1 / 39

Pressure Quench of flow-induced crystallization

Putting values to a model for Flow Induced Crystallization (DPI #714,VALFIC). Pressure Quench of flow-induced crystallization. Zhe Ma, Luigi Balzano, G errit W M Peters Materials Technology Department of Mechanical Engineering Eindhoven University of Technology. Z. Ma, G.W.M. Peters

adelio
Download Presentation

Pressure Quench of flow-induced crystallization

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Putting values to a model for Flow Induced Crystallization (DPI #714,VALFIC) Pressure Quench of flow-induced crystallization Zhe Ma, Luigi Balzano, Gerrit WM Peters Materials Technology Department of Mechanical Engineering Eindhoven University of Technology • Z. Ma, G.W.M. Peters • Materials Technology • Department of Mechanical Engineering • Eindhoven University of Technology

  2. motivation flow structures properties

  3. motivation structure flow strength depending on the molecular mobility strong mild quiescent (no flow) oriented nuclei point-like nuclei, f(T) more point-like nuclei nuclei [1] Swartjes F.H.M (2001) PhD thesis, Eindhoven University of Technology, NL [2] Hsiao B.S et al. (2005) Physical Review Letter, 94, 117802

  4. objective How to observe nuclei: Small Angle X-ray Scattering (SAXS) Wide Angle X-ray Diffraction (WAXD) …… flow SAXS electron density difference Limitation: precursors without electron density difference (or very little concentration) WAXD  crystalline structure Limitation: non-crystalline precursors

  5. objective observable point-like nuclei No crystallization after flow row nuclei -- No oriented nuclei formation during flow shish nuclei – Yes

  6. objective observable point-like nuclei crystallization after flow (kinetics) No row nuclei -- No oriented nuclei shish nuclei – Yes

  7. objective develop a method which is (more) reliable, simple, also works with flow.

  8. suspension-based model[1] ? space fillingf nucleation density N(T) measure G*(T) Avrami Equation linear viscoelastic three dimensional generalized self-consistent method[2] Relative dynamic modulus,f*G=G*/G*0 A*, B* and C*determined by ratio of the complex moduli of the continuous phase and dispersed phase, Poisson ratio of both phases: all known, A*, B* and C* then depend on space filling only. [1] R.J.A. Steenbakkers et al. Rheol Acta (2008) 47:643 [2] R.M. Christensen et al. J.Mech.Phys.Solids (1979) 27:315

  9. suspension-based model iPP and U-Phthalocyanine(145oC) method suitable for combined effect of NA and flow Z Ma et al. Rheol Acta (2011) DOI 10.1007/s00397-010-0506-1

  10. objective observable point-like nuclei No crystallization after flow (orientation and kinetics) row nuclei -- No oriented nuclei shish nuclei – Yes

  11. objective crystallization: 1. morphology (isotropic or oriented) 2. kinetics (compared with quiescent case) Undercooling is expected to start crystallization decrease Texp by fast cooling --- Temperature quench difficult for large devices increase Tequilibrium by pressure --- Pressure quench!

  12. Pressure-quench Set-up Multi-Pass Rheometer (MPR) Protocol Erase history at 190oC and cool to 134oC A apparent wall shear rate: 60 1/s shear time: 0.8s 300bar reference 50bar

  13. c b 50bar a c a b Pressure-quench Pressure Quench t=0s t=17s flow highly oriented crystals twisted lamellae row nuclei

  14. Pressure-quench Set-up Multi-Pass Rheometer (MPR) Protocol Erase history at 190oC and cool to 134oC A apparent wall shear rate: 60 1/s shear time: 0.8s 300bar reference 50bar annealing after flow, ta=22min

  15. no annealing 0s 8.5s 17s 102s annealing (ta=22min) 0s 8.5s 34s 93.5s results Pressure Quench

  16. results relaxation of orientation experimental theoretical (tube model)

  17. results relaxation of orientation experimental theoretical (tube model) For HMW tail (1,480,000 g/mol) at 134 oC Long lifetime of orientation Besides molecular mobility, other effect exists.

