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PROBING POLYMER CRYSTALLIZATION IN PROCESSING CONDITIONS (using synchrotron radiation)

Synchrotron Radiation in Polymer Science 5 San Francisco, 30 th March – 2 nd April 2012. PROBING POLYMER CRYSTALLIZATION IN PROCESSING CONDITIONS (using synchrotron radiation). D. Cavallo , L. Balzano, G. Portale, G.W.M. Peters, G.C. Alfonso.

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PROBING POLYMER CRYSTALLIZATION IN PROCESSING CONDITIONS (using synchrotron radiation)

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  1. Synchrotron Radiation in Polymer Science 5 San Francisco, 30th March – 2nd April 2012 PROBING POLYMER CRYSTALLIZATION IN PROCESSING CONDITIONS (using synchrotron radiation) D. Cavallo, L. Balzano, G. Portale, G.W.M. Peters, G.C. Alfonso

  2. Crystallization of polymers in “unperturbed” conditions Hierarchical organization Spherulites ~10-100 μm Chain folded lamellae ~10 nm Unit cell ~1-10 Å

  3. Crystallization of polymers in “unperturbed” conditions Crystallization kinetics Growth of PLLA spherulites, Optical Microscopy

  4. Polymer processing Combined application of: • HIGH COOLING RATES • ( 101-103 K/s ) • FLOW FIELDS • ( 10-1-103 s-1 )

  5. Crystallization of polymers in “real” conditions Injection molded sample Final structure depends on local thermo-mechanical history

  6. Outline • Crystallization under fast cooling conditions “Model” experiments • Effect of flow on crystallization • Structure formation during real processing

  7. Fast cooling: Continuous-Cooling-Transformation diagrams Very important for steel technology, (almost) neglected for semicrystalline polymers

  8. Experimental method Quenching device cooling rate up to ≈200°C/s Acq. time 0.05 s DUBBLE@ESRF, March 2010

  9. Case 1: Polymorphism of quenched isotactic polypropylene Q. Zia et al. Polym. Bull. 2008, 60, 791 D. Mileva, et al. Polymer 2009, 50, 5482

  10. An actual experiment

  11. Continuous-Cooling-Transformation diagram of i-PP Prevailing alpha phase Mixed structure Prevailing mesophase

  12. Effect of comonomer on CCT diagrams

  13. Effect of comonomer on CCT diagrams

  14. Case 2: Polymorphism of quenched polyamide 6 a-phase • monoclinic • themodynamically stable • sheet-like hidrogen bonding mesophase • pseudo-hexagonal • metastable • irregular hidrogen bonding

  15. Continuous – Cooling –Transformation diagrams of PA6 PA6 18kDa a-phase mesophase amorphous

  16. Flow induced crystallization: consequences

  17. Flow induced crystallization: causes nucleating effect on crystallization melt FLOW dissolution of flow induced structures cluster of (locally) oriented chain segments

  18. Flow induced crystallization: experimental methods X-ray diamond windows Pilatus (30 frame/s) Multi-pass rheometer @ DUBBLE, ESRF

  19. Flow induced crystallization: experimental methods Rotational shearing device Linkam CSS 450 coupled with SAXS at Beamline A2 HASYLAB/DESY

  20. What happens during flow SAXS WAXD time Crystallization onset time in flow ̴ 10-1s 0.13s 0.17s (110) Quiescient onset time ̴ 103s shish 0.20s (110) FLOW STOPS 0.27s (110) (130) (040) i-PP, “apparent” shear rate of 560s-1; T = 145 °C

  21. Effect of flow induced structures on rheology Rheology iPP, T = 145 °C DP = P bottom - P top  wall stress Huge increase in viscosity during shear: “suspension” of shishes

  22. Dissolution of shear-induced nucleation precursors: indirect evidences Relaxation effect on crystal orientation Relaxation effect on crystallization kinetics

  23. Dissolution of shear-induced nucleation precursors: mechanism Relaxation temperature increases Rate controlling step: detachment of segments from the surface of oriented clusters

  24. Crystallization during real processing : in-situ study of film blowing Take-up direction 2D WAXD detector (fixed position) X-ray beam (fixed height) Die exit

  25. Crystallization during real processing : in-situ study of film blowing Take-up direction 2D WAXD detector (fixed position) X-ray beam (fixed height) Die exit

  26. Film blowing at synchrotron facilities : experimental setup Collin Blown Film Unit type 180 Die-extruder on a manually operated hydraulic lifter

  27. Film blowing at synchrotron facilities : experimental setup

  28. Data analysis: WAXD patterns vs. axial position c b a

  29. Results BUR= final bubble diameter/bubble diameter at the die TUR= take-up velcoity/velocity at the die exit

  30. Bubble kinematics Video tracker technique Velocity profiles Machine direction

  31. “Corrected” results Elongation in both machine and transverse direction affects crystallization kinetics

  32. Acknowledgments (this work would not have been possible without...) Daniel Hermida-Merino, BM26/DUBBLE - ESRF, Grenoble (France) Florian Ledrappier, BM26/DUBBLE - ESRF, Grenoble (France) Wim Bras, BM26/DUBBLE - ESRF, Grenoble (France) Sergio Funari, A2 - HASYLAB, DESY (Germany) Daniela Mileva, University of Halle (Germany) Renè Androsch, University of Halle (Germany) Zhe Ma, Eindhoven University of Technology (The Netherlands) Roberto Floris , University of Genova (Italy) Lorenza Gardella, University of Genova (Italy)

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