Structural Relaxation and Dynamic Heterogeneity in a Polymer Melt at Attractive Surfaces

2003 ◽  
Vol 90 (22) ◽  
Author(s):  
Grant D. Smith ◽  
Dmitry Bedrov ◽  
Oleg Borodin
Keyword(s):  
Structural Relaxation ◽  
Polymer Melt ◽  
Dynamic Heterogeneity

scholarly journals Predictive relation for the α-relaxation time of a coarse-grained polymer melt under steady shear

2020 ◽  
Vol 6 (17) ◽  
pp. eaaz0777 ◽  
Author(s):  
Andrea Giuntoli ◽  
Francesco Puosi ◽  
Dino Leporini ◽  
Francis W. Starr ◽  
Jack F. Douglas
Keyword(s):  
Relaxation Time ◽  
Structural Relaxation ◽  
Polymer Melt ◽  
Steady Shear ◽  
Coarse Grained ◽  
Scattering Function ◽  
Dynamic Heterogeneity ◽  
Shear Rates ◽  
Wide Range ◽  
Intermediate Scattering Function

We examine the influence of steady shear on structural relaxation in a simulated coarse-grained unentangled polymer melt over a wide range of temperature and shear rates. Shear is found to progressively suppress the α-relaxation process observed in the intermediate scattering function, leading ultimately to a purely inertially dominated β-relaxation at high shear rates, a trend similar to increasing temperature. On the basis of a scaling argument emphasizing dynamic heterogeneity in cooled liquids and its alteration under material deformation, we deduce and validate a parameter-free scaling relation for both the structural relaxation time τα from the intermediate scattering function and the “stretching exponent” β quantifying the extent of dynamic heterogeneity over the entire range of temperatures and shear rates that we can simulate.

Time scale of dynamic heterogeneity in model ionic liquids and its relation to static length scale and charge distribution

2015 ◽  
Vol 17 (43) ◽  
pp. 29281-29292 ◽  
Author(s):  
Sang-Won Park ◽  
Soree Kim ◽  
YounJoon Jung
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Charge Distribution ◽  
Power Law ◽  
Structural Relaxation ◽  
Time Scale ◽  
Length Scale ◽  
Dynamic Heterogeneity ◽  
General Power

We find a general power-law behavior: , where ζdh ≈ 1.2 for all the ionic liquid models, regardless of charges and the length scale of structural relaxation.

scholarly journals Investigating the influence of different thermodynamic paths on the structural relaxation in a glass-forming polymer melt

1999 ◽  
Vol 11 (10) ◽  
pp. 2179-2192 ◽  
Author(s):  
Christoph Bennemann ◽  
Wolfgang Paul ◽  
Jörg Baschnagel ◽  
Kurt Binder
Keyword(s):  
Structural Relaxation ◽  
Polymer Melt ◽  
Glass Forming

Polymer Morphology Revealed by Staining Techniques

1981 ◽  
Vol 39 ◽  
pp. 340-341
Author(s):  
A. C. Reimschuessel ◽  
V. Kramer
Keyword(s):  
Polymer Melt ◽  
Nylon 6 ◽  
Morphological Features ◽  
Negative Staining ◽  
Polymer Morphology ◽  
Crystallizable Polymer ◽  
Staining Techniques ◽  
Long Chain

Staining techniques can be used for either the identification of different polymers or for the differentiation of specific morphological domains within a given polymer. To reveal morphological features in nylon 6, we choose a technique based upon diffusion of the staining agent into accessible regions of the polymer.When a crystallizable polymer - such as nylon 6 - is cooled from the melt, lamellae form by chainfolding of the crystallizing long chain macromolecules. The regions between adjacent lamellae represent the less ordered amorphous domains into which stain can diffuse. In this process the lamellae will be “outlined” by the dense stain, giving rise to contrast comparable to that obtained by “negative” staining techniques.If the cooling of the polymer melt proceeds relatively slowly - as in molding operations - the lamellae are usually arranged in a radial manner. This morphology is referred to as spherulitic.

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