scholarly journals Microwave Dielectric Study of Tetramethylurea andN, N-Dimethylacetamide Binary Mixture in Benzene

2011 ◽  
Vol 8 (3) ◽  
pp. 1378-1386
Author(s):  
V. Sharma ◽  
N. Thakur
Keyword(s):  
Dielectric Constant ◽  
Binary Mixture ◽  
Dielectric Relaxation ◽  
Benzene Solution ◽  
Microwave Frequency ◽  
Single Frequency ◽  
Rate Theory ◽  
Dielectric Study ◽  
Frequency Method ◽  
Dielectric Parameters

Dielectric relaxation of the binary mixture of tetramethylurea andN, N-dimethylacetamide has been studied at fixed frequency and temperature (9.88 GHz & 298 K respectively) in benzene solution. Different dielectric parameters like the dielectric constant (ε') and the dielectric loss (ε") at microwave frequency, static dielectric constant (ε0) and dielectric constant (ε∞) at optical frequency were determined. The values of relaxation time (τ(1), τ(2), τ(0)& τGK) have been calculated using higasi’s single frequency method and Gopala Krishna’s method. Using Eyring’s rate theory, the activation energies for the process of dielectric relaxation and viscous flow were calculated and compared. The study of dielectric properties of the binary mixture reveals the existence of the solute-solute type of molecular associations.

Dielectric Relaxation Studies of Ternary Mixture of Dimethyl Phthalate and Heptanol in Benzene Solution in the Microwave Region

2015 ◽  
Vol 70 (7) ◽  
pp. 507-512
Author(s):  
A. Mushtaq Ahmed Khan ◽  
M. Subramanian
Keyword(s):  
Dielectric Constant ◽  
Dipole Moment ◽  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Benzene Solution ◽  
Microwave Frequency ◽  
Viscous Force ◽  
Dimethyl Phthalate ◽  
Flow Process ◽  
Relaxation Studies

AbstractThe molecular structure and molecular forces in liquids and solutions, in particular, have been investigated by dielectric relaxation studies. The nature and strength of the molecular interactions have been established as the main cause for the chemical behaviour of compounds. The dielectric behaviour of dimethyl phthalate with heptanol in benzene solution has been studied at a microwave frequency of 9.36 GHz at different temperatures 303, 308, and 313 K. Different dielectric quantities such as dielectric constant (ε′), dielectric loss (ε″), static dielectric constant (ε0), and dielectric constant at optical frequency (ε∞) have been determined. The relaxation time τ has been calculated by both Higasi’s method and Cole–Cole method. The dielectric relaxation process can be treated as a rate process just like the viscous flow process. The complex system investigated shows the maximum relaxation time values at high temperatures by both Higasi’s method and Cole–Cole method. The molar free energies of activation of dipole moment (ΔFτ) and viscous force (ΔFη) have also been reported. The excess dipole moment is also determined. The excess dipole moment is a qualitative index for the presence of a hydrogen bond in the ternary system. The value of Δμ obtained in our study indicates the presence of hydrogen bonds between the components of the mixture. The system investigated shows that the relaxation time value increases with the increase in the concentration of solute.

Dielectric Relaxation of Binary Mixtures of Tetrahydrofuran and N-Methylformamide in Benzene Solution Using Microwave Absorption Studies

2010 ◽  
Vol 65 (1-2) ◽  
pp. 141-144 ◽  
Author(s):  
Raman Kumar ◽  
Raman Kumar ◽  
Vir S. Rangra
Keyword(s):  
Binary Mixture ◽  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Binary Mixtures ◽  
Benzene Solution ◽  
Relaxation Times ◽  
Single Frequency ◽  
Flow Process ◽  
Dielectric Relaxation Process ◽  
C 30

