Advanced Fractionation Techniques for
Complex Polyolefins
Harald Pasch
SASOL Chair of Analytical Polymer Science
Department of Chemistry and Polymer Science,
University of Stellenbosch, South Africa
1
Polyolefin Analysis
Complex Structures
New Copolymers
Cl
Zr
+
R
R = n-B uty l, n-D ecyl or n-H ex adecy l
Fractionation Techniques ?
1
Cl
MAO
New Applications
fraction
R
chemical
Chemical
composition
composition
TREF
CRYSTAF
2
Molecular
hydrodynamic
size
volume
HT-SEC
Polyolefins – The Most Common Polymers
H2
C
H2
C
C
H2
H2
C
H2
C
C
H2
C
H2
n
polyethylene
CH
CH
3
CH
3
CH
3
3
CH
H 3C
C
H2
C
H2
n
C
H2
polypropylene
3
C
H2
3
Where are the problems ?
Polyolefins just CH, CH2 and CH3 .... ?????
H 3C
H 3C
H 3C
H 3C
H 3C
H 3C
H 3C
H 3C
H 3C
Isotactic polypropylene (high crystallinity)
Narrower PDI (Metallocene)
Syndiotactic polypropylene
Atactic polypropylene (low crystallinity)
4
Broader PDI (Ziegler-Natta)
Polyolefins just CH, CH2 and CH3 .... ?????
1
2
3
Molecular structure
Morphology
Physical Properties
MM,MMD
SCB distribution
SCB content
Crystal size, crystal
size distribution
tie molecules
interfacial order
haze,gloss, clarity,
tear strength, tensile
strength,impact
strength
Instrumentation
required
Instrumentation
required
Instrumentation
required
HT-SEC CRYSTAF,
TREF DSC
NMR, FTIR
DSC, DMA
NMR,
Microscopy AFM, SEM
Different test
equipment
5
Why does chain structure influence properties?
Structures
LDPE
Density
0.935
6
LLDPE
0.929 -0.945
HDPE
0.940 - 0.965
Branch type influences
the crystal structure
Distribution of the
branches ???
Change
in SEM
Crystal Morphology as a Result of Blending
Results:
LDPE
60% LDPE + 40% Plastomer
poly(ethylene-1-octene)
7
Molar Mass Analysis
8
High-Temperature SEC Polymer Labs Model PL GPC 220
Stationary phase:
Cross-linked PS
Mobile phase:
Trichlorobenzene
Temperature:
140 oC
Calibration: PS, PE
Detectors:
RI, ELSD, IR, LS, Vis
9
HT-SEC and FTIR of an Oxidized Polyethylene
?
10
Universal LC-FTIR Coupling
pump +
injector
RI-detector
Separation
HPLC / GPC
LCTransform
Abs
Identification
0.3 5
0.3 0
0.2 5
3. 0
2. 5
0.1 5
0.1 0
2. 0
0.0 5
0.0 0
1. 5
2 000
c m-1
FTIR spectrometer
11
series of spectra
Ni c
0.2 0
SEC-FTIR of an Ethylene-Methacrylic Acid Copolymer
Gram Schmidt 0.12
-1
1165
ratio 1740 cm /CHn
0.3
90
1377
17/0 3, GK 0 033/58 /2
95
1739
1705
100
-1
80
-1
0.2
n
0.08
718
70
%T
ratio 1720 cm /CH
1472
75
0.10
729
ratio 1704 cm /CHn
85
65
50
ratio
55
0.1
0.06
17 /03, G K 003 3/58 /2
9 9.5
9 9.0
9 8.5
45
9 8.0
3500
0.0
3000
9 6.5
2500
2000
1500
Wavenumbers (cm-1)
3500 3000
2500
2000
1500
%Transmi ssion
4000
9 7.0
2915
35
0.04
9 7.5
2848
40
Intensity
60
9 6.0
1000
9 5.5
0.02
1000
9 5.0
9 4.5
9 4.0
-0.1
9 3.5
9 3.0
1705
Wellenzahl [cm-1]
9 2.5
0
10
20
9 1.5
1 850
1 800
30
0.00
1739
9 2.0
1 750
1 700
1 650
1 600
W elle nza hlen (c m -1)
Elution volume [ ml ]
1800
12
1750 1700 1650 1600
SEC-FTIR Analysis of a Polyolefin Blend
13
Separation by Crystallizability: Chemical Heterogeneity
fraction
CRYSTAF
chemical
composition
TREF
•
•
hydrodynamic
volume
HT-SEC
Temperature Rising Elution Fractionation (TREF)
Crystallization Analysis Fractionation (CRYSTAF)
 separation with regard to chemical composition
14
Separation by Crystallizability: Chemical Heterogeneity
•
Based on Flory-Huggins
expression for polymerdiluent mixtures
•
diluent: solvent, comonomer
•
melting point depression is
a function of noncrystallizable comonomer
content
•
15
chemical composition
separation = separation by
crystallizability
1/Tm - 1/Tmo = -(R/DHu) ln NA
Tm
melting point copolymer
Tmo
melting point homopolymer
DHu heat of fusion per repeat unit
NA
mole fraction of comonomer
Temperature Rising Elution Fractionation
 D issolve the sa m p le in hot T C B or o-D C B
 L oa d the colu m n w ith the h ot solutio n
 C ry stallize the sa m p le by slow tem p.-prog ra m m ed cooling
 2 -4 K /hour ta ke 6 0 -3 0 hours
 E lute th e sa m p le by slow tem p.-prog ra m m ed heating
 8 K /hou r ta ke 1 5 -20 hours
16
L . W ild , A d v. P olym . S ci. 9 8 (1 99 0 ) 1 -47
TREF Separation Mechanism
The slow cooling rate is the most important factor in achieving good
separation
The slow cooling rate minimizes the effects of co-crystallization and
molar mass influences.
