Shear-induced crystallization of polyethylene

1
Shear-induced crystallization of polyethylene
(see Heeley, Morgovan, Bras, Dolbnya, Gleeson,
Ryan, Phys. Chem. Comm. (2002) 5, 158-160.
Shear-induced crystallization of polyethylene
studied by small- and wide-angle X-ray scattering
(SAXS/WAXS) techniques) In situ study of
development of shear-induced macrostructure of
PE injection molding gt shear flow in
polymer changes crystallization kinetics
morphology chain alignment gt 'shish kebab'
structure
2
Shear-induced crystallization of polyethylene
(see Heeley, Morgovan, Bras, Dolbnya, Gleeson,
Ryan, Phys. Chem. Comm. (2002) 5, 158-160.
Shear-induced crystallization of polyethylene
studied by small- and wide-angle X-ray scattering
(SAXS/WAXS) techniques) In situ study of
development of shear-induced macrostructure of
PE synchrotron radiation using shear cell
heating stage 5 sec/frame after shear (100
pulses/sec for 5 10 sec)
crystallization temperature
3
Shear-induced crystallization of polyethylene
Results stacking of lamellae along shear
direction
shear direction
lower MW - less orientation
4
Shear-induced crystallization of polyethylene
More results invariant vs crystallization
time
lower MW - less orientation
5
Pores in polymers carbons
(see Olivier, Lagasse, Schaeffer, Barnes, long,
Macromolecules (1996) 29, 8515-8621. SA
small-angle-scattering study of the
pore-orientation periodicity in porous polymer
and carbon materials) Banded spherulites gt
carbon foams crystallized blend of maleic
anhydride (MA) polyacrylonitrile (PAN) bands
are 3.5 mm in width in this system (can use
SAXS) sublimate MA pyrolyze gt carbon foams
(98 void volume)
6
Pores in polymers carbons
(see Olivier, Lagasse, Schaeffer, Barnes, long,
Macromolecules (1996) 29, 8515-8621. SA
small-angle-scattering study of the
pore-orientation periodicity in porous polymer
and carbon materials)
7
Pores in polymers carbons
(see Olivier, Lagasse, Schaeffer, Barnes, long,
Macromolecules (1996) 29, 8515-8621. SA
small-angle-scattering study of the
pore-orientation periodicity in porous polymer
and carbon materials)
q4
averages of intensity data around azimuth - not
on absolute scale
8
Pores in polymers carbons
(see Olivier, Lagasse, Schaeffer, Barnes, long,
Macromolecules (1996) 29, 8515-8621. SA
small-angle-scattering study of the
pore-orientation periodicity in porous polymer
and carbon materials)
q4
sharp polymer/void interface
averages of intensity data around azimuth - not
on absolute scale
9
Pores in polymers carbons

10
Pores in polymers carbons

Plots of intensity differences from intensity
averages over 22 positions
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Pores in polymers carbons

Plots of intensity differences from intensity
averages over 22 positions Plots repeat at 3 4
mm translation interval
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Pores in polymers carbons

Plots of sector averages of intensity vs
translation position
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Pores in polymers carbons

Before pyrolysis After pyrolysis
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Pores in polymers carbons
Observation in as-crystallized blend bands
move when sample is rotated around growth
direction indicates rotation of crystal
orientations substantiated by high-angle
x-ray studies
orthorhombic MA cells
15
Pores in polymers carbons
Observation in as-crystallized blend bands
move when sample is rotated around growth
direction indicates rotation of crystal
orientations substantiated by high-angle
x-ray studies band motion observed in pyrolyzed
mat'l gt anisotropic pore rotation
orthorhombic MA cells
16
Pores in polymers carbons
band motion observed in pyrolyzed mat'l
gt anisotropic pore rotation
pore shape assumed ellipsoidal
17
Pores in polymers carbons
band motion observed in pyrolyzed mat'l
gt anisotropic pore rotation substa
ntiated by oscillation in Porod data plots
pore shape assumed ellipsoidal
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Pores in polymers carbons
Porod constant, KP, for isotropic case For
anisotropic case Also, for average chord
length, ltLVgt, inside pore
vol. fact.
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Pores in polymers carbons
Porod constant, KP, for isotropic case For
anisotropic case
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Pores in polymers carbons
Porod constant, KP, for isotropic case For
anisotropic case