Polyolefin Microstructure Characterization Using 3D-GPC-TREF Wallace W. Yau Lyondell Chemical Company Cincinnati Technology Center 11530 Northlake Drive Cincinnati, Ohio 45249 USA e-mail: wallace.yau@equistar.com ABSTRACT Gel permeation chromatography (GPC) separates polymers by size, and therefore provides a measure of polymer molecular weight distribution (MWD). Since long chain branching (LCB) adds to molecular weight more than to molecular size, adding a light scattering (LS) and a viscosity detector to GPC in the form of 3D-GPC also becomes a tool to detect polymer LCB and LCB distribution. However, GPC separation is insensitive to polymer short branching (SCB). For SCB distribution, we use the temperature rising elution fractionation (TREF) technique. TREF relies on the crystallization and dissolution process to separate polymers that have different levels of SCB. Adding a LS and a viscosity detector to TREF makes it possible to detect the molecular weight (MW) dependency across the polymer SCB distribution. Therefore, a fully automated hybrid system of 3D-GPC-TREF is a very effective tool for analyzing polymer branching architectures. Such structural information is highly useful to complement the thermal analyses and the rheological results for studying many areas of polymer interests where the understanding of polymer structure-property relationship is of central importance. The following examples of problem-solving application will be discussed: LCB differences between tubular and autoclave low density polyethylene (LDPE); LCB effect on draw down, neck-in, and heat seal of LDPE in coating application; reverse MW-SCB dependency of linear low density polyethylene (LLPDE); and “gel” versus “un-melt” issues in high density polyethylene (HDPE) films. INTRODUCTION In 1936, Imperial Chemicals, Inc. (ICI) issued the first patent for the manufacture of high pressure LDPE1. The manufacturing of HDPE began with the Ziegler-Natta (ZN) catalyst under low pressure in a 1953 patent2. Later development of ZN catalyst led to the production of LLDPE3. A HDPE process to make broad molecular weight distribution (MWD) resin was later developed at Phillips Chemicals Company based on the chromium oxide technology4. Lately, polyethylene (PE) catalyst development including the metallocence technologies has become more specialized aiming to improve the control of desired molecular weight and MWD and the short chain distribution (SCBD)5. These structural differences are the key to the performance of modern day PE resins in any specific applications and process conditions. The question is how one can characterize these microstructure differences. To meet this need, a polymer microstructure analysis using a hybrid 3D-GPC-TREF instrument equipped with triple-detectors is developed6. This analysis combines a 3D-GPC technique (triple-detector gel permeation chromatography), a technique that separates polymers by molecular size and is capable of measuring MWD and LCBD), with a 3D-TREF technique (triple-detector temperature rising elution fractionation), a technique that separates polymer by crystallization temperature and is capable of measuring SCBD and MW dependency of chemical composition distribution (CCD). A HYBRID 3D GPC-TREF INSTRUMENT An experimental hybrid system is built by installing a TREF add-on oven compartment to an existing Waters 2000CV GPC System with a built-in refractive index detector and viscometer. Two additional detectors are added to the system. These are the PolymerChar IR4 detector and the PDI-2040 light scattering detector with 15 and 90-degree dual-angle capability. The configuration of the instrument is described by the schematic in Figure 1. The six-port valve in the system automatically switches the solvent flow through either the GPC columns or the TREF columns at several pre-determined set times.

Hybrid 3D - GPC/TREF

TREF Column

PDI DV

RI

Waters 2000CV Column Compartment

IR

TREF Oven with Programmable

Temperature Ramping

A B

A A

B B

Option Valve Position TREF Control Injection(s)

