scholarly journals Apparent relaxation-time spectrum cutoff in dilute polymer solutions: An effect of solvent dynamics

2001 ◽  
Vol 39 (22) ◽  
pp. 2860-2873 ◽  
Author(s):  
Steven C. Peterson ◽  
Isabel Echeverría ◽  
Stephen F. Hahn ◽  
Deidre A. Strand ◽  
John L. Schrag
Keyword(s):  
Relaxation Time ◽  
Polymer Solutions ◽  
Time Spectrum ◽  
Relaxation Time Spectrum ◽  
Effect Of Solvent ◽  
Dilute Polymer Solutions ◽  
Solvent Dynamics

Some Aspects of Discrete Relaxation Time Spectra as Obtained from Dynamic Moduli Data

1995 ◽  
Vol 60 (11) ◽  
pp. 1815-1829 ◽  
Author(s):  
Jaromír Jakeš
Keyword(s):  
Relaxation Time ◽  
Least Squares ◽  
Discrete Spectrum ◽  
Integral Transform ◽  
Time Spectrum ◽  
Relaxation Time Spectrum ◽  
Dynamic Moduli ◽  
Best Fitting ◽  
Discrete Spectra ◽  
Well Posed

The problem of finding a relaxation time spectrum best fitting dynamic moduli data in the least-squares sense is shown to be well-posed and to yield a discrete spectrum, provided the data cannot be fitted exactly, i.e., without any deviation of data and calculated values. Properties of the resulting spectrum are discussed. Examples of discrete spectra obtained from simulated literature data and experimental literature data on polymers are given. The problem of smoothing discrete spectra when continuous ones are expected is discussed. A detailed study of an integral transform inversion under the non-negativity constraint is given in Appendix.

Relaxation Time Spectrum, Elasticity, and Viscosity of Rubber. I

1954 ◽  
Vol 27 (1) ◽  
pp. 36-54 ◽  
Author(s):  
W. Kuhn ◽  
O. Künzle ◽  
A. Preissmann
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Time Spectrum ◽  
Test Sample ◽  
Elastic Behavior ◽  
Relaxation Processes ◽  
Relaxation Time Spectrum ◽  
Restoring Force ◽  
Constant Length ◽  
Rapid Deformation

Abstract By rapid deformation of a medium in which linear molecules are present, various changes are produced simultaneously in the latter. These changes are more or less independent of one another, and can release independently and totally or partially by rearrangement of valence distances and valence angles in the chain molecules. By virtue of such relaxation processes, a portion of the stress originating in the rapid deformation disappears, with a changing time requirement for the various portions. A relaxation time spectrum is thus formed. The relaxation time spectrum consists of a finite number of restoring force mechanisms with proper relaxation times or of a continuous spectrum. Both the creep curves (the dependence of the length of a body on time at constant load), and stress relaxation (decay of the stress observed in test sample kept at constant length after rapid deformation), as well as the total visco-elastic behavior, especially the behavior at constant periodic deformation of the test sample, are determined by the relaxation time spectrum. The appropriate Quantitative relationships were derived.

Dynamics of the Relaxation-Time Spectrum in a CuMn Spin-Glass

1983 ◽  
Vol 51 (10) ◽  
pp. 911-914 ◽  
Author(s):  
L. Lundgren ◽  
P. Svedlindh ◽  
P. Nordblad ◽  
O. Beckman
Keyword(s):  
Relaxation Time ◽  
Spin Glass ◽  
Time Spectrum ◽  
Relaxation Time Spectrum

Surface-tension-driven breakup of viscoelastic liquid threads

1982 ◽  
Vol 120 ◽  
pp. 245-266 ◽  
Author(s):  
Simon L. Goren ◽  
Moshe Gottlieb
Keyword(s):  
Relaxation Time ◽  
Stress Relaxation ◽  
Polymer Solutions ◽  
Small Diameter ◽  
Shear Thinning ◽  
Prior History ◽  
Axial Tension ◽  
Dilute Polymer Solutions ◽  
Linearized Stability ◽  
Newtonian Liquids

A linearized stability analysis is carried out for the breakup of small-diameter liquid filaments of dilute polymer solutions into droplets. Oldroyd's 8-constant model expressed in a corotational reference frame is used as the rheological equation of state. The crucial idea in this theory is the recognition that the liquid may be subject to an unrelaxed axial tension due to its prior history. If the tension is zero, the present analysis predicts that jets of shear-thinning liquids are less stable than comparable jets of Newtonian liquids; this is in agreement with previous analyses. However, when the axial tension is not zero, and provided the stress relaxation time constant is sufficiently large, the new theory predicts that the axial elastic tension can be a significant stabilizing influence. With reasonable values for the tension and stress relaxation time the theory explains the great stability observed for jets of some shear- thinning, dilute polymer solutions. The theory explains why drops produced from jets of such liquids are larger than drops from corresponding Newtonian liquids. The theory also appears capable of explaining the sudden appearance of irregularly spaced bulges on jets after long distances of t,ravel with little amplification of disturbances.

The Role of Stochastic Noise on the Glass Transition

1995 ◽  
Vol 407 ◽  
Author(s):  
Fernando C. Perez-Cardenas ◽  
Hao Gan
Keyword(s):  
Relaxation Time ◽  
Glass Transition ◽  
Time Spectrum ◽  
Structure Evolution ◽  
Stochastic Noise ◽  
Relaxation Time Spectrum ◽  
Glass Transition Region ◽  
Type Differential Equation ◽  
Glass Relaxation

ABSTRACTGlasses are amorphous solids that exhibit an intricate structural relaxation. A broad relaxation time spectrum always emerges when these systems are perturbed. By using a Langevin-type differential equation to describe the structure dynamicsof these materials, it is depicted how the broad relaxation time spectrum arises due to the stochastic noise and how this affects the system's structure evolution as it is cooled down into the glass transition region. This stochastic model provides a macroscopic as well a microscopic view of the glass relaxation process.

scholarly journals A revised relaxation-time spectrum for Fennoscandia

1999 ◽  
Vol 139 (1) ◽  
pp. 69-86 ◽  
Author(s):  
K. Wieczerkowski ◽  
J. X. Mitrovica ◽  
D. Wolf
Keyword(s):  
Relaxation Time ◽  
Time Spectrum ◽  
Relaxation Time Spectrum

The relaxation time spectrum of nearly monodisperse polybutadiene melts

1992 ◽  
Vol 31 (1) ◽  
pp. 75-82 ◽  
Author(s):  
M. Baurngaertel ◽  
M. E. De Rosa ◽  
J. Machado ◽  
M. Masse ◽  
H. H. Winter
Keyword(s):  
Relaxation Time ◽  
Time Spectrum ◽  
Relaxation Time Spectrum
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