AbstractUsing standard standing wave microwave X-band technique and following Gopala Krishna’s single frequency (9.90 GHz) concentration variational method, the dielectric relaxation times τ and the dipole moments μ of dilute solutions of Tetrahydrofuran (THF), N-methylformamide (NMF), and THF+NMF binary mixtures in benzene solutions have been calculated at different temperatures (25°C, 30°C, 35°C, and 40°C). The energy parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process for the THF+NMF binary mixture containing 30 mol% THF have been calculated at 25°C, 30°C, 35°C, and 40°C and compared with the corresponding viscosity parameters. A good agreement between the free energy of activation from these two sets of values shows that the dielectric relaxation process like the viscous flow process can be treated as a rate process. From relaxation time behaviour of THF and NMF binary mixture in benzene solution, solute-solute types of the molecular association has been proposed.

scholarly journals Dielectric Relaxation Studies of Hydrogen Bonded Complexes of Benzamide and Acetamide with 4-substituted Phenols Using X-band Microwave Frequency

2021 ◽  
Vol 38 (3) ◽  
Author(s):  
A. Aathif Basha ◽  
F. Liakath Ali Khan
Keyword(s):  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Proton Donor ◽  
Single Frequency ◽  
Hydroxyl Group ◽  
Molar Ratio ◽  
Frequency Method ◽  
Dielectric Parameters ◽  
Bonded Complexes ◽  
Hydrogen Bonded

At 308 K, using a 9.37 GHz dielectric relaxation setup, dielectric studies of hydrogen bonded complexes of benzamide and acetamide with 4-fluorophenol, 4-bromophenol, 4-chlorophenol, and 4-iodophenol in benzene were performed. Various dielectric parameters (such as ??, ??, ?0, and ??) were tested. The steric interactions of the proton donor determined the group rotation relaxation time t(2), whereas the significance of Higasi’s single frequency method for multiple relaxation time t(1) was determined by the hydrogen bonding power of the phenolic hydrogen. The presence of a 1:1 complex system between the prepared samples, as well as a charge transfer between the free hydroxyl group of phenols and the carbonyl group of amides was confirmed by the fact that the relaxation time and molar free energy activation of the 1:1 molar ratio were greater than some other higher molar ratios (i.e. 3:1, 2:1, 1:2, 1:3).

Dielectric Relaxation Based on Adsorbed Water in Wood Cell Wall under Non-Equilibrium State. Part 3. Desorption

Holzforschung ◽  
2002 ◽  
Vol 56 (6) ◽  
pp. 655-662 ◽  
Author(s):  
C. Jinzhen ◽  
Z. Guangjie
Keyword(s):  
Dielectric Constant ◽  
Dielectric Relaxation ◽  
Adsorbed Water ◽  
Second Step ◽  
Relaxation Processes ◽  
Relaxation Time Distribution ◽  
Dielectric Parameters ◽  
Frequency Spectra ◽  
Desorption Process ◽  
Content Change

Summary The temperature and frequency spectra of dielectric constant ε′ and dielectric loss factor ε″ of Sikkim spruce (Picea spinulosa Griff.) were measured to investigate the change in dielectric relaxation of water in wood during desorption. In order to control the rate of moisture content change, the measurements were carried out in three steps: from fiber saturation point to 80% RH, from 80% RH to 60% RH and from 60% RH to 20% RH, at 25°C. Two dielectric relaxation processes were observed in different temperature and frequency regions which changed their position and strength with the desorption process. Using the ε′ and ε″ spectra, two groups of Cole-Cole plots were obtained, on which basis two groups of dielectric parameters including the static dielectric constant εS, optic dielectric constant ε∞, relaxation strength (εS–ε∞), and the relaxation time distribution coefficient α were calculated. Both groups of parameters showed similar trends, that is, ε∞ remained nearly constant during the whole desorption process. εS and (εS–ε∞)changed little during the first step of desorption, decreased obviously during the second step and declined slightly during the third step. The α value obtained from the lower frequency data changed significantly during the second and third desorption steps, while there was little change in the other group of α values. These differences can be explained by different mechanisms of the relaxation processes in the lower and higher frequency regions.

scholarly journals Comparative Dielectric Study of Binary Mixtures of Coriandar oil and Radish oil