3D - GPC B OFF 1

3D - TREF Load=A ON 1

Crystal.=B Elution=A

3D - GPC/TREF Load1=A 2*

Load2=B Elution=A

* Injections with ~3 minute offset

From 2000CV Injector 1

2 3

6 Filter

Figure 1. Configuration of the Hybrid 3D GPC-TREF System While the sample loaded in the TREF column is being cooled down in the add-on oven from 150 to 40°C during the crystallization step, the solvent flow is automatically switched into the GPC column to allow the GPC separation of the polymer sample to take place. The GPC run is complete at the end of the two and a half hour crystallization step. At which time, the solvent flow is switched again. This time the flow is directed into the TREF column to flush out the polymer from the TREF column. During this one-hour TREF elution step, the TREF oven temperature is programmed to increase linearly from 40 back to 150°C. The TREF elution is completed at the end this heating period. In this process, both GPC and TREF runs are complete in a three-and-half hour cycle. With the use of the auto-sampler capability of the Waters 2000CV GPC System, up to 24 samples can be loaded at one time and analyzed in an unattended operation, at the rate of about seven samples for every 24 hours. Figure 2 shows an example of a hybrid GPC-TREF run on a hexene ZN-LLDPE sample. The temperature profile during the cooling and the heating cycle is also recorded as shown in Figure 2.

0

200

400

600

800

1000

1200

1400

1600

1800

0 20 40 60 80 100 120 140 160 180 200Retention Time (minutes)

Cou

nts

(A>D

)

0

500

1000

1500

2000

2500

3000

3500

Wilkes IR PDI 90 degrees

TREF Column Temperature TREF Column Compartment

The Hybrid GPC-Tref Chromatogram of a ZN-LLDPE Sample

Figure 2. The Hybrid GPC-TREF Chromatogram of a Hexene ZN-LLDPE The TREF technique relies on the crystallization and re-dissolution process to separate polymers having different degrees of short chain branching (SCB). Figure 3 depicts the TREF elution profile separating SCB. The elution peak detected immediately after the flow switches back through the TREF column is caused by the soluble fraction in the sample. This is the fraction of material that has remained soluble in 40°C tri-chlorobenzene (TCB) at the end of the cooling cycle. As the temperature increases with time during this TREF elution cycle, the more branched molecules elute first, then the ones with decreasing SCB, followed by the more linear “homopolymer fractions”. The crystallization step (Figure 3) depicts the process where polymer fractions with different levels of SCB precipitate and coat the TREF packing beads during the cooling cycle. Polymer fractions coat the packing particles in layers with the most highly branched fraction precipitating out last to form the outer layer. In this picture of an “onion ring structure”, the outer layer of higher SCB will elute first in the TREF cycle. Therefore, the crystallization and heating cycles act in synergy forming and separating the polymer layers on the surface of the packed bed.

Crystallization Step

Tem

pera

ture

Increasing Branching

Polymer Dissolution & Elution

Temperature Profile

LDPELLDPE

HDPE“homo-polymer”

Waxy or HighlyBranched Polymer

Soluble Fraction

Low MeltingFraction

High MeltingFraction

Conc

entra

tion

Inert TREFPacking Particle

Figure 3: TREF Separation Mechanism: Crystallization and Dissolution It should be noted that SCBD can also be determined by the depletion of polymer from solution during the cooling cycle. A standard method based on that principle is called crystallization fractionation or CRYSTAF for short7,8,9. RESULTS There exists close synergism between GPC and TREF. This is much like the synergism that one finds between two of the most used laboratory tests: the density and melt index (MI) tests. In many ways, TREF is more related to density and product properties, while GPC is more related to MI and flow properties. There is a wealth of polymer structural information by combining 3D-TREF with 3D-GPC results. A “polymer microstructure plot” is created which consists of sample comparative overlay curves of both 3D-GPC and 3D-TREF in one graphic display. An example of such a plot is shown as Figure 4, which gives an in-depth comparison of the microstructure differences between two LDPE samples. This overlay approach of using all six detector signals provides a very effective tool for detecting subtle differences between good versus bad production lots, for comparing competitive resins, and for fine tuning resin properties for specific applications by changing catalyst and reactor conditions. A few obvious rules for interpreting the microstructure results are indicated in Figure 4. The arrows marked in the plot illustrate the trend of changing LCB, MI, MW, molecular size, SCB, and density. For example, the light scattering signal in this 3D-GPC plot shows that there is much more LCB for the sample labeled LDPE1, which is an autoclave product. Also, for samples of similar structure, increasing intrinsic viscosity is generally indicative of decreasing MI. On the TREF side of the plot, we see that the short chain branching is narrowly distributed in both of these samples. The sample labeled LDPE1 has much more short chain branching (lower elution temperature) than the NBS 1476 reference sample of a tubular LDPE resin.

