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
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, 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
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
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
colored large nucleation density
shear
Microscopy no no yes
Dilatomery yes yes no
DSC yes yes no
Rheometry yes yes yes
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 10.1007/s00397-010-0506-1
suspension-based model
iPP and U-Phthalocyanine (145oC)
objective
point-like
nuclei
oriented nuclei
crystallization after flow
(orientation and kinetics)
No
row nuclei -- No
shish nuclei – Yes
observable
increase Tequilibrium by pressure
decrease Texp 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 190oC and cool to 134oC
A apparent wall shear rate: 60 1/s
shear time: 0.8s
300barreference 50bar
50bar
flow
highly oriented
crystals
a
cb
row nuclei
Pressure-quench
Pressure Quench
a c
b
twisted lamellae
t=0s t=17s
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
300barreference 50bar
annealing after flow, ta=22min
results
0s 8.5s 34s 93.5s
annealing (ta=22min)
Pressure Quench
0s 8.5s 17s 102s
no annealing
experimental theoretical (tube model)
results
relaxation of orientation
experimental
2
3 1.513 1D eZ
Z
theoretical (tube model)
For HMW tail (1,480,000 g/mol) at 134 oC
results
Long lifetime of orientation
Besides molecular mobility, other effect exists.
relaxation of orientation
2
3 1.513 1D eZ
Z
theoretical (tube model)
For HMW tail (1,480,000 g/mol) at 134 oC
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
2
3 1.513 1D eZ
Z
theoretical (tube model)
For HMW tail (1,480,000 g/mol) at 134 oC
results
Long lifetime of orientation
Interaction between PE chains (or segments) at 134oC
[1] H An et al. J. Phys. Chem. B 2008, 112, 12256
iPP[1]
relaxation of orientation
annealing (ta=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 (ta=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
diamondwindow
sample
shear
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
DUBBLE@ESRF Pilatus
experimental
to track shish formation during flow
MPR
(30 frame/s)
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
rheology
iPP (HD601CF) at 145oC
bottom topP P P
wall stress
results
For ≥ 240 , pressure difference deviates from the steady state and shows an “upturn”.
w
“upturn”
rheology
iPP (HD601CF) at 145oC
results
iPP (PP-300/6) at 141oC[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 145oC
results
“upturn”
iPP (PP-300/6) at 141oC[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 = 145oC
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 = 145oC
2D SAXS
shish
streak
results
flow stops at 0.25s
flow
SAXS
results
2D SAXS
flow shish
SAXS equatorial Intensity
( )az
0.2 10
0.018 10( , ) az qI az q d d
(1/ )q nm
shish formation around 0.23s
2). from precursor to shish
apparent shear rate of 400s-1 and T = 145oC
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 = 145oC
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 = 145oC
t = 0.26s
t = 0.33s
t = 0.37s
results
shish
apparent shear rate of 320s-1 and T = 145oC
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 ,( , )high MwN N T eB
length growth ,( , )average MwL L T eB
4 40 0
0 0
( ') 1 ' ( ) 1crit t
tot T L T N HMW avgL a g a g t dt t dt
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