Typical cooling rates would be about 2°C/hour
It takes about 2-3 days to cool!!
17
Temperature Rising Elution Fractionation
Comparison of typical LLDPE and LDPE
18
Temperature Rising Elution Fractionation
Hypothetical samples with same MMD and crystallinity distribution but
different dependency on each distribution
19
Temperature Rising Elution Fractionation
Automatic Cross-Fractionation System TREF-SEC
S. Nakano, Y. Goto, J. Appl. Polym. Sci. 26 (1981) 4217
20
Temperature Rising Elution Fractionation
TREF-SEC Analysis of a Blend of Two Polyethylenes
S. Nakano, Y. Goto, J. Appl. Polym. Sci. 26 (1981) 4217
21
Crystallization Analysis Fractionation
IR
detector
dW/dT
W [%]
100
6
4
60
40
2
20
0
20
22
30
40 50 60 70
Temperature [°C]
80
0
90
W [%]
dW/dT
80
Crystallization Analysis Fractionation
23
Crystallization Analysis Fractionation
2
140
120
Typical temperature cycle
100
1
4
6
80
5
60
40
Zone 3
Zone 1
Zone 2
16
100
0
100
200
300
400
500
600
700
T im e (m in )
80
F irs t D e riv a tiv e
12
10
60
8
6
40
S o lu b le fra ctio n
4
20
2
0
0
0
24
10
20
30
40
50
o
T e m p e ra tu re ( C )
60
70
80
d w /d T
Typical crystallization curve
14
In fra re d S ig n a l
C u m u la tiv e F ra ctio n (% )
o
T e m p e ra tu re ( C )
3
Crystallization Analysis Fractionation
Crystaf analysis of a PP blend
Comparison of TREF and
CRYSTAF
25
CRYSTAF: Analysis of Copolymers and Blends
35
HDPE
60
15
40
10
0
0
30
40
50
60
70
80
4
2
20
5
LLDPE
6
80
20
20
Lupolex 25 Q F A
100
W [% ]
d W /d T
25
Lupolex 18 K F A
8
d W /d T
30
W
dW /dT
0
20
90
30
40
60
70
80
90
100
T em perature [°C ]
T em perature [°C ]
W
d W /d T
12
50
HDPE/PP 50
: 50
d W /d T
8
HDPE/LDPE
4:96
100
100
10
80
40
2
20
0
0
30
26
40
50
60
70
80
T e m p e ra tu re [°C ]
90
100
d W /d T
4
60
4
40
2
0
30
20
0
40
50
60
70
80
T e m p e ra tu re [°C ]
90
100
W [% ]
60
6
80
6
W [% ]
d W /d T
8
CRYSTAF: Analysis of Copolymers and Blends
Propene--Olefin Copolymers
m elting tem perature (D S C )
cry stallization tem perature (D S C )
cry stallization tem perature (C R Y S T A F )
160
15
Propene-Octene
8.4
8.6
8.8
o
8.2
10
T em perature [ C ]
140
dW /dT
3.1
5
120
100
80
60
40
20
0
40
50
60
70
80
90
100
0
0
o
T em p eratu re [ C ]
1
2
16
com on om er [m ol-% ]
18.10
14
12
18.9
18.4
18.11
3
Propene-Octadecene
Propene-Olefin Copolymers
18.6
10
Crystallization Temperature
dw /dT
3.1
8
6
4
2
0
40
50
60
70
80
90
100
80
75
70
65
Octene
60
55
50
Decene
45
40
PP
Tetradecene
Octadecene
35
30
0
1
2
o
T em p eratu re [ C ]
27
% Comonomer
3
4
CRYSTAF (in particular when coupled to IR sensor)
excellent technique but very time consuming
Fast and selective techniques are required
liquid chromatography is a good candidate
Polyolefins are soluble only at high temperatures
unconventional stationary and mobile phases ???