Figure 4: Microstructure Plot Comparison of LDPE Samples

3D-TREF Elution Temperature (Celsius)TriSEC Elution Volume (mL)

Det

ecto

r Sig

nal (

mV

- Sca

led)

Light Scattering(Molecular Weight x

Concentration)

Viscometer(Intrinsic viscosity x

Concentration)

Refractometer(Concentration)

35 11515 30

Light Scattering(Molecular Weight x

Concentration)

Viscometer(Intrinsic viscosity x

Concentration)

Infra-Red(Concentration)

IncreasingLCB

HigherMI

TriSEC 3D-TREF

LDPE1: D=0.917, MI=12

NBS 1476: D=0.931, MI=1.19

Increasing Molecular Size Increasing SCB, Decreasing Density

3D-G PC

APPLICATION EXAMPLES MW-Dependency of SCB Distribution in LLDPE The 3D TREF chromatogram for a hexene ZN-LLDPE is shown in Figure 5. From the relative peak height of the LS, viscosity and IR detector signals, we can learn more about the SCB features of this sample. First, we can tell that the soluble fraction in this sample is made up with the highly branched polymers, not low-MW wax or oligomers. This conclusion is reached because of the existence of the high LS and viscosity signal associated with this soluble material. Secondly, we can tell that the hexene co-monomers are more concentrated in the low-MW part of the polymer MWD. This conclusion is reached by observing the relatively higher LS signal in the high-melting “homopolymer” peak, in comparison to the lower-melting materials of higher SCB from more hexene incorporation.

Figure 5. The 3D-TREF elution curve for a Hexene ZN-LLDPE Sample. A reverse MW-dependency on SCB distribution is seen in some metallocene-based LLDPE (mLLDPE) samples. An example of which is shown in Figure 6. For this sample, we see a higher LS signal for the more branched low-melting component. This clearly indicates that the hexene co-monomers are more concentrated in the higher MW portion of the polymer MWD. In this sample, there is little soluble fraction of polymeric nature, which is quite contrary to the Ziegler-Natta samples. These are the structural features that are considered highly desirable for polyethylene products of good optical and physical properties.

Figure 6. The 3D TREF elution curve for a Hexene mLLDPE Sample

38.93 46.13 53.33 60.53 67.73 74.94 82.14 89.34 96.54 103.74 110.94

Rel

ativ

e D

etec

tor R

espo

nse

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

Retention Temperature (Celcius)

Raw Chromatogram

IR Detector

Viscometer

Light Scattering

3DTref of ZN-LLD - Higher SCB in Lower MW Region

HighlyBranchedPolymericSolubleFraction

Branched Low-melting Components

Homo-polymerFraction

46.88 53.28 59.68 66.07 72.47 78.86 85.26 91.65 98.05 104.44 110.84

Rel

ativ

e D

etec

tor R

espo

nse

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

Retention Temperature (Celcius)

Raw Chromatogram

IR Detector

Viscometer

Light Scattering 90deg

3DTref of m-LLD - Higher SCB in Higher MW Region

Polymer Gel Problem in HDPE Film Several observations can be made based on the polymer microstructure results shown in Figure 7. The 3D-GPC curves at the left show that the so-called “gel” particle is a material of much higher MW than the bulk film matrix material. But, this material is not what one would normally expect of a highly branched gel material. It is basically made up of very high MW and high-melting material. The 3D-TREF results on the right side of the plot clearly support such conclusions. This study would be very difficult with any other analyses because of the difficulty of collecting enough “gel” particles for testing. Only a milligram gel particle is needed for 3D-GPC-TREF analyses.