2021 ◽  
Vol 37 (2) ◽  
pp. 308-313
Author(s):  
Mohammad Shafi Khan ◽  
Vishal Singh Chandel ◽  
Satyendra Pratap Singh
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Binary Mixtures ◽  
Dielectric Study ◽  
Dielectric Parameters ◽  
Temperature Controller ◽  
Different Temperatures

The present paper deals with the dielectric study (dielectric constant, dielectric loss) of two medicinal oils, coriandar and radish oil and their binary mixtures at different temperatures and frequencies. HP 4194A impedance gain/phase analyzer and temperature controller (Julabo, model number F-25, microprocessor controlled) were used for determination of dielectric parameters and maintaining the temperature of pure oils their binary mixtures.

Dielectric Study of Carboxyl (–COOH) Functionalized Multi-Walled Carbon Nano Tube-Silicone Oil Nanofluids at Different Temperatures

2019 ◽  
Vol 17 (12) ◽  
pp. 982-986
Author(s):  
M. Premalatha ◽  
N. Preetha ◽  
S. Padmavathi ◽  
A. Kingson Solomon Jeevaraj
Keyword(s):  
Dielectric Constant ◽  
Dipole Moment ◽  
Silicone Oil ◽  
Dielectric Study ◽  
Dielectric Parameters ◽  
Entire Concentration Range ◽  
Molar Polarization ◽  
Different Temperatures ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

In this work, dielectric properties of carboxyl (–COOH) functionalized MWCNTs-Silicone oil (polydimethylsiloxanes) nanofluids have been studied at static frequency. Purchased carboxyl (–COOH)-f-multi-walled carbon nanotubes (MWCNTs) are purchased and characterized using transmission electron microscopy (TEM) technique. Carboxyl (–COOH)-f-MWCNT-Silicone oil nanofluids are prepared by dispersing COOH-MWCNT in Silicone oil (base fluid) with the help of probe sonicator. At various concentrations and at different temperatures dielectric parameters like static dielectric constant (ɛ0), excess dielectric constant (ɛE), dipole moment (μ), excess dipole moment (μE) and molar polarization (P) have been determined for COOH-f-MWCNT-Silicone oil nanofluids. The changes in the dielectric parameters with respect to five different concentrations and various temperatures (303 K to 323 K) are analyzed in the presence of intermolecular interactions happening in the COOH-f-MWCNT-Silicone oil nanofluid system. Excess dielectric constant and excess dipole moment values are found to be negative over entire concentration range of COOH-MWCNTs at every different temperature.

Dielectric Relaxation Studies of Mixtures of N-Methylacetamide and Ethanol in Benzene Solutions Using Microwave Absorption Technique

2007 ◽  
Vol 62 (3-4) ◽  
pp. 213-217 ◽  
Author(s):  
Raman Kumar ◽  
Vir Singh Rangra ◽  
Dhani Ram Sharma ◽  
Nagesh Thakur ◽  
Nainjeet Singh Negi
Keyword(s):  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Binary Mixtures ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Activation Parameters ◽  
Single Frequency ◽  
Dielectric Relaxation Process ◽  
Free Energy Of Activation

Using standard standing wave microwave X-band techniques, and by following Gopala Krishna’s single frequency (9.90 GHz) concentration variational method, the dielectric relaxation times (τ) and dipole moments (μ) of binary mixtures of different molar concentrations of ethanol (EtOH) in binary mixtures of N-methylacetamide (NMA) and ethanol in benzene solutions at 25, 30, 35 and 40 ◦C have been calculated. The activation parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process of binary mixtures containing 30 mol% of EtOH have been calculated at 25, 30, 35 and 40 ◦C and compared with the corresponding viscosity parameters. A good agreement between the free energy of activation from these two sets of values shows that the dielectric relaxation process, like the viscous flow, can be treated as a rate process. From relaxation time behaviour of NMA and EtOH binary mixtures in benzene solution, solute-solute and solute-solvent types of the molecular association have been predicted.

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