Precise Polymer Processing

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Precise Polymer Processing BY MALCOLM
MACKLEY. POLYMER FLUIDS GROUP. DEPARTMENT OF
CHEMICAL ENGINEERING. UNIVERSITY OF
CAMBRIDGE. UK. mrm5_at_cam.ac.uk
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Background

• MPR1, commissioned in 1995
• Microscale Polymer Processing initiative, 2000
  onwards
• Cross slot development
• Ability to rank numerical simulation against
  experiment for small quantities of polymer.

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The Multipass Rheometer (MPR)
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MPR4
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Key issues for Processing
in general Temperature Pressure
Flow Time
Key features of MPR
Temperature -10 to 210
Centigrade Pressure 1 to 200
bar Flow 1 to
10000 reciprocal seconds Time
ms to hours Enclosed small volume 20g
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J Rheology 1995 Multipass steady mode.
Silicon oil
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J Rheology 1995 Pressure dependant viscosity
silicon oil
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J Rheology 1995 Linear viscoelastic response
Polymer solution
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J Rheology 1995 Frequency response Polymer
solution
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Steady Shear Response
MPR flow curves polymer melts
apparent viscosity vs shear rate polydisperse
polystyrene
PS680E at 200C
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Polyethylene extrusion
A multi-pass steady-mode time profile of the
axial pressure difference and piston position
(piston speed 8.5 mms-1 piston amplitude
5.5 mm and idle time 3 seconds). The data was
obtained for a LLDPE at a temperature of 190oC
using a capillary of (L/a40/2).
Karen Lee 2001
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3. Processing vs Simulation
Simulations used Polyflow Flowsolve In
conjunction with Prof Tom Mcleish Leeds
UK Rudyflow In conjunction with Dr Rudy Valette
CEMEF Sophia Antipolis France.
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InSitu flow birefringence of polymer melts
Special optical cell as a central test
section Possibility to use polarised light for
visualisation of stresses by birefringence
1970s Han Drexler 1980s Wales
Mackley Meijer Agassant

Issues. 2D flow, Stress optical coefficient.
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David Hassell
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Flow
David Hassell 2006
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Molecular Constitutive Equations Multi mode-Pom
Pom and Rolie Poly
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Time 0.06 s
Time 2.76 s
Time 2.85 s
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Pressure profiles
Rudy Valette
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Pressure relaxation
Differential Pressure bars
compressible Carreau ( - - - ), incompressible
Rolie Poly ( ) and compressible Rolie Poly (
).
Rudy Valette
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Absolute Pressure Prediction.
compressible Carreau ( - - - ), incompressible
Rolie Poly ( ) and compressible Rolie Poly (
).
Absolute Pressure bars
Time
Rudy Valette
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4. Extensional Flow
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The Cross Slot Geometry
Follow Eindhoven Group
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Cross-Slot in the MPR
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Apparatus Centre Section
Heating Oil Line
Quartz Window
Nitrogen Connection Flange
Cross-slot insert
Nitrogen line
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Cross Slot- Lightly branched HDPE
David Hassell
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Cross-Slot Stress build up
t time after beginning of flow
t 0s
t 0.26s
Black image no stress
Symmetric profile
Formation of cusps
Elongation of centreline fringes
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Cross-Slot steady state
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Simulation comparison Stress build up

• Lightly long chain branched PE

t time after beginning of flow

• Captures pattern of stress development,
• Over predicts the stress

POM-POM, q 1 and tb / ts 2 for all ?i modes
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Crystallisation
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David Hassell. slit crystallisation 2006
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David Hassell Cross Slot crystallisation 2006
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Relaxation spectrum?i contribution to zero
shear viscosity