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
DUBBLE@ESRF
Pilatus
(30 frame/s)
to track shish formation during flow
experimental
combining rheology and X-ray
X-ray
MPR
DUBBLE@ESRF
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,highMw , T )
L  L(Be,averageMw , 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