Influence of Branch Influence of Branch Content on the Content on the

Mechanical Properties Mechanical Properties of metallocene of metallocene

LLDPEsLLDPEsAshraful Islam, Ibnelwaleed A. Ashraful Islam, Ibnelwaleed A.

HusseinHussein Department of Chemical EngineeringDepartment of Chemical Engineering

PPS 21PPS 21stst Annual Meeting, Leipzig, Annual Meeting, Leipzig, GermanyGermany

June 19-23, 2005 June 19-23, 2005

IntroductionIntroduction Literature ReviewLiterature Review ObjectivesObjectives Experimental workExperimental work Results & DiscussionsResults & Discussions

OUTLINE

HDPE LDPE

m-LLDPE

Schematic representation of the different classes of PE

ZN-LLDPE

Morphology of polyethylene

LITERATURE REVIEW

Authors Authors [Year][Year]

CommentsComments

Mandelkern & Mandelkern & Maxfield [1979]Maxfield [1979]

Studied the morphology of ZN LDPEs for two different Studied the morphology of ZN LDPEs for two different extreme crystallization modes. The thermodynamic extreme crystallization modes. The thermodynamic properties of LDPE primarily governed by BC and not properties of LDPE primarily governed by BC and not much dependent on molecular weight.much dependent on molecular weight.

Popli & Popli & Mandelkern Mandelkern [1987] [1987]

Studied mechanical properties of HDPE & LDPEs. Studied mechanical properties of HDPE & LDPEs. LDPEs showed lower yield stress compared to HDPEs. A LDPEs showed lower yield stress compared to HDPEs. A nonlinear relationship was found for Young’s modulus as nonlinear relationship was found for Young’s modulus as function of BC for ZN-LDPEs. Ultimate properties were function of BC for ZN-LDPEs. Ultimate properties were not strongly influenced by BC. not strongly influenced by BC.

Authors Authors [Year][Year]

CommentsComments

Bensason et al. Bensason et al. [1996][1996]

Classified Ethylene-Octene copolymers based on BC. Classified Ethylene-Octene copolymers based on BC.

LITERATURE REVIEW (Cont’d)

LITERATURE REVIEW (Cont’d)

Authors Authors [Year][Year]

CommentsComments

Simanke et al Simanke et al [1999] [1999]

Reported low strain properties of m-LLDPEs. They failed Reported low strain properties of m-LLDPEs. They failed to report high strain properties due to the sample to report high strain properties due to the sample slippage in the grips.slippage in the grips.

Walker et al Walker et al [2003] [2003]

DSC analysis of m-LLDPEs showed a progressive DSC analysis of m-LLDPEs showed a progressive increase in Tincrease in Tmm with decreasing BC. The results also with decreasing BC. The results also

showed that the ZN-LLDPEs have higher melting showed that the ZN-LLDPEs have higher melting temperature than the m-LLDPEs. temperature than the m-LLDPEs.

LITERATURE REVIEW (Cont’d)

Summary:

1. Studied thermal and mechanical properties of different catagories of ZN HDPE, LDPE and LLDPEs.

2. Investigated the effect of Mw and thermal treatment on the various thermal transitions.

3. Examined the effect of comonomer type and BC on the different thermal transitions of ZN-LLDPEs.

4.Compared the final properties of traditional ZN-LLDPE with m-LLDPE.

5.Studied the influence of BC on low strain properties of m-LLDPEs with BC less than 20 CH3/1000C.

