Dielectric and Association Behavior of 1-Propanol, 2-Propen-1-ol, and 2-Propyn-1-ol in Non-polar Solvents

1972 ◽  
Vol 50 (1) ◽  
pp. 99-103 ◽  
Author(s):  
G. E. Rajala ◽  
J. Crossley
Keyword(s):  
Relaxation Times ◽  
Low Frequency ◽  
Alcohol Concentration ◽  
Dielectric Constants ◽  
Polar Solvents ◽  
Association Behavior

Dielectric constants and losses of 1-propanol, 2-propen-1-ol, and 2-propyn-1-ol in p-xylene, and 1-propanol and 2-propen-1-ol in cyclohexane have been measured at up to 10 frequencies in the range 1–145 GHz at 25 °C. The low frequency dielectric constants have also been measured at 2 MHz. An analysis in terms of two relaxation times has been obtained for each system. The short relaxation times are relatively independent of the alcohol, its concentration, and the solvent. Conversely, the longer relaxation times lengthen with increased alcohol concentration, lengthen in the order 2-propyn-1-ol, 2-propen-1-ol, 1-propyn-1-ol and are considerably shorter in p-xylene than in cyclohexane.

Dielectric Relaxation of the Butyl Alcohols in p-Xylene Solution

1971 ◽  
Vol 49 (5) ◽  
pp. 712-718 ◽  
Author(s):  
John Crossley
Keyword(s):  
Dielectric Relaxation ◽  
Relaxation Times ◽  
Alcohol Concentration ◽  
Dielectric Constants ◽  
Pure Liquid ◽  
Frequency Range ◽  
Concentrated Solutions ◽  
Polar Solvents ◽  
Symmetrical Distribution ◽  
Xylene Solution

Dielectric constants and losses of the four butyl alcohols have been measured at concentrations of 0.02–0.12 mol fraction in p-xylene solution over the frequency range 1–35 GHz at 25 °C. The data for the most dilute solutions can be represented by a symmetrical distribution of relaxation times. For the mole concentrated solutions the Cole–Cole plots indicate a separation into two absorption regions and the data can be analyzed in terms of two relaxation times both of which lengthen with increased alcohol concentration. The contribution from the long relaxation time and the apparent dipole moment for each butanol, is independent of alcohol concentration and decreases in the order n-butanol > iso-butanol > sec-butanol > t-butanol. The results are discussed in terms of previous dielectric relaxation studies of pure liquid aliphatic alcohols and their solutions in non-polar solvents.

Evidence for helical structures in poly(l-olefin sulfones) by TEM

1992 ◽  
Vol 50 (1) ◽  
pp. 276-277
Author(s):  
George C. Ruben ◽  
W.H. Stockmayer
Keyword(s):  
Relaxation Times ◽  
Low Frequency ◽  
Structural Features ◽  
Dielectric Dispersion ◽  
Conformational Behavior ◽  
Helical Structures ◽  
Polar Solvents ◽  
Chain Conformations ◽  
Direct Recognition ◽  
Crucial Experiments

Advances in the techniques of TEM, including the preparation of ultrathin vertically shadowed platinum-carbon (Pt-C) replicas, have allowed the direct recognition of single-structural features, such as DNA , pectin helices or polysiloxane polymers. Here we report some observations on the chain conformations of serval poly (olefin sulfones). We find strong evidence for the presence of some helical conformations, which had been inferred for over a decade but could not so far be established by other methods.Unusual conformational behavior of poly(olefin sulfones) was indicated over twenty-five years ago. Dilute solutions of several poly (1-olefin sulfones), [-CH2-CHR-S02-]X, in non-polar solvents exhibited unexpectedly strong low-frequency dielectric dispersion, with relaxation times typical of rigid tumbling or of the terminal normal mode. In contrast, polysulfones made from olefins with internal double bonds show no low-frequency dielectric loss. To explain these facts, we refer to the crucial experiments of Fawcett and Fee (1982), who prepared terpolymers of 1-hexene,

Dielectric Relaxation Studies of Silver Nanoparticles dispersed Liquid Crystal

2015 ◽  
Vol 8 (3) ◽  
pp. 2176-2188 ◽  
Author(s):  
Keisham Nanao Singh
Keyword(s):  
Activation Energy ◽  
Silver Nanoparticles ◽  
Liquid Crystal ◽  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Relaxation Times ◽  
Low Frequency ◽  
Bulk Liquid ◽  
Molecular Rearrangement ◽  
Relaxation Studies

