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THERMAL GRADIENT INTERACTION CHROMATOGRAPHY (TGIC) FOR
MICROSTRUCTURE ANALYSIS OF POLYOLEFINS
Rongjuan Cong1, Willem deGroot1, Wallace Yau1 Lonnie Hazlitt1, Al Parrott1, Ray Brown1
Michael Cheatham1, Matt Miller2, Zhe Zhou2
1Basic Plastics Characterization
2Analytical Sciences
The Dow Chemical Company
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Outline
Overview of SCB Analytical Tool Box What is TGIC?
― Triple Detector TGIC Capability Examples Experimental Set up Conclusions
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Tool Box of SCB Distribution Analysis
CategoryCategory Separation mechanism CharacteristicsCharacteristics
TREF
CRYSTAF
CEF
Ability of polyolefin chains to crystallize from a dilute solution upon temp changes in a single solvent
Commercially available detectors (Light scattering, viscometer and IR)SCB up to 9 mol%*Cocrystallization
High-temp LC
(Solvent/non solvent)
Solubility and adsorption of polyolefin chains with stationary phase upon solvent composition change
SCB range 0 to 100 mol% comonomerFast for 1D HT-LCLack of satisfactory detector for Mw, IV and composition
*Commonly used conditions
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Proposed separation mechanismProposed separation mechanismInteraction and desorption of polyolefin chains from stationary phase upon
temperature change in an isocratic solvent
AdvantagesAdvantagesChoice of commercial detectors—For example, IR-4, IR-5, LS and various
viscometersReducing the cocrystallization commonly observed in CEF/CRYSTAF/TREF
Stationary PhaseStationary Phase―HYPERCARB column and various other columns
Mobile PhaseMobile Phase―Choice of isocratic solvents. Pure o-dichlorobenzene
TGIC for Polyolefins
solutionin versussubstrateon polymer ofamount
)(ln
pK
R
S
RT
HpK
+
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TGIC for wide range of comonomer content
-0.08
0.02
0.12
0.22
0.32
-5 15 35 55 75 95 115 135 155
Oven/Column Temp (C)
IR-4
Raw
Sig
nal 50mol% octene
32mol% octene
0mol% octeneFor HDPE:Crystallization temp by CRYSTAF: ~85oC
Melting temp by CEF/ATREF: 102oC
Melting temp by DSC 135oC
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0
20
40
60
80
100
120
140
160
0 10 20 30 40 50
Octene mole%
Peak
Tem
p (C
)
TGIC for wide range of comonomer content
•Down to 30° C, TGIC may determine octene content for LLDPE's 38mol% octene.
•Covering all the practical product applications.
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DSC for wide range of comonomer content
0.0
1.0
2.0
3.0
4.0
5.0
-40 10 60 110
Temp (oC)
He
at
Flo
w (
W/g
)
15mol% octene
HDPE with 0 mol% comonomer
8.5 mol% octene
DSC
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TGIC CEF
-0.02
0.03
0.08
0.13
0.18
0.23
40 60 80 100 120 140 160 180
Oven/Column temp (oC)
IR-4
Mea
suri
ng s
enso
r
Down to 40oC
13.8mol% octene
-2
8
18
28
38
22 42 62 82 102
CEF Elution Temp (C)IR
-4 R
aw S
igna
l
Down to 30oC
8.5mol% octene
TGIC run times are competitive with CEF runs.
Insensitive to Mw for HDPE from Mw ≥~30,000
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Triple detector TGICIR-4 detector
• (Methyl and Methylene channels) CCD and CH3/1000C
Two angle LS detector• Mw and Rg if interested• Mw versus comonomer distribution
Differential viscometer • IV and possible LCB information• IV versus comonomer distribution
Example: solution blend of a-PP (Mw20,000)/i-PP (Mw 265,000)/HDPE (115,000) 33.3/33.3/33.3 (wt/wt/wt)
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-0.01
0.01
0.03
0.05
0.07
0.09
35 55 75 95 115 135 155 175
Oven/Column Temp (C)
IR-4
Raw
Sig
nal
Blend of a-PP/i-PP/HDPE—IR4 Detector
a-PP
i-PP
HDPE Baseline resolved
Precise quantification of each component
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Blend of a-PP/i-PP/HDPE
• Mw info
• Detailed microstructure
Mw LS/IR-4
-0.01
0.01
0.03
0.05
0.07
0.09
35 55 75 95 115 135 155 175
Oven/Column Temp (C)
IR-4
Raw
Sig
nal
0.57
0.62
0.67
0.72
0.77
LS 9
0 R
aw S
igna
l
a-PP (20,000)
i-PP (Mw 265,000)
HDPE (115,000)
-0.01
0.01
0.03
0.05
0.07
0.09
35 55 75 95 115 135 155 175
Oven/Column Temp (C)
IR-4
Raw
Sig
nal
0.57
0.62
0.67
0.72
0.77
LS 9
0 R
aw S
igna
l
-0.01
0.01
0.03
0.05
0.07
0.09
35 55 75 95 115 135 155 175
Oven/Column Temp (C)
IR-4
Raw
Sig
nal
0.57
0.62
0.67
0.72
0.77
LS 9
0 R
aw S
igna
l
a-PP (20,000)
i-PP (Mw 265,000)
HDPE (115,000)
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-0.01
