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Hong Kong MPR -09

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This presentation reviews how it is now possible to model the processing flow of molten polymer

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Hong Kong MPR -09

  1. 1. Hong Kong 2009The experimental validation of numerical simulation for precise polymer melt processing by Malcolm Mackley, David Hassell* Tim Lord and Lino Scelsi. Department of Chemical Engineering and Biotechnology. University of Cambridge. UK *School of Chemical and Environmental Engineering. University of Nottingham. Selanger, Darul Ehsan, Malaysia 1
  2. 2. Mission• Carry out precise polymer processing experiments that can be compared with simulation.• Characterise rheology of polymer and select constitutive equation.• Numerically simulate viscoelastic flow and match result with experiment. 2
  3. 3. The Cambridge Multipass Rheometer (MPR)Rheo Optic slit flow mode Cross-slot flow mode 3
  4. 4. The Cambridge Multipass Rheometer (MPR) Top section Test section Bottom section 4
  5. 5. Test section geometries • Slit • Cross-Slot 0.75 mm1.5 mm 1.5 mm 10 mm Depth =10, 7 and 1.5 mm 1.5 mm 1.4 mm 5
  6. 6. The Geometries: Contraction Expansion Slit Depth =10, 7, and 1.5 mm 10 mm R = 0.375 mm Z ~ 1.4 mm 6
  7. 7. An example of Rheo optic slit flow for LDPE 7
  8. 8. Visit MPR Slit Flow movie 8
  9. 9. The Cross-Slot• Generates a hyperbolic pure shear flow pattern as shown.• Near centre. Essentially uniform extensional flow with residence time, which is equivalent to strain, inversely dependant on distance from the exit symmetry axis 9
  10. 10. MPR Cross-Slot Flow • The MPR action modified for cross-slot flow • Pistons force polymer melt through a cross- slot geometryKris Coventry and Collaborative project with Leeds University;Tom Mcleish et al 10
  11. 11. Typical Result-Dow PS680E-Piston velocity of 0.5mm/s (maximumextension rate =4.3/s).-Inlet slitwidth=1.5mm-Section depth=10mm- T=180°C. 11
  12. 12. Visit MPR Cross Slot Flow movie 12
  13. 13. Rheology and Characterisation• Linear viscoelasticity Obtain spectrum of relaxation times• Non Linear response. Sentmanat Extensional Rheometry fixtures (SER)• Constitutive equations Pom Pom or Rolie Poly• Simulation Leeds 2D Flowsolve or 3D EUsolve 13
  14. 14. SimulationFor linear polymer melts, “Rolie-Poly” theory is usedConstitutive equation; 14
  15. 15. Multimode Pom-Pom modelViscoelastic stress:Backbone orientation:Stretch:Time scales: 15
  16. 16. Vp = 0.44 mms-12D FlowsolveAnd3D EUsolvePolystyrene (PS2)10mm depthPom Pom 2D simulation 3D simulation dP = 3.32 bar dP = 3.76 bar 16
  17. 17. Vp = 0.44 mms-13D EUsolvePolystyrene (PS2)10mm depthLHS Pom PomRHS Experiment 3D simulation Experiment dP = 3.76 bar 17dP = 3.96 bar
  18. 18. Vp = 0.44 mms-13D EUsolvePolystyrene (PS2)7 mm depthLHS Pom PomRHS Experiment 3D simulation Experiment dP = 5.46 bar18 dP = 5.18 bar
  19. 19. Vp = 0.07 mms-13D EUsolvePolystyrene (PS2)1.5 mm depthLHS Pom PomRHS Experiment 3D simulation Experiment dP=17.24bar dP=9.66bar 19
  20. 20. Pom Pom vs Rolie Poly, 3D EUsolvePomPom t= 0.1 s t= 10 s t= 18.9 sRoliePoly t=8s 20 t = 12 s t = 0.1 s
  21. 21. Cross Slot Pom Pom 3D EUsolve Vp = 0.04 mms-1 Vp = 0.09 mms-13D simulation MPR experiment 3D simulation MPR experiment 21
  22. 22. Cross Slot 1.5mm depth. Pom Pom 3D EUsolve Vp = 0.07 mms Simulation Experiment 22
  23. 23. Cross Slot Pom Pom vs Rolie poly 3D EUsolvePomPom t = .1 s t = 8.5 s t = 37 sRoliePoly t = 0.1 s t =17 s t =37 s 23
  24. 24. Tim Lord, David Hassell and Dietmar Auhl 2008EPSRC Microscale Polymer Processing project 24
  25. 25. Stagnation Point flows as rheometers Dr Dietmar Auhl et al, Leeds University 2008 6elongational viscosityµ(t), Pas 10 0.3 . -1 1 0.1 0.03 0.01 ε0 [s ] shear viscosity η(t), Pas 3 0.003 10 0.001 5 10 . -1 γ0 [s ] 0.001 0.01 0.1 4 0.5 10 1 2 5 LDPE T = 150°C 10 3 10 -1 0 1 2 3 10 10 10 10 10 time t, s 25
  26. 26. η E ,st (ε) = (σ xx − σ yy ) st / εst steady-state elongational viscosity at the stagnation point 0 ε  = principle ε  0 ∆ n = SOC (σX xx − σ yy ) + 4σ xy • 2 2 ε st = A x V piston -4 -2 0 2 4 26
  27. 27. Dr Dietmar Auhl et al , Leeds University 27
  28. 28. Conclusions• MPR experiments provide precise processing data.• Both Rolie Poly and Pom Pom models can be simulated to give good experimental matching.• Simulation can be sensitive to both constitutive equations, relaxation spectra and non linear fit. Acknowledgements. Tom Mcleish for masterminding Microscale Polymer Processing project and EPSRC for providing most of the funds 28

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