This article reports on the Dielectric Relaxation Studies of two Liquid Crystalline compounds - 7O.4 and 7O.6 - doped with dodecanethiol capped Silver Nanoparticles. The liquid crystal molecules are aligned homeotropically using CTAB. The low frequency relaxation process occurring above 1 MHz is fitted to Cole-Cole formula using the software Dielectric Spectra fit. The effect of the Silver Nanoparticles on the molecular dipole dynamics are discussed in terms of the fitted relaxation times, Cole-Cole distribution parameter and activation energy. The study indicate a local molecular rearrangement of the liquid crystal molecules without affecting the order of the bulk liquid crystal molecules but these local molecules surrounding the Silver Nanoparticles do not contribute to the relaxation process in the studied frequency range. The observed effect on activation energy suggests a change in interaction between the nanoparticles/liquid crystal molecules.

scholarly journals Determination of the Distribution of Relaxation Times by Means of Pulse Evaluation for Offline and Online Diagnosis of Lithium-Ion Batteries

Batteries ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 36
Author(s):  
Erik Goldammer ◽  
Julia Kowal
Keyword(s):  
Lithium Ion Batteries ◽  
Electrochemical Impedance ◽  
Sampling Rate ◽  
Relaxation Times ◽  
Low Frequency ◽  
Lithium Ion ◽  
Battery Management ◽  
Time Constants ◽  
Time Domain Data ◽  
Aging Study

The distribution of relaxation times (DRT) analysis of impedance spectra is a proven method to determine the number of occurring polarization processes in lithium-ion batteries (LIBs), their polarization contributions and characteristic time constants. Direct measurement of a spectrum by means of electrochemical impedance spectroscopy (EIS), however, suffers from a high expenditure of time for low-frequency impedances and a lack of general availability in most online applications. In this study, a method is presented to derive the DRT by evaluating the relaxation voltage after a current pulse. The method was experimentally validated using both EIS and the proposed pulse evaluation to determine the DRT of automotive pouch-cells and an aging study was carried out. The DRT derived from time domain data provided improved resolution of processes with large time constants and therefore enabled changes in low-frequency impedance and the correlated degradation mechanisms to be identified. One of the polarization contributions identified could be determined as an indicator for the potential risk of plating. The novel, general approach for batteries was tested with a sampling rate of 10 Hz and only requires relaxation periods. Therefore, the method is applicable in battery management systems and contributes to improving the reliability and safety of LIBs.

Effects of director rotation relaxation on viscoelastic wave dispersion in nematic elastomer beams

2018 ◽  
Vol 24 (4) ◽  
pp. 1103-1115 ◽  
Author(s):  
Dong Zhao ◽  
Ying Liu
Keyword(s):  
Wave Motion ◽  
Relaxation Times ◽  
Low Frequency ◽  
Wave Dispersion ◽  
Frequency Limit ◽  
Anisotropic Parameter ◽  
Acoustic Design ◽  
Phase Velocities ◽  
Nematic Elastomer ◽  
Viscoelastic Wave

In this paper, the transverse wave dispersion in a nematic elastomer (NE) Timoshenko beam is studied by considering anisotropy and viscoelasticity of NEs in the low frequency limit. Firstly, the characteristic equations of wave motion in an NE beam are derived, and then numerically solved to obtain the corresponding phase velocities and attenuation factors. The influences of anisotropic parameter, director rotation and rubber relaxation times on the wave dispersion in an NE beam are discussed. Results show that unlike the situation in general isotropic viscoelastic beam, non-classical viscoelastic wave dispersion is found in NE beams. Geometric dispersion is restrained with the vanishing of cut-off frequencies for shear waves due to director rotation relaxation of NEs. This unique property promises prospective applications of NE beams in optic or acoustic design.

Time Domain Zero Field NMR and NQR

1986 ◽  
Vol 41 (1-2) ◽  
pp. 440-444 ◽  
Author(s):  
A. Bielecki ◽  
D. B. Zax ◽  
A. M. Thayer ◽  
J. M. Millar ◽  
A. Pines
Keyword(s):  
Time Domain ◽  
Relaxation Times ◽  
Low Frequency ◽  
High Sensitivity ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Zero Field ◽  
Spin Lattice ◽  
Field Cycling ◽  
The Time Domain

Field cycling methods are described for the time domain measurement of nuclear quadrupolar and dipolar spectra in zero applied field. Since these techniques do not involve irradiation in zero field, they offer significant advantages in terms of resolution, sensitivity at low frequency, and the accessible range of spin lattice relaxation times. Sample data are shown which illustrate the high sensitivity and resolution attainable. Comparison is made to other field cycling methods, and an outline of basic instrumental requirements is given.