28
Elution Behaviour of Polyolefins in High Temperature
Chromatography (HT-HPLC) Using Interactive Stationary
Phases
polyolefin must dissolve in the mobile phase
screening of solubility
polyolefin must interact with the phase system
screening of mobile and stationary phases
29
Solvents and Columns
Trichlorobenzene
Cyclohexanone
polarity
Decaline
Dimethylformamide
normal phase systems: SiO2 (ZrO2, TiO2, Al2O3)
reversed phase systems:
Diol…
CN…
Phenyl…
polarity
30
C8…
C18
Screening of Stationary Phases for HT-HPLC
lo g M
Stationary phase:
5
dimethylsiloxanemodified silica gel
CH3
4
Cl Si Cl
CH3
 Benzylalcohol
CH3 CH3
H 2O
OH
SiO 2
Si
3 O
x Cyclohexylacetate
O
n
OH
 DMF
2
SiO 2
 Cyclohexanone
31
3
e lu tio n tim e [m in ]
4
Screening of Stationary Phases for HT-HPLC
Stationary phase: dimethylsiloxane-modified silica gel, solvent: TCB
lo g M
SEC conditions
with regard to PP
()
Limiting conditions
with regard to PE
()
100000
10000
1000
mobile phase: EGMBE
2 .0
32
2 .5
3 .0
3 .5
e lu tio n tim e [m in ]
4 .0
Screening of Stationary Phases for HT-HPLC
Stationary phase: dimethylsiloxane-modified silica gel, solvent: TCB
PE
PP: SEC
PE: Limiting conditions
PP 36k + PE 34k
[V ]
0 .2
P P 3 6 kg /m o l
0 .1
P P 5 7 kg /m o l
P P 4 3 8 kg /m o l
PP 57k + PE 66k
PP 438k + PE 500k
0 .0
1 .5
mobile phase: EGMBE
33
2 .0
2 .5
3 .0
3 .5
e lu tio n tim e [m in ]
4 .0
4 .5
Analysis of PE-PMMA Block Copolymers: SEC and FTIR
0 .3 5
1 .0
PMMA
?
PE
9 9 3 .3 1
0 .1 0
0 .3
7 1 7 .5 2
0 .1 5
0 .4
7 5 8 .7 8
0 .2 0
1 1 9 1 .5 4
0 .5
A bsorbance
0 .6
0 .2
0 .0 5
9 5 5 .2 2
8 4 0 .5 0
0 .2 5
0 .7
1 1 4 8 .3 4
0 .3 0
A bsorbance
D e te c to r S ig n a l (m V )
0 .8
1
8
9
11
1 7 2 8 .9 8
T
T
T
T
0 .9
0 .1
0 .0 0
0 .0
3
1 x1 0
4
1 x1 0
5
1 x1 0
6
1 x1 0
7
1 x1 0
M o la r M a s s (g /m o l)
4000
3000
2000
-1
W ave n u m b ers (cm )
1000
y
Multimodal distribution
blend or copolymer ?
Chemical composition as a
function of molar mass ?
34
MMA and ethylene units can be
identified, but is it a copolymer or
a polymer blend ?
Analysis of PE-PMMA Block Copolymers: Coupled SEC-FTIR
0 ,5
G ra m -S c h m id t
A
G ra m -S c h m id t
-1
PE
W a v e h e ig h t C h e m ig ra m (1 7 3 0 c m )
1 ,0
W a v e h e ig h t C h e m ig ra m (1 7 3 0 c m )
-1
W a v e h e ig h t C h e m ig ra m (7 2 0 c m )
PMMA
C
-1
-1
W a v e h e ig h t C h e m ig ra m (7 2 0 c m )
E t / (E t + M M A )
0 ,4
E t / (E t + M M A )
0 ,8
S ig n a l In te n sity
Chemical composition
as a function of molar mass is
visualized !