Figure 7. Polymer Microstructure of “Gel” Particles in HDPE. HIGH-PRECISION LCB INDICES: gpcBR and trefBR The effect of LCB can be easily detected in the visual inspection of the 3D-GPC or 3D-TREF curves. In order to catch LCB information more quantitatively and precisely, we have introduced two LCB indices that are described below. The formulation of these new LCB indices is created in a way that they can be compared with the other LCB indices used in the rheological tests. We have recently introduced a novel branching index referred to as gpcBR10. This branching index takes advantage of the four most precise parameters that can be calculated by 3D-GPC, i.e., the conventional Mw and Mv versus the light scattering Mw and viscometer measured intrinsic viscosity values.

The subscript LS refers to light scattering, the subscript LIN refers to the values obtained from conventional GPC analysis assuming linear polymer, and parameter α is the Mark-Houwink exponent for polyethylene. The theoretical value of gpcBR is zero for linear polyethylene. It can range to as high as 4 for typical LDPE resins. To observe LCB across a 3D-TREF elution curve, we also introduced the trefBR index.

A summary of existing LCB methods is shown in the table below.

01354AG HDPE Film Control01354BG "Gel" or "Un-melt" ?

3D-GPC "Gel" or "Un-melt" in HDPE Film

3 3.5 4 4.5 5 5.5 6 6.5 7

Log MW (conventional Calibration)

LS = Mw x Conc.

IR = Conc.

DP = IV x Conc.

01354AG HDPE Film Control01354BG "Gel" or "Un-melt" ?

3D-TREF "Gel" or "Un-melt" in HDPE Film

35 45 55 65 75 85 95 105Temperature (C)

IR = Conc.

LS = Mw x Conc

DP = IV x Conc.

The high-MW material in question elutes at high temperature, with no significant branching is indicative of “Un-melt”, not “gel” or cross-linking

3D-GPC shows nearly linear high-MW material

LS = Mw x Conc.

"Gel or Un-melt ? " "Gel or Un-melt ? "

[ ][ ] 1 -

MM

gpcBRWLIN

WLS

⎪⎭

⎪⎬⎫

⎪⎩

⎪⎨⎧

×⎟⎟⎠

⎞⎜⎜⎝

⎛=

LS

LIN

ηη

α

[ ]nepolyethylefor0.00374K0.73,α:where

1*

≈≈

−⎥⎦

⎤⎢⎣

⎡≡

GPCV

LSMwKtrefBRη

α

CONCLUSIONS We have found that the combination of 3D-GPC and 3D-TREF forms an invaluable pair of analytical tools that complement each other well in studying many areas of polymer interests where the understanding of polymer structure-property relationships is of central importance. Not only is the combination of these two techniques useful in understanding the desired microstructure for a given resin, the combination of the techniques finds great utility in analyzing blended components. We believe that a strong polymer microstructure program is the corner stone of successful polymer characterization support in today’s challenging polyolefin industry. ACKNOWLEDGEMENT The author is indebted to the other contributors to the material reported in this paper: Tia Kuhlman, Clay Enos, Jean Merrick-Mack, Gary Cheney, Mark Reinking, Sameer Mehta, Chun Lee, Ken Klaber, Sebastian Joseph, Dan Ward, and the Lyondell Cincinnati Technology Center Management. REFERENCES 1 Fawcett, E. W., Gibson, R. O., Perrin, M. W., Patton, J. G., Williams, E. G., B Patent 471,590, Sept. 6, (1937 ). 2 Ziegler, K., Ger Patent 878,560 (1953). 3 Boor, J., “Ziegler-Natta Catalysts and Polymerizations”, New York: Academic Press, (1979). 4 McDaniel, M. P., and Johnson, M. M., Macromolecules, 20: 773 (1987). 5 Kaminsky, W., Macromol. Chem. Phys., 197:3907 (1996). 6 Yau, W., and Gillespie, Polymer, Vol. 42 pp.8947-8958 (2001). 7 Monrabal, B., J. Appl. Polym. Sci. 52, 491 (1994). 8 Soares, J. B. P., Monrabal, B., Nieto, J., and Blanco, J., Macromol. Chem. Phys. 199, 1917-1926 (1998). 9 Anantawaraskul, S., Soares, J. B. P., and Wood-Adams, P. M., J. Polym. Sci., Polymer Physics, Vol. 41, 1762-1778 (2003). 10 Enos, C. and Yau, W., 2003 International GPC Symposium, proceedings in print.

