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Pressure Quench of flow-induced crystallization Zhe Ma, Luigi Balzano, Gerrit W M Peters Materials Technology Department of Mechanical Engineering Eindhoven University of Technology Putting values to a model for Flow Induced Crystallization (DPI #714,VALFIC) Z. Ma, G.W.M. Peters Materials Technology Department of Mechanical Engineering Eindhoven University of Technology Slide 2 flow structures properties motivation Slide 3 [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 flow strength mild strong depending on the molecular mobility more point-like nuclei oriented nuclei quiescent (no flow) point-like nuclei, f(T) nuclei structure Slide 4 Limitation: precursors without electron density difference (or very little concentration) SAXS electron density difference Limitation: non-crystalline precursors WAXD crystalline structure How to observe nuclei: Small Angle X-ray Scattering (SAXS) Wide Angle X-ray Diffraction (WAXD) flow objective Slide 5 point-like nuclei oriented nuclei crystallization after flow formation during flow No row nuclei -- No shish nuclei Yes observable Slide 6 objective point-like nuclei oriented nuclei crystallization after flow (kinetics) No row nuclei -- No shish nuclei Yes observable Slide 7 coloredlarge nucleation density shear Microscopyno yes Dilatomeryyes no DSCyes no Rheometryyes objective develop a method which is (more) reliable, simple, also works with flow. Slide 8 suspension-based model [1] linear viscoelastic three dimensional generalized self-consistent method [2] Relative dynamic modulus, f* G =G*/G* 0 [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 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. measure G*(T) space filling nucleation density N(T) Avrami Equation ? Slide 9 method suitable for combined effect of NA and flow Z Ma et al. Rheol Acta (2011) DOI 10.1007/s00397-010-0506-1 suspension-based model iPP and U-Phthalocyanine (145 o C) Slide 10 objective point-like nuclei oriented nuclei crystallization after flow (orientation and kinetics) No row nuclei -- No shish nuclei Yes observable Slide 11 increase T equilibrium by pressure decrease T exp by fast cooling --- Temperature quench difficult for large devices Undercooling is expected to start crystallization --- Pressure quench! crystallization: 1. morphology (isotropic or oriented) 2. kinetics (compared with quiescent case) objective Slide 12 Pressure-quench Set-up Multi-Pass Rheometer (MPR) Protocol Erase history at 190 o C and cool to 134 o C A apparent wall shear rate: 60 1/s shear time: 0.8s 300bar reference 50bar Slide 13 50bar flow highly oriented crystals a c b row nuclei Pressure-quench Pressure Quench a c b twisted lamellae t=0st=17s Slide 14 Pressure-quench Set-up Multi-Pass Rheometer (MPR) Protocol Erase history at 190 o C and cool to 134 o C A apparent wall shear rate: 60 1/s shear time: 0.8s 300bar reference 50bar annealing after flow, t a =22min Slide 15 results 0s 8.5s 34s 93.5s annealing (t a =22min) Pressure Quench 0s 8.5s 17s 102s no annealing Slide 16 experimental theoretical (tube model) results relaxation of orientation Slide 17 experimental theoretical (tube model) For HMW tail (1,480,000 g/mol) at 134 o C results Long lifetime of orientation Besides molecular mobility, other effect exists. relaxation of orientation Slide 18 theoretical (tube model) For HMW tail (1,480,000 g/mol) at 134 o C results Long lifetime of orientation iPP [1] Besides molecular mobility, other effect exists. relaxation of orientation [1] H An et al. J. Phys. Chem. B 2008, 112, 12256 Slide 19 theoretical (tube model) For HMW tail (1,480,000 g/mol) at 134 o C results Long lifetime of orientation Interaction between PE chains (or segments) at 134 o C [1] H An et al. J. Phys. Chem. B 2008, 112, 12256 iPP [1] relaxation of orientation Slide 20 annealing (t a =22min)no annealing results average nuclei density specific (200) diffraction (equatorial, off-axis or meridional) randomization of c-axes content of twisting overgrowth (nuclei density) Slide 21 annealing (t a =22min)no annealing results average nuclei density lower nuclei density some nuclei relax within annealing specific (200) diffraction (equatorial, off-axis or meridional) randomization of c-axes content of twisting overgrowth (nuclei density) Slide 22 0s 8.5s 34s 93.5s results Pressure Quench with annealing (ta=22min) Using Pressure Quench, it is found that nuclei orientation survives but average nuclei density decreases within annealing. orientation kinetics apparent crystallinity Z Ma et al. to be submitted Slide 23 results flow field in the slit WAXD results after flow the whole sample in situ characterization the first formation outer layer (strongest flow) X-ray Slide 24 objective point-like nuclei oriented nuclei formation during flow No row nuclei -- No shish nuclei Yes observable Slide 25 combining rheology (Multi-pass Rheometer,MPR) and X-ray DUBBLE@ESRF Pilatus experimental to track shish formation during flow MPR (30 frame/s) Slide 26 X-ray (30 frame/s) DUBBLE@ESRF Pilatus experimental Pressure difference and shish during flow MPR flow time 0.25s combining rheology and X-ray Slide 27 rheology iPP (HD601CF) at 145 o C wall stress results For 240, pressure difference deviates from the steady state and shows an upturn. upturn Slide 28 rheology iPP (HD601CF) at 145 o C results iPP (PP-300/6) at 141 o C [1] [1] G Kumaraswamy et al Macromolecules 1999, 32, 7537 approach steady state after start-up of flow 0.03 MPa birefringence Slide 29 rheology iPP (HD601CF) at 145 o C results upturn iPP (PP-300/6) at 141 o C [1] [1] G Kumaraswamy et al Macromolecules 1999, 32, 7537 birefringence upturn [1] oriented precursors P upturn precursory objects form faster at higher shear rate 0.06 MPa Slide 30 flow P upturn precursors during flow. 1). formation of precursor apparent shear rate of 400s -1 and T = 145 o C time for precursor formation is around 0.1s results Slide 31 time 0.20s 0.23s 0.26s 0.40s 0.10s 2). from precursor to shish apparent shear rate of 400s -1 and T = 145 o C 2D SAXS shishstreak results flow stops at 0.25s Slide 32 flow SAXS results 2D SAXS flowshish SAXS equatorial Intensity shish formation around 0.23s 2). from precursor to shish apparent shear rate of 400s -1 and T = 145 o C Slide 33 flow rheological response flow SAXS P upturn around 0.1s results shish formation around 0.23s Precursors develop into shish apparent shear rate of 400s -1 and T = 145 o C Slide 34 t = 0.13s t = 0.17s t = 0.20s results shish Shish forms during flow, faster at 560s -1 than 400s -1. apparent shear rate of 560s -1 and T = 145 o C Slide 35 t = 0.26s t = 0.33s t = 0.37s results shish apparent shear rate of 320s -1 and T = 145 o C Shish precursors form during flow and shish forms after flow. Slide 36 results SAXS results linked to the FIC model Nucleation and growth model[1] [1] F. Custodio et al. Macromol. Theory Simul. 2009, 18, 469 growth rate number of nuclei length growth total length of shish Slide 37 conclusions point-like nuclei oriented nuclei No row nuclei -- No shish nuclei Yes observable Suspension-based model innovation Formation of row nuclei is visualized. Stable nuclei can survive within 22-min annealing. Unstable ones relax within 22-min annealing. Pressure Quench 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. The combined effect of nucleating agent and flow on the nucleation density can be assessed. conclusions Slide 38 Acknowledgements Prof. Gerrit Peters Dr. Luigi Balzano Ir. Tim van Erp Ir. Peter Roozemond Ir. Martin van Drongelen Dr. Giuseppe Portale Slide 39 Thank you for your attention