Pressure quench of flow induced crystallization
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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

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Pressure Quench of flow-induced crystallization

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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, 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


Pressure quench of flow induced crystallization

motivation

flow

structures

properties


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

objective

observable

point-like

nuclei

No

crystallization after flow

row nuclei -- No

oriented nuclei

formation during flow

shish nuclei – Yes


Pressure quench of flow induced crystallization

objective

observable

point-like

nuclei

crystallization after flow

(kinetics)

No

row nuclei -- No

oriented nuclei

shish nuclei – Yes


Pressure quench of flow induced crystallization

objective

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


Suspension based model 1

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


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

objective

observable

point-like

nuclei

No

crystallization after flow

(orientation and kinetics)

row nuclei -- No

oriented nuclei

shish nuclei – Yes


Pressure quench of flow induced crystallization

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 of flow induced crystallization

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


Pressure quench of flow induced crystallization

c

b

50bar

a

c

a

b

Pressure-quench

Pressure Quench

t=0s

t=17s

flow

highly oriented

crystals

twisted lamellae

row nuclei


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

no annealing

0s 8.5s 17s 102s

annealing (ta=22min)

0s 8.5s 34s 93.5s

results

Pressure Quench


Pressure quench of flow induced crystallization

results

relaxation of orientation

experimental

theoretical (tube model)


Pressure quench of flow induced crystallization

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.


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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)


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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)


Pressure quench of flow induced crystallization

objective

observable

point-like

nuclei

No

row nuclei -- No

oriented nuclei

formation during flow

shish nuclei – Yes


Pressure quench of flow induced crystallization

experimental

combining rheology (Multi-pass Rheometer ,MPR) and X-ray

Pilatus

MPR

[email protected]

(30 frame/s)

to track shish formation during flow


Pressure quench of flow induced crystallization

experimental

combining rheology and X-ray

X-ray

Pilatus

MPR

[email protected]

flow time 0.25s

(30 frame/s)

Pressure difference and shish during flow


Pressure quench of flow induced crystallization

For ≥ 240 , pressure difference deviates from the steady state and shows an “upturn”.

results

rheology

“upturn”

 wall stress

iPP (HD601CF) at 145oC


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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.


Pressure quench of flow induced crystallization

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.


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

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


Pressure quench of flow induced crystallization

Acknowledgements

Prof. Gerrit Peters

Dr. Luigi Balzano

Ir. Tim van Erp

Ir. Peter Roozemond

Ir. Martin van Drongelen

Dr. Giuseppe Portale


Pressure quench of flow induced crystallization

Thank you for your attention


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