  18. results relaxation of orientation theoretical (tube model) For HMW tail (1,480,000 g/mol) at 134 oC iPP[1] Long lifetime of orientation Besides molecular mobility, other effect exists. [1] H An et al. J. Phys. Chem. B 2008, 112, 12256

  19. results relaxation of orientation theoretical (tube model) For HMW tail (1,480,000 g/mol) at 134 oC iPP[1] Long lifetime of orientation Interaction between PE chains (or segments) at 134oC [1] H An et al. J. Phys. Chem. B 2008, 112, 12256

  20. results average nuclei density specific (200) diffraction (equatorial, off-axis or meridional) no annealing annealing (ta=22min) randomization of c-axes content of twisting overgrowth (nuclei density)

  21. results average nuclei density specific (200) diffraction (equatorial, off-axis or meridional) no annealing annealing (ta=22min) randomization of c-axes content of twisting overgrowth (nuclei density) some nuclei relax within annealing lower nuclei density

  22. results Pressure Quench with annealing (ta=22min) orientation 0s 8.5s 34s 93.5s kinetics – apparent crystallinity Using Pressure Quench, it is found that nuclei orientation survives but average nuclei density decreases within annealing. Z Ma et al. to be submitted

  23. results flow field in the slit X-ray WAXD results after flow the whole sample in situ characterization  the first formation outer layer (strongest flow)

  24. objective observable point-like nuclei No row nuclei -- No oriented nuclei formation during flow shish nuclei – Yes

  25. experimental combining rheology (Multi-pass Rheometer ,MPR) and X-ray Pilatus MPR DUBBLE@ESRF (30 frame/s) to track shish formation during flow

  26. experimental combining rheology and X-ray X-ray Pilatus MPR DUBBLE@ESRF flow time 0.25s (30 frame/s) Pressure difference and shish during flow

  27. For ≥ 240 , pressure difference deviates from the steady state and shows an “upturn”. results rheology “upturn”  wall stress iPP (HD601CF) at 145oC

  28. results rheology birefringence 0.03 MPa iPP (PP-300/6) at 141oC[1] iPP (HD601CF) at 145oC approach steady state after start-up of flow [1]G Kumaraswamy et al Macromolecules 1999, 32, 7537

  29. results rheology birefringence “upturn”[1] “upturn” 0.06 MPa  oriented precursors iPP (PP-300/6) at 141oC[1] iPP (HD601CF) at 145oC ∆P “upturn”  precursory objects form faster at higher shear rate [1]G Kumaraswamy et al Macromolecules 1999, 32, 7537

  30. results apparent shear rate of 400s-1 and T = 145oC 1). formation of precursor flow ∆P “upturn”  precursors during flow. time for precursor formation is around 0.1s

  31. shish streak results apparent shear rate of 400s-1 and T = 145oC 2). from precursor to shish 2D SAXS time 0.10s 0.20s 0.23s flow stops at 0.25s 0.26s 0.40s

  32. results apparent shear rate of 400s-1 and T = 145oC 2). from precursor to shish SAXS 2D SAXS flow flow shish SAXS equatorial Intensity shish formation around 0.23s

  33. results apparent shear rate of 400s-1 and T = 145oC rheological response SAXS flow flow shish formation around 0.23s ∆P “upturn” around 0.1s Precursors develop into shish

  34. results apparent shear rate of 560s-1 and T = 145oC t = 0.13s t = 0.17s shish t = 0.20s Shish forms during flow, faster at 560s-1 than 400s-1.

  35. results apparent shear rate of 320s-1 and T = 145oC t = 0.26s t = 0.33s shish t = 0.37s Shish precursors form during flow and shish forms after flow.

  36. results SAXS results linked to the FIC model Nucleation and growth model[1] growth rate number of nuclei length growth total length of shish [1] F. Custodio et al. Macromol. Theory Simul. 2009, 18, 469

  37. conclusions conclusions innovation observable point-like nuclei Suspension-based model • The combined effect of nucleating agent and flow on the nucleation density can be assessed. No Pressure Quench • Formation of row nuclei is visualized. • Stable nuclei can survive within 22-min annealing. • Unstable ones relax within 22-min annealing. row nuclei -- No oriented nuclei Combining rheology and synchrotron X-ray • Shish formation is tracked during flow. • The shish precursors are formed during flow and further develop into shish. • Formation times of shish precursors and shish both depend on the flow conditions. shish nuclei – Yes

  38. Acknowledgements Prof. Gerrit Peters Dr. Luigi Balzano Ir. Tim van Erp Ir. Peter Roozemond Ir. Martin van Drongelen Dr. Giuseppe Portale

  39. Thank you for your attention

More Related