Crystallization of Poly(l-lactic acid) Probed with Dielectric Relaxation Spectroscopy

2006 ◽  
Vol 39 (19) ◽  
pp. 6513-6520 ◽  
Author(s):  
Ana Rita Brás ◽  
María Teresa Viciosa ◽  
Yaming Wang ◽  
Madalena Dionísio ◽  
João F. Mano
Keyword(s):  
Lactic Acid ◽  
Dielectric Relaxation ◽  
Dielectric Relaxation Spectroscopy

Influence of Crystallinity in Molecular Motions of Poly(l-lactic acid) Investigated by Dielectric Relaxation Spectroscopy

2008 ◽  
Vol 41 (17) ◽  
pp. 6419-6430 ◽  
Author(s):  
A. R. Brás ◽  
P. Malik ◽  
M. Dionísio ◽  
J. F. Mano
Keyword(s):  
Lactic Acid ◽  
Dielectric Relaxation ◽  
Dielectric Relaxation Spectroscopy ◽  
Molecular Motions

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.

Broadband Dielectric Relaxation Spectroscopy in Polymer Nanocomposites

2008 ◽  
Vol 265 (1) ◽  
pp. 12-20 ◽  
Author(s):  
Polycarpos Pissis ◽  
Daniel Fragiadakis ◽  
Athanasios Kanapitsas ◽  
Kostas Delides
Keyword(s):  
Dielectric Relaxation ◽  
Polymer Nanocomposites ◽  
Dielectric Relaxation Spectroscopy
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