0.01
0.03
0.05
0.07
0.09
35 55 75 95 115 135 155 175
Oven/Column Temp (C)
-0.018
0.022
0.062
0.102
Blend of a-PP/i-PP/HDPE—Composition Mode of IR-4 Detector
a-PP
i-PP
HDPEMethylene channelMethyl channel
Ratio of the two channels is correlated to CH3/1000C
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-4.4
-3.4
-2.4
-1.4
-0.4
0.6
1.6
-40 -10 20 50 80 110 140 170 200
Temp (C)
Hea
t fl
ow
(w
/g)
DSC of a-PP/i-PP/HDPE blend
Cocrystallization during cooling
HeatingFailed to quantify i-PP wt%No info about a-PP
HDPE 132.0oC i-PP 158.9oC
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CRYSTAF of a-PP/i-PP/HDPE blend
0
2
4
6
8
10
12
25 35 45 55 65 75 85 95
Temperature (ºC)
De
riv
ati
ve
(d
W/d
T)
0
10
20
30
40
50
60
70
80
90
100
Cu
mu
lati
ve
(w
t%)
a-PP (expected 35.0 wt%)Measured 23.6wt%Unable to tell Mw of SF
HDPE
i-PP
Limited data point. Difficult to deconvolute
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-1
1
3
5
7
9
11
13
20 40 60 80 100 120
Temperature (C)
Ma
ss
(d
Wf/
dT
)
0
1
2
3
4
5
6
7
Lo
gM
W
CEF of a-PP/i-PP/HDPE blend
No baseline separation between
HDPE and i-PP
a-PP HDPE
i-PP
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Triple detector (IR/LS/DP) TGIC
AdvantagesAdvantages Provides abundant (triple detector) and unique information
regarding microstructure of polyolefins in short experimental time»CCD, Mw versus CCD, IV versus CCD, Rg versus CCD
Elimination of the cocrystallization commonly observed in CEF, CRYSTAF and TREF
»Making modeling and deconvolution of CCD distribution feasible. Bringing new opportunity to characterize new polyolefins with
more complex microstructures
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0
0.05
0.1
0.15
0.2
0.25
-4-20246810121416
Apparent mol% C8
WF/
d(C
8 m
ol%
C8)
Comparison of TGIC with Solvent Gradient HT-LC
0
0.05
0.1
0.15
0.2
0.25
-4-20246810121416
Apparent mol% C8
WF/
d(m
ol%
C8)
Injection 1
Injection 2
Injection 3
-0.01
0
0.01
0.02
0.03
0.04
0.05
0.06
90 100 110 120 130 140 150 160
A quick TGIC
0
0.05
0.1
0.15
0.2
0.25
-4-20246810121416
Apparent mol% C8
WF/
d(m
ol%
C8)
Injection 1
Injection 2
Injection 3
-0.01
0
0.01
0.02
0.03
0.04
0.05
0.06
90 100 110 120 130 140 150 160
A quick TGIC
TGICHT-LC
Similar Comonomer distribution.
TCB
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Repeatability of TGIC
-1
1
3
5
7
9
40 60 80 100 120 140 160 180
Oven/Column Temp (C)
IR-4
Sig
nal 10 Consecutive injections
with different sample preps
Excellent in repeatability
Tp=134.86±0.17oCRSD=0.25%
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Experimental Set-up
70 vial autosampler, triple detector and subambient capability
Time
Loading Loading ColumnColumn Adsorption*Adsorption* DesorptionDesorption
Final/Final/CleaningCleaning
Tem
p
Detectors (IR4-LS-DP)Pump Injector
Solv
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• TGIC is a new technique to characterize polyolefins. Proposed mechanism is the interaction of polyolefin chains with stationary phase (column) upon temp change in a constant solvent composition
• TGIC overcomes the detector difficulty in solvent gradient HT-LC
• TGIC is a versatile technique, capable of providing comonomer composition from 0 to 100 mol% octene
• With triple detector, TGIC provides abundant information about polyolefin microstructure to compliment quadruple detector GPC
Conclusions
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Questions?
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Experimental set up for finding anchoring temp of HDPE
HDPE loaded at different temp onto HYPERCARB column
Heating rate 3oC/min
80
100
120
140
160
0 5 10 15
Time (min)
Ove
n/co
lum
n Te
mp
(C) 140oC
130oC120oC
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0.1
0.2
0.3
0.4
0.5
120 130 140 150 160 170
Oven Temp (oC)
IR-4
Raw
Sig
nal
Anchoring/desorption temp of HDPE
• Anchoring temp of HDPE in ODCB: ~137oC. Desorption temp: 147oC
• Anchoring/desorption temp depended on solvent.
• Anchoring temp is insensitive to expt parameter, but related CEF
140oC130oC120oC
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Interaction of polymer with substrate
Chi
log
(Kp
)
po
siti
ven
egat
ive
>0.5<0.5
SUCCESS!Adsorption D
isso
lutio
n B
ound
ary
R
S
RT
HpK
)ln(
Chi
log
(Kp
)
po
siti
ven
egat
ive
>0.5<0.5
SUCCESS!Adsorption D
isso
lutio
n B
ound
ary
Chi
log
(Kp
)
Chi
log
(Kp
)
po
siti
ven
egat
ive
>0.5<0.5
SUCCESS!AdsorptionSUCCESS!Adsorption D
isso
lutio
n B
ound
ary
R
S
RT
HpK
)ln(