Development of a Universal Extensional Rheometer for the Uniaxial Extension of Polymer Melts

1972 ◽  
Vol 16 (3) ◽  
pp. 405-420 ◽  
Author(s):  
Joachim Meissner
Keyword(s):  
Polymer Melts ◽  
Uniaxial Extension

Characterisation of an Industrial Polymer Melt Through Either Uniaxial Extension or Exponential Shear Data: An Application of the Pom-Pom Model

2003 ◽  
Vol 13 (1) ◽  
pp. 19-25 ◽  
Author(s):  
Suneel ◽  
Richard S. Graham ◽  
Tom C.B. McLeish
Keyword(s):  
Strain Hardening ◽  
Simple Shear ◽  
Linear Response ◽  
Polymer Melts ◽  
Molecular Model ◽  
Uniaxial Extension ◽  
Polymer Melt ◽  
Non Linear ◽  
Ldpe Melt ◽  
Made In

Abstract We present new non-linear data in extension and two different shear histories. These data are used to compare the effectiveness of using exponential shear data and uniaxial extension data to characterise the non-linear response of an industrial LDPE melt with the pom-pom molecular model. We conclude that extension and exponential shear both allow good predictions to be made in simple shear. However, the characterisation spectrum obtained from exponential shear data fails to predict the correct degree of strain hardening at low extension rates. From this study we are able to suggest circumstances under which exponential shear provides a useful characterisation of branched polymer melts.

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can stretch up to maximum length given by the maximum entropic drag-force from the arms, after which the star arms are withdrawn into the backbone tube.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.

Failure behavior after stepwise uniaxial extension of entangled polymer melts

2015 ◽  
Vol 59 (3) ◽  
pp. 751-767 ◽  
Author(s):  
Hao Sun ◽  
Panpan Lin ◽  
Gengxin Liu ◽  
Konstantinos Ntetsikas ◽  
Konstantinos Misichronis ◽  
...  
Keyword(s):  
Polymer Melts ◽  
Uniaxial Extension ◽  
Failure Behavior ◽  
Entangled Polymer ◽  
Entangled Polymer Melts

Elastic Breakup in Uniaxial Extension of Entangled Polymer Melts

2007 ◽  
Vol 99 (23) ◽  
Author(s):  
Yangyang Wang ◽  
Pouyan Boukany ◽  
Shi-Qing Wang ◽  
Xiaorong Wang
Keyword(s):  
Polymer Melts ◽  
Uniaxial Extension ◽  
Entangled Polymer ◽  
Entangled Polymer Melts

Breakdown of Time–Temperature Equivalence in Startup Uniaxial Extension of Entangled Polymer Melts

2013 ◽  
Vol 46 (10) ◽  
pp. 4151-4159 ◽  
Author(s):  
Hao Sun ◽  
Konstantinos Ntetsikas ◽  
Apostolos Avgeropoulos ◽  
Shi-Qing Wang
Keyword(s):  
Polymer Melts ◽  
Uniaxial Extension ◽  
Entangled Polymer ◽  
Entangled Polymer Melts

Basic characteristics of uniaxial extension rheology: Comparing monodisperse and bidisperse polymer melts

2011 ◽  
Vol 55 (6) ◽  
pp. 1247-1270 ◽  
Author(s):  
Yangyang Wang ◽  
Shiwang Cheng ◽  
Shi-Qing Wang
Keyword(s):  
Polymer Melts ◽  
Uniaxial Extension ◽  
Basic Characteristics
Sign in / Sign up

Export Citation Format

Share Document