scholarly journals Tension thickening, molecular shape, and flow birefringence of an H-shaped polymer melt in steady shear and planar extension

2010 ◽  
Vol 132 (1) ◽  
pp. 014904 ◽  
Author(s):  
Chunggi Baig ◽  
Vlasis G. Mavrantzas
Keyword(s):  
Polymer Melt ◽  
Molecular Shape ◽  
Flow Birefringence ◽  
Steady Shear ◽  
Planar Extension

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.

scholarly journals A study on the flow birefringence of polymer melt.

1988 ◽  
Vol 54 (508) ◽  
pp. 2123-2127
Author(s):  
Tokuyuki HONDA ◽  
Hirosi TAMAKI ◽  
Yukio HORI
Keyword(s):  
Polymer Melt ◽  
Flow Birefringence

scholarly journals Investigation of Vortex Development during Polymer Melt Flows by Flow Birefringence

2011 ◽  
Author(s):  
Jan Musil ◽  
Martin Zatloukal ◽  
Tim Gough ◽  
Mike Martyn ◽  
Martin Zatloukal
Keyword(s):  
Polymer Melt ◽  
Flow Birefringence

Flow birefringence of flexible polymer chains in steady shear flow: a Brownian dynamics simulation

1993 ◽  
Vol 26 (15) ◽  
pp. 3851-3857 ◽  
Author(s):  
K. D. Knudsen ◽  
A. Elgsaeter ◽  
J. J. Lopez Cascales ◽  
J. Garcia de la Torre
Keyword(s):  
Shear Flow ◽  
Brownian Dynamics ◽  
Flow Birefringence ◽  
Polymer Chains ◽  
Steady Shear ◽  
Dynamics Simulation ◽  
Brownian Dynamics Simulation ◽  
Flexible Polymer ◽  
Steady Shear Flow

3-D reconstruction of molecular shape from microcrystal thin sections

1983 ◽  
Vol 41 ◽  
pp. 748-749
Author(s):  
S. Cusack ◽  
J.-C. Jésior
Keyword(s):  
Three Dimensional ◽  
Molecular Shape ◽  
Biological Molecules ◽  
Fourier Space ◽  
Single Particles ◽  
Thin Sections ◽  
Standard Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dimensional Reconstruction

Three-dimensional reconstruction techniques using electron microscopy have been principally developed for application to 2-D arrays (i.e. monolayers) of biological molecules and symmetrical single particles (e.g. helical viruses). However many biological molecules that crystallise form multilayered microcrystals which are unsuitable for study by either the standard methods of 3-D reconstruction or, because of their size, by X-ray crystallography. The grid sectioning technique enables a number of different projections of such microcrystals to be obtained in well defined directions (e.g. parallel to crystal axes) and poses the problem of how best these projections can be used to reconstruct the packing and shape of the molecules forming the microcrystal.Given sufficient projections there may be enough information to do a crystallographic reconstruction in Fourier space. We however have considered the situation where only a limited number of projections are available, as for example in the case of catalase platelets where three orthogonal and two diagonal projections have been obtained (Fig. 1).

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