Table 01: Polymer Characterization

ResinsDensity,

g/cm3

Mw,

Kg/molMI,

g/10minMWD BC

(CH3/1000C)

m-EH12 0.918 94 2.5 1.40 12.02

m-EH15 0.912 102 1.20 2.14 14.5

m-EH18 0.900 108 1.20 1.83 18.02

m-EH20 0.902 95 2.0 2.06 19.74

m-EH24 0.895 92 2.20 1.85 32.60

m-EH32 0.883 97 2.20 2.02 32.17

ZN-EH17 0.917 80 2.80 8.40 16.71

Resin

Carver Press

Thin Sheet

Pneumatic Punch CutterDog-bone

Instron Machine

Experimental Steps (Mechanical)

Resin Aluminum Pans

Press

Modulated DSCLNCS

Experimental Steps (Thermal)

0

5

10

15

20

25

30

35

40

45

0 200 400 600 800 1000 1200 1400

Engineering Strain (%)

Engi

neer

ing

Stre

ss (M

Pa)

m-EH12

m-EH15

m-EH18

m-EH20

m-EH24

m-EH32

BC = 12.0

14.4

19.7 23.6

18.0

32.2

Figure 03: Stress/Strain curves for EH m-LLDPEs with different BCs.

Table 2: Selected thermal properties of ethylene/-olefins copolymers

ResinBC

(CH3/1000C)

Melting Peak (oC)DSC Crystallinity Values

(%)

Before After Before After

m-EH1212.02 115.2 114.7 40.3 41.6

m-EH1514.50 105.7 103.0 34.9 36.0

m-EH1818.02 95.7 99.6 28.9 29.0

m-EH2019.74 45.1, 88.3 45.4, 94.7 31.1 31.5

m-EH2423.60 47.2, 90.3 43.2, 92.6 28.4 29.6

m-EH3232.17 46.4, 73.2 44.7, 80.0 22.6 25.2

Figure 04: Avrami plot for EH m-LLDPEs (Strain rate 4.92 min-1)Figure 04: Avrami plot for EH m-LLDPEs (Strain rate 4.92 min-1)

Resins m-EH12

m-EH15

m-EH18

m-EH20

m-EH24

m-EH32

Avrami Exponent (n)

0.65 1.34 1.31 1.44 1.35 1.34

Crystallization Rate Constant (k)

1.01 0.95 0.91 0.96 0.89 0.81

-10

-8

-6

-4

-2

0

2

-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3

lnt

ln(-

ln(1

-Xt)) m-EH12

m-EH15m-EH18

m-EH20m-EH24

m-EH32

Figure 05: Yield Phenomena at crosshead speed of 125 mm/minFigure 05: Yield Phenomena at crosshead speed of 125 mm/min

0

2

4

6

8

10

12

0 20 40 60 80 100 120 140 160 180 200

Engineering Strain (%)

Engin

eerin

g St

ress

(MPa

)

m-EH12

m-EH15

m-EH18

m-EH20

m-EH24

m-EH32

BC = 12.0

14.4

19.7

18.0

23.6

32.2

Figure 06: Young’s modulus as a function of BC (crosshead speed 125 Figure 06: Young’s modulus as a function of BC (crosshead speed 125 mm/min)mm/min)

Y= 22621 BC-1.8644

R2 = 0.9846

0

50

100

150

200

250

0 5 10 15 20 25 30 35BC (CH3/1000C)

Youn

g's

Mod

ulus

m-EH

ZN-EH

Figure 07: Elongation at break as function of BC (crosshead speed 125 Figure 07: Elongation at break as function of BC (crosshead speed 125 mm/min)mm/min)

0

200

400

600

800

1000

1200

1400

1600

0 5 10 15 20 25 30 35 40 45Branch Content (CH3/1000C)

Elo

ngat

ion

at B

reak

(%)

m-EH

ZN-EH

Figure 08: Ultimate tensile strength as function of BC (crosshead speed Figure 08: Ultimate tensile strength as function of BC (crosshead speed 125 mm/min).125 mm/min).

0

5

10

15

20

25

30

35

40

45

0 5 10 15 20 25 30 35 40 45Branch Content (CH3/1000C)

Ultim

ate

tens

ile S

treng

th (M

Pa)

m-EH

ZN-EH

Acknowledgements:Acknowledgements:

King Abdul Aziz City for Science and Technology (KACST) for financial support

KFUPM ExxonMobil, Belgium for

providing free samples

ThanksThanks