Concentration dependent relaxation times of linear polymers in dilute solutions

1984 ◽  
Vol 17 (4) ◽  
pp. 971-973 ◽  
Author(s):  
M. Muthukumar
Keyword(s):  
Relaxation Times ◽  
Linear Polymers ◽  
Dilute Solutions

Relaxation processes of some simple aliphatic molecules in dilute solutions

1977 ◽  
Vol 55 (4) ◽  
pp. 297-301 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Carbon Tetrachloride ◽  
Dielectric Relaxation ◽  
Thermodynamic Parameters ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Dilute Solutions ◽  
Microwave Region ◽  
Nonpolar Solvents ◽  
Dielectric Data ◽  
Intramolecular Rotation

The dielectric relaxation processes of acetone, cyclohexanone, 4-methyl-2-pentanone, and 4-heptanone in dilute nonpolar solvents, n-heptane, cyclohexane, benzene, and carbon tetrachloride have been studied in the microwave region over a temperature range 10 to 60 °C. The relaxation times and the thermodynamic parameters for the activated states have been determined using the measured dielectric data. The results have been discussed in terms of dipole reorientation by molecular and intramolecular rotation and compared, wherever possible, with other similar studies on aliphatic molecules.

The dielectric behaviour of dipolar mixtures I: chlorobenzene–nitrobenzene mixtures

1986 ◽  
Vol 64 (11) ◽  
pp. 1534-1536 ◽  
Author(s):  
F. F. Hanna ◽  
K. N. Abdel-Nour ◽  
A. M. Ghoneim
Keyword(s):  
Relaxation Time ◽  
Thermodynamic Parameters ◽  
Relaxation Times ◽  
Dielectric Behaviour ◽  
Dilute Solutions ◽  
Single Relaxation Time ◽  
Microwave Region ◽  
Dielectric Absorption

The dielectric absorption of dilute solutions of nitrobenzene, chlorobenzene, and their mixtures in cyclohexane and Decalin® have been measured in the microwave region at three temperatures between 20 and 40 °C. The relaxation times and thermodynamic parameters are determined. A single relaxation time is found for the mixtures, and the results are discussed.

The absorption of sound in dilute solutions of 3 He in liquid helium II

1962 ◽  
Vol 268 (1334) ◽  
pp. 424-436 ◽  
Keyword(s):  
Liquid Helium ◽  
Sound Wave ◽  
Relaxation Times ◽  
Temperature Curve ◽  
Dilute Solutions ◽  
Helium Ii ◽  
Temperature Range ◽  
Pure Helium

The coefficient of the absorption of sound in dilute solutions of 3 He in liquid helium II has been measured in the temperature range down to 0.4 °K at a frequency of 14 Mc/s. Results are given for molar concentrations of 3 He of 0.32, 1.6 and 5.2%. In all cases the absorption is less than in pure helium II, and the peak in the absorption-temperature curve is shifted to somewhat lower temperatures. It appears that the 3 He speeds up the interactions between the thermal excitations in the liquid, and thus reduces the second viscosity which is responsible for most of the absorption in pure helium II at the higher temperatures (Khalatnikov 1950; Dransfeld, Newell & Wilks 1958). Our results are compared with a calculation of this effect due to Andreev (1961). At lower temperatures the absorption arises through a different mechanism, and a treatment taking into account the fact that all the relaxation times are long compared to the period of the sound wave has been given by Dransfeld (1958, 1962). Our results are consistent with, and give support to, Dransfeld’s treatment which involves the ‘bunching’ of the thermal phonons by the sound wave.

Dynamics of linear polymers in dilute solutions

1999 ◽  
Vol 246 (1-3) ◽  
pp. 335-345 ◽  
Author(s):  
Ryszard Szorek
Keyword(s):  
Linear Polymers ◽  
Dilute Solutions

Viscoelastic Properties of Rubber Networks

1975 ◽  
Vol 48 (5) ◽  
pp. 981-994 ◽  
Author(s):  
P. Thirion
Keyword(s):  
Viscoelastic Properties ◽  
Dynamic Properties ◽  
Mechanical Energy ◽  
Filler Particle ◽  
Polymer Networks ◽  
Relaxation Times ◽  
Low Frequency ◽  
Linear Polymers ◽  
Approach To Equilibrium ◽  
Sinusoidal Vibration

Abstract The molecular theory of Rouse, Zimm, and Bueche correctly accounts for the viscoelastic properties of polymers in very dilute solution and, to a large extent, for those of polymers in bulk or in concentrated solution, as long as their mean molecular weight is below about 20 000. Above this MW limit, relaxation times appear which are longer than those provided for in this theory. The “viscoelastic plateau”, which then appears in the long relaxation time region of the dynamic spectrum, is ascribed to entanglements of molecular chains which behave like temporary crosslinks. An analogous phenomenon occurs in the same way in permanent polymer networks, such as rubber vulcanizates. In this case one finds abnormally slow relaxation or creep rates during the approach to equilibrium, as well as increased low-frequency mechanical energy losses under forced sinusoidal vibration. The presence of colloidal fillers, such as carbon blacks used to reinforce rubbers, also seems to increase this hysteresis within the polymer matrix, independent of thixotropic effects which result from the reversible rupture of filler particle aggregates under large-amplitude cyclic deformations. We propose to analyze here the results (obtained jointly at the Institut Français du Caoutchouc and at the laboratory of Professor J. D. Ferry, University of Wisconsin) of measurements over the entire rubbery spectrum of the dynamic properties and of stress relaxation on vulcanizates of natural rubber, cis-polybutadiene, and styrene-butadiene copolymer (SBR) in the absence of secondary crystallization or aging phenomena. Then we examine the interpretation of the behavior of these materials, both at low frequency and during the approach to equilibrium, by analogy with the theories of the “viscoelastic plateau” of linear polymers.

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