0 ,2
0 ,1
0 ,2
0 ,0
0 ,0
0
5
10
15
R e te n tio n T im e (m in )
PE-b-PMMA
20
25
0
B
-1
W a v e h e ig h t C h e m ig ra m (7 2 0 c m )
G ra m -S c h m id t
5
Homopolymers and
copolymers can
be
D
identified !
10
15
20
25
R e te n tio n T im e (m in )
-1
W a v e h e ig h t C h e m ig ra m (1 7 3 0 c m )
E th yle n e R a tio
0 ,4
E th yle n e R a tio
S ig n a l In te n sity
0 ,3
0 ,6
G ra m -S c h m id t
0 ,6
-1
W a v e h e ig h t C h e m ig ra m (1 7 3 0 c m )
0 ,3
-1
W a v e h e ig h t C h e m ig ra m (7 2 0 c m )
E t / (E t + M M A )
E t / (E t + M M A )
0 ,5
0 ,2
S ig n a l In te n sity
0 ,3
0 ,2
E th yle n e R a tio
PE
0 ,1
E th yle n e R a tio
S ig n a l In te n sity
0 ,4
0 ,0
0 ,1
0 ,0
-0 ,1
-0 ,1
0
5
10
15
R e te n tio n T im e (m in )
35
20
25
0
5
10
15
R e te n tio n T im e (m in )
20
25
Analysis of PE-PMMA Block Copolymers
What about interaction
chromatography ?
SEC
molar mass separation
LC-CC
36
chemical composition separation
Analysis of PE-PMMA Block Copolymers: Gradient HPLC
2
A
Column:
Nucleosil 300 C18
Temperature: 140C
Mobile phase: gradient from100 % DMF
to 100 % TCB
1
4
3
1-
P M M A M n = 8 2 9 0 0 0 g /m o l
2-
P M M A M n = 2 2 2 0 0 g /m o l
3-
P M M A M n = 1 7 3 0 g /m o l
4-
P E M n = 1 1 1 0 g /m o l
6
5 a + b - P E M n = 1 2 0 0 0 g /m o l
6-
P E M n = 1 1 4 0 0 0 g /m o l
5b
S ignal Intensity (m V )
5a
B
7
PMMA
8
PE
9
T1
PE-b-PMMA
10
T8
T9
0
2
4
6
8
10
12
o
T e m p e ra tu re ( C )
37
14
16
18
20
22
Analysis of PE-PMMA Block Copolymers: Gradient HPLC-FTIR
10
A
1
G ra m -S c h m id t
-1
---- PMMA
1730
cm
P e a k -h e ig h t C
h e m ig ra m
(1 7 3 0 c m
A b so rp tio n In te n sity
8
8x
-1
)
-1
P e a k -h e ig h t C h e m ig ra m (7 2 0 c m )
----- PE 720 cm-1
6
PE
4
2
3
2
0
0
2
4
6
8
10
12
14
16
18
20
22
High-Temperature Gradient
HPLC as a New Tool for the
Analysis of Olefin Copolymers
24
R e te n tio n T im e (m in )
10
B
4
5
G ra m -S c h m id t
-1
PMMA
A b so rp tio n In te n sity
8
P e a k -h e ig h t C h e m ig ra m (1 7 3 0 c m )
5x
-1
P e a k -h e ig h t C h e m ig ra m (7 2 0 c m )
6
6
PE-b-PMMA
7
4
2
0
0
38
2
4
6
8
10
12
14
16
R e te n tio n T im e (m in )
18
20
22
24
Polymer Labs‘ High-Temperature Gradient HPLC System
39
Separation System for PE-PP Blends
PP
PE
M
signal
% TCB
Time [min]
40
Separation System for PE-PP Blends
1 ,0
1,5
B le n d M o p le n H P u n d P E 1 2 8 .0 0 0
PE
PP
propylene-rich
Detektos Signal (V)
0 ,8
0 ,6
E L S D [V ]
BASELL EPM-S1-D 20837-28
0 ,4
0 ,2
1,0
ethylene-rich
PP
0,5
0 ,0
0,0
0
2
4
6
8
10
E lu tio n s v o lu m e n (m l)
12
0
2
4
6
8
10
12
Elutions Volumen (mL)
column: Nucleosil 500
mobile phase: EGMBE-TCB
EP copolymer with 48% ethylene
T: 140oC
detector: ELSD
sample solvent: TCB
41
L.-C. Heinz, H. Pasch, High-Temperature Gradient HPLC for the Separation of
Polyethylene-Polypropylene Blends.Polymer 46 (2005) 12040