LCB Method Development Methods Zero-

shear Melt

Viscosity

Ubbelohde Intrinsic Viscosity

Mw by conventional

GPC

Mw by GPC-LS

IV by GPC-

viscometry

Remarks And

Indices

Jansen and

Colby Yes - Yes

Shroff and Mavridis

Yes Yes LCBI and ER

Drott and Mendelson

Yes Yes Yes g’ and λ

MH and g’-index

Yes Yes Yes g’

Yau and

Enos Yes Yes Yes gpc-BR

Yau and Enos

Tref-LS Tref-viscometry

Tref-BR

Others?

Note: Unlike the rheology LCB, the gpc-BR approach can be developed to provide LCB distribution across the GPC-MWD curve; similarly the tref-BR approach can be used to provide the presence of LCB across the TREF-SCBD curve.

1

1

2

Today’s Challenges in Polyofefins …

Polyolefin µ-Structure CharacterizationUsing 3D-GPC-TREF

Introduction: The 3D-GPC-TREF techniques

Examples: R&D Support and Problem Solving

The LCB Issues

Future Challenges and Opportunities

3

Polyethylene MW and Branching Structures• Ethylene homopolymers (HDPE) have the most tightly

packed chains and the highest density (Produced from ethylene monomer only).

• Addition of copolymer (butene, hexene, or octene) introduces short branches that do not pack well and result in lower densities (co-polymer HDPE, LLDPE).

• High-pressure LDPE process yields a polymer with both short & long-chain branching. Chains do not pack well, resulting in low density.

2

4

Hybrid 3D-GPC/TREF

TREF Column

PDI

DV

RI

Waters 2000CV Column Compartment

IR

TREF Oven with Programmable

Temperature Ramping

A

B

A

A

B B

Option Valve Position TREF Control Injection(s)

3D-GPC B OFF 1

3D-TREF Load=A ON 1

Crystal.=B

Elution=A

3D-GPC/TREF Load1=A 2*

Load2=B

Elution=A

* Injections with ~3 minute offset

From 2000CVInjector 1

2 3

6Filter

5

Polymer Separation in Automated TREF

Crystallization Step

Tem

pera

ture

Increasing Branching

Polymer Dissolution & Elution

Temperature Profile

(TREF = Temperature Rising Elution Fractionation)

LDPELLDPE

HDPE“homo-polymer”

Waxy or HighlyBranched Polymer

Soluble Fraction

Low MeltingFraction

High MeltingFraction

Conc

entra

tion

Inert TREFPacking Particle

6

0

200

400

600

800

1000

1200

1400

1600

1800

0 20 40 60 80 100 120 140 160 180 200Retention Time (minutes)

Cou

nts

(A>D

)

0

500

1000

1500

2000

2500

3000

3500

Wilkes IR PDI 90 degrees

TREF Column Temperature TREF Column Compartment

The Hybrid GPC-Tref Chromatogram of a ZN-LLDPE Sample

Temperature Profile

GPC Profile

TREF Profile

GPC Elution Followed by TREF Fractionation in Single Experiment

3

7

Synergisms within GPC & TREF Microstructure Tests

ZN- ButeneZN- Hexenem-LLDPE

GPC TREF

Molecular Weight Short Chain Branching

Conc

entra

tion

Conc

entra

tion

8

9

3D-GPC of LDPE

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

12 14 16 18 20 22 24 26 28 30

GPC Elution Volume (ml)

Det

ecto

r sig

nals

(mv)

Sample G (LDPE-1, d=0.917,MI=12)

Sample H (LDPE-2 NIST1476, d=0.931, MI=1.19)

