#### Transcript Hoe maak je een presentatie in de huisstijl van de TU/e?

Putting values to a model for Flow Pressure Quench of flow-induced Induced Crystallization crystallization (DPI #714,VALFIC) Z. PetersGerrit W M Peters ZheMa, Ma,G.W.M. Luigi Balzano, Materials MaterialsTechnology Technology Department Engineering DepartmentofofMechanical Mechanical Engineering Eindhoven of Technology EindhovenUniversity University of Technology motivation flow structures properties motivation structure depending on the molecular mobility quiescent mild flow strength strong (no flow) nuclei point-like nuclei, f(T) more point-like nuclei oriented 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 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 objective observable point-like No crystallization after flow nuclei row nuclei -- No oriented nuclei shish nuclei – Yes formation during flow objective observable point-like No crystallization after flow (kinetics) nuclei row nuclei -- No oriented nuclei shish nuclei – Yes objective colored large nucleation density shear Microscopy no no yes Dilatomery yes yes no DSC yes yes no Rheometry yes yes yes develop a method which is (more) reliable, simple, also works with flow. suspension-based model[1] measure G*(T) ? space filling f Avrami Equation nucleation density N(T) 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 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 objective observable point-like No nuclei crystallization after flow row nuclei -- No oriented nuclei shish nuclei – Yes (orientation and kinetics) 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! Pressure-quench Set-up Protocol Multi-Pass Rheometer (MPR) Erase history at 190oC and cool to 134oC A apparent wall shear rate: 60 1/s shear time: 0.8s 300bar reference 50bar Pressure-quench Pressure Quench 50bar t=0s t=17s a c c b b a flow highly oriented row nuclei crystals twisted lamellae Pressure-quench Set-up Protocol Multi-Pass Rheometer (MPR) 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 results Pressure Quench no annealing 0s 8.5s 17s 102s annealing (ta=22min) 0s 8.5s 34s 93.5s results relaxation of orientation theoretical (tube model) experimental results relaxation of orientation theoretical (tube model) 1.51 D 3 e Z 3 1 Z 2 For HMW tail (1,480,000 g/mol) at 134 oC Long lifetime of orientation Besides molecular mobility, other effect exists. experimental results relaxation of orientation theoretical (tube model) 1.51 D 3 e Z 3 1 Z 2 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 results relaxation of orientation theoretical (tube model) 1.51 D 3 e Z 3 1 Z 2 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 results average nuclei density no annealing annealing (ta=22min) specific (200) diffraction (equatorial, off-axis or meridional) randomization of c-axes content of twisting overgrowth (nuclei density) results average nuclei density no annealing annealing (ta=22min) specific (200) diffraction (equatorial, off-axis or meridional) randomization of c-axes content of twisting overgrowth (nuclei density) some nuclei relax within annealing lower nuclei density 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 results flow field in the slit sample X-ray diamond window shear WAXD results after flow the whole sample in situ characterization the first formation outer layer (strongest flow) objective observable point-like No nuclei row nuclei -- No oriented nuclei shish nuclei – Yes formation during flow experimental combining rheology (Multi-pass Rheometer ,MPR) and X-ray MPR [email protected] Pilatus (30 frame/s) to track shish formation during flow experimental combining rheology and X-ray X-ray MPR [email protected] flow time 0.25s Pressure difference and shish during flow Pilatus (30 frame/s) results rheology “upturn” P Pbottom Ptop iPP (HD601CF) at 145oC wall stress For w ≥ 240 , pressure difference deviates from the steady state and shows an “upturn”. 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 results rheology birefringence “upturn”[1] “upturn” 0.06 MPa oriented precursors iPP (HD601CF) at 145oC iPP (PP-300/6) at 141oC[1] ∆P “upturn” precursory objects form faster at higher shear rate [1] G Kumaraswamy et al Macromolecules 1999, 32, 7537 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 results apparent shear rate of 400s-1 and T = 145oC 2). from precursor to shish 2D SAXS time 0.10s 0.20s shish streak 0.23s flow stops at 0.25s 0.26s 0.40s results apparent shear rate of 400s-1 and T = 145oC 2). from precursor to shish SAXS 2D SAXS flow q(1/ nm) az () flow shish SAXS equatorial Intensity 0.2 10 0.018 10 I (az, q)d az d q shish formation around 0.23s results apparent shear rate of 400s-1 and T = 145oC rheological response SAXS flow flow ∆P “upturn” around 0.1s shish formation around 0.23s Precursors develop into shish 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. 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. results SAXS results linked to the FIC model Nucleation and growth model[1] growth rate number of nuclei N N (Be,highMw , T ) L L(Be,averageMw , T ) length growth total length of shish Ltot t 4 4 a g 0 T 0 L 0 a T g0 N HMW (t ') 1 dt ' avg (t ) 1 dt tcri [1] F. Custodio et al. Macromol. Theory Simul. 2009, 18, 469 conclusions observable point-like conclusions innovation Suspension-based model • The combined effect of nucleating agent and flow on the nucleation density can be assessed. Pressure Quench • • • Formation of row nuclei is visualized. Stable nuclei can survive within 22-min annealing. Unstable ones relax within 22-min annealing. No nuclei row nuclei -- No oriented nuclei Combining rheology and synchrotron X-ray shish nuclei – Yes • • • 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. Acknowledgements Prof. Gerrit Peters Dr. Luigi Balzano Ir. Tim van Erp Ir. Peter Roozemond Ir. Martin van Drongelen Dr. Giuseppe Portale Thank you for your attention