Magnetic Aftereffect Due to Hydrogen in NdCo5

1973 ◽  
Vol 51 (23) ◽  
pp. 2407-2414 ◽  
Author(s):  
I. Maartense
Keyword(s):  
Single Crystals ◽  
Relaxation Times ◽  
Low Frequency ◽  
Unknown Origin ◽  
Arrhenius Relation ◽  
Magnetic Aftereffect

In single crystals of NdCo5 containing small amounts of hydrogen, a.c. susceptibility measurements reveal disaccommodation effects and low frequency loss peaks between 130 and 220 °K. Relaxation times, measured over ~5 decades, fit an Arrhenius relation of the form τ = τ0 exp (E/kT), with E = 0.40 ± 0.02 eV and τ0 = 10−12.3 ± 0.4 s. Hydrogen can be introduced by exposing the sample to the gas, or by etching it in acids; it can be removed by heating in a vacuum at ~750 °K. In the degassed material, additional relaxations, of unknown origin, are found near 375 and 720 °K, with E = 0.7 ± 0.1 and 1.6 ± 0.3 eV respectively. The possible importance of these effects to the coercivity of RCo5 compounds is pointed out.

scholarly journals Dielectric Constants of a Binary Solution Near the Critical Solution Temperature

1973 ◽  
Vol 51 (4) ◽  
pp. 545-550 ◽  
Author(s):  
I. Lubezky ◽  
R. McIntosh
Keyword(s):  
High Frequency ◽  
Binary Solution ◽  
Critical Concentration ◽  
Low Frequency ◽  
Dielectric Constants ◽  
Solution Temperature ◽  
Dielectric Losses ◽  
Theoretical Studies ◽  
Critical Solution Temperature ◽  
Experimental Knowledge

The dielectric constants and dielectric losses of solutions of nitrobenzene and 2,2,4-trimethyl pentane have been measured near the critical solution temperature over a concentration range of 22–75% by weight and in the frequency regions of 5–60 and 1000 – 4000 kHz. It was found that below a critical concentration of 35% maxima existed in ε′ and ε″ at a temperature of 0.3 °C above the critical solution temperature. At higher concentrations the maxima disappeared and phase separation was preceded only by changes in the thermal coefficients dε′/dT and dε″/dT. The present study combined with others indicates that two regions of loss exist for the system near the critical temperature: low frequency losses of a conductive nature and high frequency losses of the Debye type. The published experimental knowledge of such systems remains insufficient to enable a thorough test of the theoretical studies published recently by Snider.

Dielectric relaxation of dihalobenzenes. I. Ortho and meta Cl2, Br2, and I2 in benzene solution

1968 ◽  
Vol 46 (24) ◽  
pp. 2745-2748 ◽  
Author(s):  
Abhai Mansingh ◽  
David B. McLay
Keyword(s):  
Benzene Solution ◽  
Relaxation Times ◽  
Dielectric Constants ◽  
Cole Plot ◽  
Molecular Reorientation ◽  
Dielectric Data ◽  
Distribution Parameters ◽  
Order Of Magnitude ◽  
The Right ◽  
Right Order

Dielectric data have been measured for the dilute solutions in benzene at 20.0 °C of the ortho- and meta-isomers of dichlorobenzene, dibromobenzene, and diiodobenzene. The "static" dielectric constants have been measured at 100 kHz, the dielectric constants and losses have been measured at both 9.06 and 21.00 GHz, and the refractive indices have been measured at optical wavelengths. Cole–Cole plots can be fitted to the data to yield mean relaxation times τ0 and distribution parameters α. The values of the relaxation times in the ortho-isomers are 11.8, 14.9, and 20.6 ps for dichlorobenzene, dibromobenzene, and diiodobenzene respectively. The corresponding values for the meta-isomers are 8.6, 10.7, and 13.5 ps respectively, values which increase in the same direction with halogen substituent but which are significantly smaller than the relaxation times for the other isomers. All of these times are of the right order of magnitude for molecular reorientation and there is no evidence for dipole–dipole interactions. Although the nonzero values of the distribution parameters will allow mathematical descriptions in terms of two relaxation times τ1 and τ2, the values derived from two such descriptions yield two unrealistic relaxation times for each molecule. It is concluded that the analysis based on the Cole–Cole plot gives the most meaningful results.

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