Micro-scale Polymer Processing: Multiscale Modelling of Entangled Polymers

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Micro-scale Polymer ProcessingMultiscale
Modelling of Entangled Polymers
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Polymer Processing in the 21st century?
Reaction Chemistry
Molecular shape
Melt Rheology
Good processing
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Industrial LCB and the Buffer Zone
INDUSTRIAL RESINS
THEORY
MODEL MATERIALS
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The Scaffold Concept
INDUSTRY
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The Principle

• Follow the processing path of well characterised
  polymers from synthesis through processing and
  property evaluation combined with the parallel
  development of a mathematical and computational
  protocol.

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The Team

• Leeds
• Tom McLeish, Oliver Harlen, David Groves, Alexei
  Likhtman, Tim Nicholson, Alan Duckett, John
  Embery, Jorge Ramirez, Chinmay Das, Harley Klein,
  Dietmar Auhl
• Bradford
• Phil Coates, Tim Gough, Mike Martyn, Rob Spares
• Durham
• Lian Hutchins, Nigel Clarke, Eduardo de Luca
• Sheffield
• Tony Ryan, Ellen Heeley, Patrick Fairclough, Ron
  Young, Christine Fernyhough
• Cambridge
• Malcolm Mackley, Karen Lee, Ashish Lele, Mark
  Collis, David Hassell
• Oxford
• Paul Buckley, Junjie Wu, David de Foccatis

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Outline
Compression Craze Birefringence
Ox ford Model
Cambridge MPR4/ Bradford-Durham recirc.
flowSolve
Durham SANS Sheffield SAXS
G, shear transients, step shear Mei?ner
extensional
Tube models LCB Pom-Pom linear ROLIEPOLY
hPSdPS linears 3 blends PB combs PB linears
hPB variants
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Synthesis Platform

• Make polybutadiene in controlled fashion

• Polydispersity lt 1.05
• Molecular weight determined by reagent quantities
• Micro-structure affected by temperature, solvent
• Then hydrogenate to make polyethylene

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Molecular Theory Platform
Update on tube model physics Reptation Contour
Length Fluctuation Constraint Release
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Detailed Chain Formulation
Graham, Likhtman, Milner, TCBM
Reptation CLF
flow
CR
retraction
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Linear shear rheology andpredictions
µPP2 software tool RepTate
Lines are predictions from linear theory
(Likhtman McLeish 2002)
Tref. 25 C
Model Parameters from linear theory (Likhtman
McLeish 2002) ?e (25C) 0.003 s Ge (25C)
0.569 MPa Me 4.86 kg/mol cv 0.1
PI-4k
PI-14k
PI-30k
PI-90k
PI-200k
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Flow solving Platform

• Constitutive equation can be used to calculate
  polymer stress.
• Develop a Lagrangian finite element flow solver
  whose moving triangular grid elements can hold
  the constitutive parameters (orientation and
  stretch for each mode).

• Solve momentum and mass conservation
  equationswhere ? is the polymeric stress

Nicholson, Bishko, Harlen
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flowSolve output planar flow

• The recirculating vortex in the corner grows
  considerably as the simulation proceeds.
• The maximum stretch is not along the centre line,
  but lies between the centre line and the
  recirculating region where the material is
  sheared prior to extension.

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MuPP2 Structure
A Matrix approach to Industrial demand and
technical opportunity
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MuPP2 Management

• Special task groups
• Rheology team
• Synthesis team
• Solid State team
• Flow solving software team
• PDRA conference

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2PHASE Mesoscale Simulations
Two-dimensional simulations of freely suspended
particles in a polymeric fluid under shear
flow. Biperiodic lattice to extend a unit cell
containing N particles to an infinte domain.

• Under shear these cells slide
• relative to one another.

O. Harlen and A. Malidi
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CRYSTAL
Shear-induced crystallization of comb 10
sheared at 100 s-1 for 5 s prior to
crystallisation
54 kg mol-1 backbone with 8 arms of 15 kg mol-1
No shear

• Massively increased rates after shear
• Well oriented crystals (no shearing during
  crystallisation)

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Conclusions

• Model materials refine new entanglement physics
• Molecular structure has flow-field consequences
• Chain orientation is a family of numbers
• Routes to Polydisperse architectures
• Methodology extends to product structure in phase
  and crystallinity.