DP Viscosity = IV * C

15 Degree LS = M * C

IR Conc. Signal = C

3D-Tref of LDPE

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

Tref Elution Temperature (C)

Det

ecto

r sig

nals

(mv)

Sample G (LDPE-1,d=0.917, MI=12)

Sample H (LDPE-2 NIST1476, d=0.931, MI=1.19)

DP Viscosity = IV * C

15 Degree LS = M * C

IR Conc. Signal = C

Increasing MolecularSize

Increasing SCB

Decreasing Polymer density

LCB

Higher MW

Lower MI

A Simplistic View of Interpreting Hybrid TriSEC-3DTref

All SolubleFraction

PolymericSoluble Fraction

4

10

Today’s Challenges in Polyofefins …

Application Examples of Polymer μ-Structure Characterization

Catalyst and Pilot Plant R&D Support

Product Development and Tech Service Problem Solving

11

NA831G Tubular LDPE, MI=9, density=0.919NA214G Autoclave LDPE, MI=10, density=0.918NA219G Autoclave LDPE, MI=10, density=0.923

3D-GPC Tubular vs Auto-Clave LDPE

3 3.5 4 4.5 5 5.5 6 6.5 7

Log MW (conventional Calibration)

LS = Mw x Conc.

IR = Conc.

DP = IV x Conc.

NA831T Tubular LDPE, MI=9, density=0.919NA214BT Autoclave LDPE, MI=10, density=0.918NA219T Autoclave LDPE, MI=10, density=0.923

IR-TREF Tubular vs Autoclave LDPE

35 45 55 65 75

Temperature (C)

IR = Conc.

Tubular LDPE has much less LCB than Autoclave LDPE

Tubular LDPE has higher-temperature high-melting peak, but with higher level of low-MW soluble fraction.

3D-GPC Tubular vs Autoclave LDPE

12

0001G-1 Original Peroxide0001G-2 Original Peroxide (Repeat)0002T-1 Modified Persoxide0002T-2 Modified Persoxide (Repeat)

3D-TREF Effect of Peroxide on LDPE

35 45 55 65 75 85Tem pera ture (C)

IR = Conc.

LS = Mw x Conc

DP = IV x Conc.

0001G-1 Original Peroxide0001G-2 Original Peroxide (Repeat)0002G-1 Modified Persoxide0002G-2 Modified Persoxide (Repeat)

3D-GPC Effect of Peroxide on LDPE

3 3.5 4 4.5 5 5.5 6 6.5 7

Log MW (conventiona l Ca libra tion)

LS = Mw x Conc.

IR = Conc.

DP = IV x Conc.

High precision results are needed to detect subtle but import differences

Less LCB

Higher density

0002-G-1 Modified Peroxide0002-G-2 Modified Peroxide (Repeat)

0002-T-1 Modified Peroxide0002-T-2 Modified Peroxide (Repeat)

LS = Mw x Conc.

5

13

50.92 58 .25 65 .57 72 .90 80 .23 87 .56 94 .88 102 .21 109 .54 116 .87 124 .20

Rel

ativ

e D

etec

tor R

espo

nse

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

Retention Temperature (Celc ius)

Raw Chromatogram

IR D e t e c t o r

V i s c o m e t e r

Li g h t S c a t t e r i n g 9 0 d e g

3D-Tref of ZN-LLD with usual MW-SCB Dependency -Higher SCB components are of Lower MW

High SCB, butlower MW

14

46.88 53.28 59.68 66.07 72.47 78.86 85.26 91.65 98.05 104.44 110.84

Rel

ativ

e D

etec

tor R

espo

nse

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

Retention Temperature (Celcius)

Raw Chromatogram

IR Detector

Viscometer

Light Scattering 90deg

3D-Tref of m-LLD with Reverse MW-SCB Dependency -Higher SCB components are of Higher MW

High SCB, and higher MW

15

49.51 57.82 66.13 74.43 82.74 91.05 99.35 107.66 115.97 124.27 132.58

Rel

ativ

e D

etec

tor R

espo

nse

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

Retention Temperature (Celcius)

Raw Chromatogram

IR D e t e c t o r

V is c o me t e r

Lig ht S c at t e ring 9 0 d e g

3D-TREF (Company-A-xxxxx) 3D- TREF (Company-B – yyyyy)

46.88 53.28 59.68 66.07 72.47 78.86 85.26 91.65 98.05 104.44 110.84

Rel

ativ

e D

etec

tor R

espo

nse

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

Retention Temperature (Celcius)

Raw Chromatogram

IR Detector

Viscometer

Light Scattering 90deg

SM No.Sample ID

Lot No.

