Théorie de l'absorption ultrasonore des solutions micellaires d'amphiphiles. Application à l'effet de la force ionique sur la dynamique d'échange d'amphiphiles entre micelles et solution environnante

1980 ◽  
Vol 58 (17) ◽  
pp. 1780-1787 ◽  
Author(s):  
R. Zana ◽  
S. Yiv
Keyword(s):  
Relaxation Time ◽  
Ionic Strength ◽  
Exchange Process ◽  
Relaxation Method ◽  
Quantitative Interpretation ◽  
Micellar Solutions ◽  
Ultrasonic Absorption ◽  
Micellar Systems ◽  
Ultrasonic Relaxation ◽  
Absorption Measurements

An expression for the amplitude of the ultrasonic relaxation arising from the exchange of amphiphiles between micelles and surrounding solution has been derived on the basis of the same assumptions as used by Aniansson and Wall to obtain the expression of the relaxation time for this process. The derived expression somewhat extends the range of investigation of micellar systems which can be performed by means of the ultrasonic relaxation method. It has been used for the quantitative interpretation of ultrasonic absorption measurements concerning the effect of ionic strength on the dynamics of the exchange process in micellar solutions of potassium decanoate.

Donnan Equilibria in Polymeric Micellar Systems with Weak Polyelectrolyte Shells: The Lowering of the pH Value

1997 ◽  
Vol 62 (11) ◽  
pp. 1730-1736 ◽  
Author(s):  
Petr Munk ◽  
Zdeněk Tuzar ◽  
Karel Procházka
Keyword(s):  
Ionic Strength ◽  
Block Copolymer ◽  
Ph Value ◽  
Electrolyte Solutions ◽  
Hydrogen Ions ◽  
Micellar Systems ◽  
Weak Electrolytes ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Polyelectrolyte Solutions

When two electrolyte solutions are separated and only some of the ions can cross the boundary, the concentrations of these ions are different on both sides of the boundary. This is the well-known Donnan effect. When weak electrolytes are involved, the imbalance includes also hydrogen ions: there is a difference of pH across the boundary and the dissociation of nondiffusible weak electrolytes is suppressed. The effect is very pronounced when the concentration of the weak electrolyte is high and ionic strength is low. The significance of this phenomenon is discussed for polyelectrolyte solutions, and particularly for block copolymer micelles with weak polyelectrolyte shells. The effect is quite dramatic in the latter case.

scholarly journals Ultrasonic absorption measurements in mammalian tissues

1978 ◽  
Vol 63 (S1) ◽  
pp. S13-S13
Author(s):  
S. A. Goss ◽  
L. A. Frizzell ◽  
F. Dunn
Keyword(s):  
Ultrasonic Absorption ◽  
Mammalian Tissues ◽  
Absorption Measurements

Glass Transition and Ultrasonic Relaxation in Polystyrene

1996 ◽  
Vol 455 ◽  
Author(s):  
A. Sahnoune ◽  
L. Piché
Keyword(s):  
Molecular Weight ◽  
Relaxation Time ◽  
Glass Transition ◽  
Low Temperatures ◽  
Relaxation Modulus ◽  
Low Molecular Weight ◽  
Relaxation Model ◽  
Fragility Index ◽  
Molecular Weights ◽  
Ultrasonic Relaxation

ABSTRACTWe present measurements of the glass transition and the ultrasonic relaxation modulus in a series of monodisperse polystyrenes. The temperature dependence of the modulus was analyzed using Havriliak-Negami relaxation model (HN) and Vogel-Tammann-Fulcher equation (VTF) for the relaxation time. The results allowed us to determine the fragility index, m, which decreases with increasing molecular weight, Mn. Furthermore, the relaxation time was found to saturate at high molecular weights and varies as Mnp, in the low molecular weight region. The exponent is p≈2 at high temperatures and p ≈ 7 at low temperatures close to Tg.

Molecular Dynamics of Cellulose-Water Systems Investigated by NMR Relaxation Method

Holzforschung ◽  
2000 ◽  
Vol 54 (5) ◽  
pp. 501-504 ◽  
Author(s):  
K. Banas ◽  
B. Blicharska ◽  
W. Dietrich ◽  
M. Kluza
Keyword(s):  
Molecular Dynamics ◽  
Relaxation Time ◽  
Nmr Relaxation ◽  
Relaxation Method ◽  
Water Systems ◽  
Motion Model ◽  
Cellulose Pulp ◽  
Time Dependencies ◽  
Nmr Relaxation Time ◽  
Different Origin

Summary On the basis of the proton NMR relaxation time dependencies on temperature and frequency in cellulose pulp a simple two-motion model of molecular dynamics has been proposed. The parameters, activation energies and correlation times, describing the model may be correlated with structure features such as level of crystallinity of cellulose with different origin, as well as degree of paper devastation.

Observation of Ultrasonic Relaxation due to Micelle-Monomer Exchange Process in Aqueous Solutions of Rodlike Micelles

2004 ◽  
Vol 43 (5B) ◽  
pp. 2924-2925 ◽  
Author(s):  
Tatsuro Matsuoka ◽  
Yukihiro Masuda ◽  
Tsuyoshi Yamaguchi ◽  
Shinobu Koda
Keyword(s):  
Aqueous Solutions ◽  
Exchange Process ◽  
Ultrasonic Relaxation

A Method of Ultrasonic Absorption Measurements in Liquids

1956 ◽  
Vol 28 (1) ◽  
pp. 152-152
Author(s):  
Roswell P. Barnes ◽  
Robert T. Beyer
Keyword(s):  
Ultrasonic Absorption ◽  
Absorption Measurements
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