Aggregation behavior and electrical properties of amphiphilic pyrrole-tailed ionic liquids in water, from the viewpoint of dielectric relaxation spectroscopy

Soft Matter ◽  
2014 ◽  
Vol 10 (18) ◽  
pp. 3259 ◽  
Author(s):  
Xiaoqing Fan ◽  
Kongshuang Zhao
Keyword(s):  
Ionic Liquids ◽  
Electrical Properties ◽  
Dielectric Relaxation ◽  
Aggregation Behavior ◽  
Dielectric Relaxation Spectroscopy

scholarly journals Water Content Control to Improve Space Charge Storage in a Cork Derivative

2012 ◽  
Vol 730-732 ◽  
pp. 395-400
Author(s):  
M. Carmo Lança ◽  
Inês Cunha ◽  
João Paulo Marques ◽  
Eugen R. Neagu ◽  
Luis Gil ◽  
...  
Keyword(s):  
High Temperature ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Thermal Treatment ◽  
Dielectric Relaxation ◽  
Discharge Current ◽  
Absorption Rate ◽  
Charge Storage ◽  
Dielectric Relaxation Spectroscopy ◽  
Electrical And Dielectric Properties

The influence of humidity content on the electrical and dielectric properties of a composite made from recycled TetraPak® containers and granulated cork was studied. The material components have been dried before preparation and after the composite was conditioned by keeping the samples in a dry environment (desiccator) or in an oven at high temperature (70°C in air). The differences observed in electrical properties (investigated by isothermal charge and discharge current measurement) and dielectric properties (measured using dielectric relaxation spectroscopy) show that the thermal treatment at high temperature is more efficient on removing water and slows down the re-absorption rate.

scholarly journals Dielectric Relaxation in the Hybrid Epoxy/MWCNT/MnFe2O4 Composites

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 697 ◽  
Author(s):  
Darya Meisak ◽  
Jan Macutkevic ◽  
Artyom Plyushch ◽  
Polina Kuzhir ◽  
Algirdas Selskis ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Percolation Threshold ◽  
Dielectric Relaxation ◽  
Electrical Transport ◽  
Hybrid Composites ◽  
Relaxation Times ◽  
Synergetic Effect ◽  
Dielectric Relaxation Spectroscopy ◽  
Low Frequencies

The electrical properties of epoxy/MWCNT (multi-walled carbon nanotubes)/MnFe2O4 hybrid composites loaded with MWCNTs (below, 0.09 vol.%, and above, 0.58 vol.%, percolation threshold) and varying concentrations of MnFe2O4 up to 10 vol.% were studied in a wide frequency range (20 Hz–40 GHz) at different temperatures (20 K–500 K). At low frequencies, the dielectric permittivity and the electrical conductivity of composites with fixed amounts of MWCNT are strongly dependent on MnFe2O4 content. For MWCNT concentrations above the percolation threshold (i.e., 0.58 vol.%), the electrical conductivity highly decreases with the increase of the MnFe2O4 fraction. In contrast, for the epoxy/MWCNT just below the onset of electrical conductivity (0.09 vol.% of MWCNTs), there exists an optimal concentration of MnFe2O4 inclusions (i.e., 0.025 vol.%), leading to a dramatic increase of the electrical conductivity by three orders of magnitude. The electrical transport in composites is mainly governed by electron tunneling at lower temperatures (below 200 K), and it is highly impacted by the matrix conductivity at higher temperatures (above 400 K). The electrical properties were discussed in terms of the Maxwell–Wagner relaxation and distributions of relaxation times. A non-invasive platform based on dielectric relaxation spectroscopy was proposed for enhancing the synergetic effect coursed by using multiple nanoinclusions in polymer composites just below the percolation threshold.

scholarly journals Studies of Polymer Solvation by Dielectric Relaxation Spectroscopy III: Polyvinyl Pyrrolidone in N-Methyl-2-Pyrrolidone, Ethanediol, Methanol, and Water

1990 ◽  
Vol 45 (2) ◽  
pp. 126-134
Author(s):  
E. Dachwitz
Keyword(s):  
Dielectric Relaxation ◽  
Chain Length ◽  
Molar Mass ◽  
Polyvinyl Pyrrolidone ◽  
Dielectric Relaxation Spectroscopy ◽  
Length Effect ◽  
Repeat Units ◽  
Solvent Model ◽  
Spectral Components ◽  
High Concentrations

AbstractThe permittivity of the title solutions has been measured at frequencies between some MHz and 72 GHz at 20 °C. Polyvinyl pyrrolidone of relative molar mass ranging from 1200 to 360 000 has been used. Referring to the concentration of monomeric repeat units (x = 0.65 maximum) there is no significant chain length effect. The permittivity data are described in terms of discrete Debye type spectral components. Special attention is paid to the contributions ascribable to the solvents, which are discussed with respect to their solvation behaviour. This can be described by a three state solvent model as follows. Besides the "bulk" solvent a further contribution is found in any case which is due to loosely affected (slowed down) solvent. Moreover a part of the solvent appears to be tightly bound to the polymer at high concentrations. All the solvents considered show similar solvation properties, notwithstanding their different tendencies towards selfassociation.

High Frequency Dielectric Response of the Ionic Liquid N-Methyl-N-ethylpyrrolidinium Dicyanamide

2007 ◽  
Vol 60 (1) ◽  
pp. 6 ◽  
Author(s):  
Simon Schrödle ◽  
Gary Annat ◽  
Douglas R. MacFarlane ◽  
Maria Forsyth ◽  
Richard Buchner ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Dielectric Loss ◽  
Dielectric Relaxation ◽  
High Frequency ◽  
Dielectric Response ◽  
Room Temperature ◽  
Room Temperature Ionic Liquid ◽  
Dielectric Relaxation Spectroscopy ◽  
Frequency Range ◽  
Fast Rotation

A study of the room-temperature ionic liquid N-methyl-N-ethylpyrrolidinium dicyanamide by dielectric relaxation spectroscopy over the frequency range 0.2 GHz ≤ ν ≤ 89 GHz has revealed that, in addition to the already known lower frequency processes, there is a broad featureless dielectric loss at higher frequencies. The latter is probably due to the translational (oscillatory) motions of the dipolar ions of the IL relative to each other, with additional contributions from their fast rotation.

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