Molecular Observation of Branch Point Motion in Star Polymer Melts

2010 ◽  
Vol 43 (1) ◽  
pp. 518-524 ◽  
Author(s):  
Michaela Zamponi ◽  
Wim Pyckhout-Hintzen ◽  
Andreas Wischnewski ◽  
Michael Monkenbusch ◽  
Lutz Willner ◽  
...  
Keyword(s):  
Branch Point ◽  
Polymer Melts ◽  
Star Polymer ◽  
Point Motion

Branch-Point Motion in Asymmetric Star Polymers

2005 ◽  
Vol 38 (10) ◽  
pp. 4484-4494 ◽  
Author(s):  
Jung Hun Lee ◽  
Lewis J. Fetters ◽  
Lynden A. Archer
Keyword(s):  
Branch Point ◽  
Star Polymers ◽  
Point Motion

Surface Tension of Symmetric Star Polymer Melts

2008 ◽  
Vol 41 (13) ◽  
pp. 5007-5013 ◽  
Author(s):  
Zhenyu Qian ◽  
Venkatachala S. Minnikanti ◽  
Bryan B. Sauer ◽  
Gregory T. Dee ◽  
Lynden A. Archer
Keyword(s):  
Surface Tension ◽  
Polymer Melts ◽  
Star Polymer ◽  
Symmetric Star

Arm-Length Dependence of Stress Relaxation in Star Polymer Melts

1998 ◽  
Vol 31 (21) ◽  
pp. 7479-7482 ◽  
Author(s):  
S. T. Milner ◽  
T. C. B. McLeish
Keyword(s):  
Stress Relaxation ◽  
Polymer Melts ◽  
Star Polymer ◽  
Length Dependence

The Molecular Rheology of Star Polymer Melts: Binary Blends

1998 ◽  
pp. 324-325
Author(s):  
B. Blottière ◽  
T. C. B. McLeish ◽  
A. Hakiki ◽  
R. N. Young ◽  
S. T. Milner
Keyword(s):  
Polymer Melts ◽  
Star Polymer ◽  
Binary Blends

Molecular Drag-Strain Coupling in Branched Polymer Melts

2000 ◽  
Vol 629 ◽  
Author(s):  
Richard J. Blackwell ◽  
Tom C. B. McLeish ◽  
Oliver G. Harlen
Keyword(s):  
Branch Point ◽  
Polymer Melts ◽  
Uniaxial Extension ◽  
Extensional Viscosity ◽  
Low Density Polyethylene ◽  
Model Parameters ◽  
Low Density ◽  
Branch Points ◽  
Nonlinear Rheology ◽  
Branched Polymer

ABSTRACTThe “pom-pom” model of McLeish and Larson (J. Rheol. 42, 81, 1998) provides a simple molecular theory for the nonlinear rheology of long chain branched polymer melts. The Edwards-de Gennes tube concept is used to derive a constitutive equation for a simple branched molecule composed of two star polymers linked by a single backbone chain. A feature of this model is that the backbone section of tube can stretch up to maximum length given by the maximum entropic drag-force from the arms, after which the star arms are withdrawn into the backbone tube. This produces a sharp transition in the extensional viscosity at this maximum stretch. This unphysical feature results from an over-simplification of the behaviour near the branch points.In this paper we introduce a simple treatment of the coupling between relaxed and unrelaxed polymer segments at branch-points. This allows for localised displacements of branch-point within a quadratic potential before maximum extension is reached. Displacing the branch-point reduces the length of arm outside the tube and so reduces in the drag on the star arms. This smoothes out the sharp transitions in extensional viscosity in the original “pom-pom” model at the cost of introducing an extra unknown parameter.This modification improves the prediction of the nonlinear rheology of H-polymers whose molecular structure is known. Alternatively, for polymers of unknown structure such as commercial Low Density Polyethylene, the model parameters may be fitted from linear viscoelastic and uniaxial extension data, to provide predictions for the behaviour in transient nonlinear shear and planar extension. By including local branch-point displacement we find improved agreement with the data for Low-Density Polyethylene.

Coarse grain forces in star polymer melts

Soft Matter ◽  
2014 ◽  
Vol 10 (39) ◽  
pp. 7874-7886 ◽  
Author(s):  
L. Liu ◽  
W. K. den Otter ◽  
W. J. Briels
Keyword(s):  
Single Particle ◽  
Polymer Melts ◽  
Relaxation Modulus ◽  
Star Polymers ◽  
Star Polymer ◽  
Coarse Grain ◽  
Particle Model ◽  
Single Particle Model ◽  
Shear Relaxation ◽  
Transient Force

Shear relaxation modulus for star polymers (3 arms, 35 beads each) reproduced by single particle model including transient force.

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