A04-02924Company-Axxxxx

A01-16295Company-B

yyyyy

~ 1.76 1.19

0.72 1.41 2.170.66 0.24 0.15

75,600

0.15

63,000 107,000 174,00013.7% 67% 20%

Wt. % Mw IV g/dl Wt. % Mw IV g/dl Wt. % Mw IV g/dl

2.1%~

58%135,900

0.19

40%

Company-A-xxxxx and Company-B-yyyyy (4T0511)Zone-2 Low-Melts

40°C < Temp < 85°CZone-3 High-Melts

85°C < Temp < 110°CTemp @ 40°CZone-1 Solubles Ratio Zone2 / Zone3

trefBR > 0.7 ?

Wt. % Mw IV g/dl

1.481.80

1.48no

3.430.61

0.65no

SM No.Sample ID

Lot No.

A04-02924Company-Axxxxx

A01-16295Company-B

yyyyy

~ 1.76 1.19

0.72 1.41 2.170.66 0.24 0.15

75,600

0.15

63,000 107,000 174,00013.7% 67% 20%

Wt. % Mw IV g/dl Wt. % Mw IV g/dl Wt. % Mw IV g/dl

2.1%~

58%135,900

0.19

40%

Company-A-xxxxx and Company-B-yyyyy (4T0511)Zone-2 Low-Melts

40°C < Temp < 85°CZone-3 High-Melts

85°C < Temp < 110°CTemp @ 40°CZone-1 Solubles Ratio Zone2 / Zone3

trefBR > 0.7 ?

Wt. % Mw IV g/dl

1.481.80

1.48no

3.430.61

0.65no

SM No.Sample ID

Lot No.

A04-02924Company-Axxxxx

A01-16295Company-B

yyyyy

~ 1.76 1.19

0.72 1.41 2.170.66 0.24 0.15

75,600

0.15

63,000 107,000 174,00013.7% 67% 20%

Wt. % Mw IV g/dl Wt. % Mw IV g/dl Wt. % Mw IV g/dl

2.1%~

58%135,900

0.19

40%

Company-A-xxxxx and Company-B-yyyyy (4T0511)Zone-2 Low-Melts

40°C < Temp < 85°CZone-3 High-Melts

85°C < Temp < 110°CTemp @ 40°CZone-1 Solubles Ratio Zone2 / Zone3

trefBR > 0.7 ?

Wt. % Mw IV g/dl

1.481.80

1.48no

3.430.61

0.65no

6

16

01354AG HDPE Film Control01354BG "Gel" or "Un-melt" ?

3D-GPC "Gel" or "Un-melt" in HDPE Film

3 3.5 4 4.5 5 5.5 6 6.5 7

Log MW (conventional Calibration)

LS = Mw x Conc.

IR = Conc.

DP = IV x Conc.

01354AG HDPE Film Control01354BG "Gel" or "Un-melt" ?

3D-TREF "Gel" or "Un-melt" in HDPE Film

35 45 55 65 75 85 95 105Temperature (C)

IR = Conc.

LS = Mw x Conc

DP = IV x Conc.

The high-MW material in question elutes at high temperature, with no significant branching is indicative of “Un-melt”, not “gel” or cross-linking

3D-GPC shows nearly linear high-MW material

LS = Mw x Conc.

