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

flow structures properties motivation

[1] Swartjes F.H.M (2001) PhD thesis, Eindhoven University of Technology, NL [2] Hsiao B.S et al. (2005) Physical Review Letter, 94, 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

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

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

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

coloredlarge nucleation density shear Microscopyno yes Dilatomeryyes no DSCyes no Rheometryyes objective develop a method which is (more) reliable, simple, also works with flow.

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 ?

method suitable for combined effect of NA and flow Z Ma et al. Rheol Acta (2011) DOI /s suspension-based model iPP and U-Phthalocyanine (145 o C)

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

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

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

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

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

results 0s 8.5s 34s 93.5s annealing (t a =22min) Pressure Quench 0s 8.5s 17s 102s no annealing

experimental theoretical (tube model) results relaxation of orientation

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

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

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, iPP [1] relaxation of orientation

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)

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)

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

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

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

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