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mrm Chamonix-stretching chains-(2009)

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Malcolm Mackley "Polymer chain Stretching" presentation. Chamonix (2009). GFR deGennes discussion meeting

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mrm Chamonix-stretching chains-(2009)

  1. 1. Chamonix France Feb 2009 Pierre de Gennes Research Meeting Stretching Polymer Chains by Malcolm Mackley With acknowledgement to The Late Sir Charles Frank, Sir Michael Berry, The late Andrew Keller. Dr Kris Coventry, Dr Tim Lord, Lino SelsciDepartment of Chemical Engineering and Biotechnology University of Cambridge 1
  2. 2. Time line• Pre 1970 Background “a bit of History” Tom Mcleish•1970s Stagnation point flows A slight digression “ Catastrophe” “Our financial friends” Armand Ajdari•1980s Real chain stretch “ we don’t understand entanglements” Ralph Colby• 2005 Stagnation point flows; the Cross Slot 2 “use the inventions of others” Armand Ajdari
  3. 3. The stretching of liquid droplets G.I.Taylor 1934 Four roll mill Parallel Band Ca ≥ 1 Summarised by “The Grace diagram” Simple shearCapillarynumber η γDCa = c 1 pure shear ν 1 Viscosity ratio of drop to matrix Capillary number criteria for drop deformation Ca ≥ 1 3
  4. 4. The stretching of Polymer; Chains Peterlin and Ziabicki 1960s Kinetic TheoryPolymer ofChain extension Kuhn and Kuhn 1940s β = γτ  γ = strain rate, τ = chain relaxation time of polymer chain  Β number criteria for polymer chain extension β = γ τ ≥ 1 4
  5. 5. Pioneers in Science 1970sCharles Frank Andrew Keller Pierre de GennesScience Science ScienceGeometry Crystallisation Scaling 5
  6. 6. Albert Pennings; Groningen 1970 6
  7. 7. Polyethylene Diamond 7
  8. 8. 1969Sir Charles Frank Opposed jets B number criteria for chain extension β = γ τ ≥ 1 8
  9. 9. Chain extension with opposed jetsB number criteria for chain extension β = γ τ ≥ 1 9
  10. 10. Localized Flow Birefringence of Polyethylene Oxide Solutions in a Four Roll Mill 1974 Crowley et al. Journal of Polymer Science: Vol 14 1111-1119 (1976) 10
  11. 11. B number criteria for chain extension β = γ τ ≥ 1 Strain criteria for chain extension γ t ≥ γ 0 11
  12. 12. The Two Roll Mill 1974Confirms localisation in extensional flows 12
  13. 13. A short digression.Christopher Zeeman; University of Warwick 1970s 13
  14. 14. Rene Thom; Catastrophe Theory!(Something our financiers and politicians should have studied !) 14
  15. 15. Catastrophe Theory The teaching of Christopher Zeeman! “dogs (or birds) ” meetingFriendly Control Parameter; 1 / distance apartAggressive 15
  16. 16. Catastrophe Theory The economyGreed Control Parameter; TimeContentment Margaret Thatcher Tony Blair Gordan Brown 16
  17. 17. Catastrophe Theory; The Six Roll Mill 1976M.V.Berry and M.R. Mackley. Phil. Trans. Roy. Soc. Lond. 287, 1337, 1-16 (1977). 17
  18. 18. 18
  19. 19. Stream function for Six Roll Mill flow pattern 1 3 2 1φ (x, y) = γ ( x - x y ) - ω ( x 2 + y 2 ) - Vy x + Vx y 3 2 dφ dφ Vx = , Vy = - dy dx 19
  20. 20. The elliptic umbilic Berry and Mackley 20 Bristol 1976
  21. 21. Berry and Mackley 1976 21
  22. 22. The elliptic umbilic Berry and Mackley 22 Bristol 1976
  23. 23. 1980s Back to stretching chains!Shish KebabCore;Extended chainExpectE=100 GPaNot usualE=1 GPa 23
  24. 24. Paul Smith. Piet LemstraNow ETH Now TU Eindhoven 24
  25. 25. UHMWPE gel processing Piston 1. Low entanglement UHMWPE polymer gel Solvent recovery2. Unoriented Gel fibre 4. Hot draw Quench bath 5. Oriented High Modulus Polyethylene 3. Unoriented Low entanglement semi crystalline fibre Schematic diagram of High Modulus Polyethylene (HMP) process P. Smith, and P.J.Lemstra, J. Material. Sci. 1980, 15, 505 25
  26. 26. Continuous processing of UHMWPE Dyneema Solvent r UHM WPE Polymer powde Low entanglement polymer gel Screw extrude rSpinneret Solvent recovery Gel fibres Hot draw Quench bath Low entanglement semi crystalline fibre Schematic diagram of continuous High M odulus Polyethylene (HM P) process 26
  27. 27. 2000Whitstable UK 27
  28. 28. 2005 Back to stagnation point flows The Cross-Slot• Generate a hyperbolic pure shear flow pattern as shown.• Near the walls the flow deviates from ideal.• Along the symmetry axes rotation free pure extensional flow. 28
  29. 29. The MultiPass Rheometer, (MPR) 1995 MPR for Cross-Slot Flow 2005• The MPR action modified for cross-slot flow• Pistons force polymer melt through a cross-slot geometry Kris Coventry and Collaborative project with Leeds University; Tom Mcleish et al 29
  30. 30. Apparatus Servo-hydraulically• Molten polymer is driven piston driven through test section by two servo- hydraulic pistons. 0.75 mm 1.5 mm radius• Air pressure is used to Slave piston driven by air Slave piston return polymer so that pressure driven by air pressure multiple experiments 1.5 mm can be carried out. Servo-hydraulically driven piston 30
  31. 31. Apparatus 31
  32. 32. Centre Section 3 cm 32
  33. 33. Cross Section of Apparatus Hot oil supply Camera lens Beam Focus AnalyserLight Source and Polarisermonochromatic P, T Transducers Nitrogen supply (for cross-slot flow only) 33
  34. 34. 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. 34
  35. 35. Newtonian Simulation PolyflowNewtonianConstitutiveEquation:Viscosity =7000 Pa.s 35
  36. 36. Power Law Simulation PolyflowPower LawConstitutiveEquation:EffectiveViscosity =7000*(0.3*γ)^ 0.75 Pa.s 36
  37. 37. Integral Wagner Simulation Polyflow- Integral WagnerConstitutiveEquation- 8 moderelaxationspectrum.- Single dampingcoefficient 37
  38. 38. Reptation based Pom-Pom Simulation Flowsolve (Leeds)8 modePom-PomConstitutiveEquation. 38
  39. 39. Pom-Pom Simulation from Software by Rudy Valette-8 modePom-Pommodel.-AcknowledgeR. Valette(CEMEF) 39
  40. 40. Tim Lord, David Hassell and Dietmar Auhl 2008EPSRC Microscale Polymer Processing project 40
  41. 41. Newtonian Mildly viscoelastic ViscoelasticViscoelastic solution melt 41
  42. 42. 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 42
  43. 43. 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 43
  44. 44. Dr Dietmar Auhl et al , Leeds University 44
  45. 45. So;Is the Frank, Keller, de Gennes era over ? 45
  46. 46. Yes. but, I hope others will followtheir inspirational example. 46

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