"Gel or Un-melt ? " "Gel or Un-melt ? "

17

18

Today’s Challenges in Polyofefins …

Detecting Long Chain Branching (LCB)LCB of interest to processing and end-use

properties has much longer than 6-8 carbon side chains; they are not easily measurable by NMRLCB of interest can be detected by rheology and

3d-GPC-TREF most of time, but not always…o LCB at the very high MW end of high-MW Cr-based pipe resins – detectable by rheology, but not by 3D-GPC-TREFo For some cases where LCB is not at the high MW end – detectable by 3D-GPC-TREF, but not by rheology

7

19

LCB Method Development Methods Zero-

shear Melt

Viscosity

Ubbelohde Intrinsic Viscosity

Mw by conventional

GPC

Mw by GPC-LS

IV by GPC-

viscometry

Remarks And

Indices

Jansen and

Colby Yes - Yes

Shroff and Mavridis

Yes Yes LCBI and ER

Drott and Mendelson

Yes Yes Yes g’ and λ

MH and g’-index

Yes Yes Yes g’

Yau and

Enos Yes Yes Yes gpc-BR

Yau and Enos

Tref-LS Tref-viscometry

Tref-BR

Others?

Note: Unlike the rheology LCB, the gpc-BR approach can be developed to provide LCB distribution across the GPC-MWD curve; similarly the tref-BR approach can be used to provide the presence of LCB across the TREF-SCBD curve.

20

-0.5

-0.3

-0.1

0.1

0.3

0.5

0.7

0.9

1.1

1.3

1.5

4.00 4.50 5.00 5.50 6.00 6.50

Log Mw

Log

IV

LinearL5845NA220NA220/L5845 7.0 %NA220/L5845 13.8%NA220/L5845 24.7%NA220/L5845 49.4%

Mark-Houwink Plot (Mixtures of NA220 in L5845)

The addition of LCB by adding LDPE to high-MW HDPE is not easily detected by rheology.

High-MW end of the HDPE sample

LinearHDPE of Broad MWDLDPELD in HDPE 7.0 %LD in HDPE 13.8%LD in HDPE 24.7%LD in HDPE 49.4%

Mark-Houwink Plot (Mixtures of LDPE in HDPE )

LinearHDPE of Broad MWDLDPELD in HDPE 7.0 %LD in HDPE 13.8%LD in HDPE 24.7%LD in HDPE 49.4%

Mark-Houwink Plot (Mixtures of LDPE in HDPE )

21

68ave HDPE (density = 0.952)70ave HDPE (density =0.950)NA831G LDPE (density = 0.919)

3D-GPC (LCB in LDPE) vs (LCB in HDPE)

3 4 5 6 7

Log MW (conventional Calibration)

LS = Mw x Conc.

IR = Conc.

DP = IV x Conc.

68net HDPE (density = 0.952)70net HDPE (density =0.950)01258net LDPE (density = 0.919)

3D-TREF (LCB in LDPE) vs (LCB in HDPE)

35 45 55 65 75 85 95 105Temperature (C)

IR = Conc.

LS = Mw x Conc

DP = IV x Conc.

LCB in both samples

LCB in HDPE

LDPE

31ave

8

22

Blend of HiD (NBS1484) and LDPE-a Sample

0

1

2

3

20 30 40 50 60 70 80 90 100 110 120 130 140

Elution Temperature before offset correction

Det

ecto

r sig

nal (

mv)

NBS1484-LDPE

LS-90-degree -10

0

10

20

30

50 140

Hea

t Flo

w (m

v)

NBS1484+LDPE Blend

solutionmeltingm

meltingm SDeltaSDelta

HDeltaTrefTSDelta

HDeltaDSCT][&][

:)(][

:)(+= =

SYNERGISM OF TREF-LS AND DSCA Blend of LDPE-1 and HDPE (NIST 1484)

LS (M*C)

IR (C)

Delta-H*C86.8C

116.6C

DSC SCAN

23

Today’s Challenges in Polyofefins …

Polymer Science Program to Study Structure Property Relationships

Close the gap between GPC and Rheology

Explore the synergies between TREF and DSC

Build links to crystalline morphology and end-use properties.

24

9

25