TDR) technique. The complex permittivity spectra show the Cole-Davidson type relaxation. The static dielectric constant and relaxation time at various temperatures have been obtained from complex permittivity spectra by using the nonlinear least squares fit method. The orientation of electric dipoles and solute-solvent interaction in the liquid mixture was confirmed from the excess, Bruggeman, Kirkwood correlation factor and thermodynamic parameters.

Dielectric Relaxation Studies of Cellulose-Water Mixtures Using Time and Frequency Domain Technique

The complex dielectric permittivity of hydroxypropyl methyl cellulose (HPMC)-water mixture was measured by using Time Domain Reflectometry (TDR) and Frequency Domain (LCR) Technique at 25 oC. The complex dielectric permittivity e*(w), complex electrical modulus M*(w), complex electrical conductivity s*(w), loss tangent (tan d), static dielectric constant (ε0) and relaxation time (τ) have been determined for the cellulose-water system