Separation System for EVA Copolymers
EVA 5% VA
EVA 12% VA
EVA 14% VA
EVA 19% VA
EVA 28% VA
EVA 45% VA
EVA 50% VA
EVA 60% VA
EVA 70% VA
PVAc-St. 164KD
PVAc-St. 32KD
PE-St. 126KD
10
8
6
4
100
stationary phase: silica gel
mobile phase: gradient of
decaline-cyclohexanone
80
60
PVAc
40
PE
% Cyclohexanon
Detektorsignal ELSD [V]
12
20
2
0
0
0
5
10
15
20
Elutionsvolumen [ml]
42
A. Albrecht, R. Brüll, T. Macko, H. Pasch: Separation of Ethylene-Vinyl Acetate Copolymers
by High-Temperature Gradient Liquid Chromatography. Macromolecules 40 (2007) 5545
Separation of Polyolefins by Tacticity
1,0
response
of ELSD
[Volts] 0,8 isotactic PP
atactic PP
linear PE
syndiotactic PP
0,6
0,4
0,2
Start of gradient
0,0
0
5
10
15
20
elution time [minutes]
25
stationary phase: carbon-based
mobile phase: gradient of
1-decanol-TCB
43
Schematic Protocol for 2D Separations
1
Vr
2
1
2
44
Two-Dimensional Chromatography (HPLC vs. SEC)
1. Dimension:
HPLC/LCCC
Degasser
Pump
Injector
2. Dimension:
GPC
HPLC
Column
Data
Processing
Degasser
Detector
Pump
SEC Column
Waste
45
High-Temperature 2D-HPLC in Stellenbosch
46
High-Temperature 2D-HPLC
Chromatographic conditions:
Stationary phase:
Mobile phase:
Operating temperature:
47
Hypercarb
gradient of decanol-TCB
160 oC
Ginsburg, A., Macko, T., Dolle, V., Bruell, R., Europ. Polym. J. 47 (2011) 319-329
High-Temperature LC-NMR
120°C
120°C
120°C
120°C
120°C
120°C
waste
48
High-Temperature LC-NMR
ELSD
Transfer
line
HT
Stop-flow
valve
Transfer
line
49
HT-SEC
1
a)
R
CH
1
CH
2
R
2
polyethylene
n
4
3
b)
R
CH
CH3
R
2
O
polymethyl methacrylate
n
O
CH3
2
8
7
c)
R
CH
7
2
CH
6
2
CH
CH3
R
2
O
O
CH3
5
50
n
copolymer EtMMA
On-flow High-Temperature SEC-NMR
min
sec
T=130°C
85.0
TCB
Impurities
80
80.0
75
75.0
70
70.0
65
65.0
60
60.0
55
55.0
4.0
51
3.5
3.0
2.5
2.0
1.5
1.0
0.5
50
ppm
On-flow High-Temperature SEC-NMR
Solvent subtraction of impurities
min
sec
T=130°C
85.0
80
80.0
75
PE
Mn=1.100
75.0
70
70.0
65
65.0
Et-MMA
Mn=10.600
60
60.0
55
flow rate 0.5mL/min, conc. 2+2+2 mg/mL,
300 µL injection volume, 5 Waters columns,
24 scans per FID, 1.24s repetition delay
4.0
52
3.5
3.0
2.5
55.0
2.0
1.5
1.0
0.5
50
ppm
PMMA
Mn=263.000
On-flow High-Temperature SEC-NMR
1
a)
R
CH
1
CH
2
R
2
n
1H
4
traces of the on-flow run
3
1
b)
R
CH
CH3
R
2
1O
a)
R
CH 2
O
CH
R
2
n
CH3
-CH3-
c) PE
1
n
2
4
7
c)b)
R
R
CH
8
73
7
2
CH3
6
CH
CH
CH2 2
CH3
R
2
5(m)
O
O
R
n
n
O
6(m)
b) Et-MMA
1
6(m)
1
O
a)
R
CH
2
CH3
CH
52
n
CH3
4(r)
2(r)
2
3(r)
4
3
b)
a) PMMA
4.0
R
CH
7
3.5
3.0
2.5
2.0
R
1.5
1.0
c)
ppm
R
CH
CH3
R
2
7
2
O
CHO 2
n
6
CH
8
CH3
2
O
CH3
2
53
O
CH3
85
On-flow High-Temperature SEC-NMR
Monomer composition (mol%)
100
1,0
80
0,8
E
60
40
0,6
0,4
MMA
20
0,2
0
0,0
10
15
Retention time (min)
4.0
54
3.5
3.0
2.5
2.0
1.5
1.0
0.5
ppm
20
Intensity of NMR projection
on-flow HT-SEC-NMR
of PE-PMMA Block Copolymer