EoW May 2008

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The example in Tables 1-3 helps demonstrate that improved compound performance, such as improved physical properties and low temperature performance, can be achieved by using the correct elastomer matrix with optimised chain architecture to allow higher loading of the ingredients to further balance the compound performance and potentially positively impact the compound economics. 6. Conclusions Elastomers can participate in a broad range of applications, including thermoplastic or thermoset systems, such as jacketing, insulation, bedding, low-smoke zero halogen, and low-voltage insulation. Higher levels of filler can be incorporated into elastomers to broaden their compound performance attributes to make them especially suited for demanding environments. The chain architecture of the elastomer is important to determine how and how much of the various ingredients can be or should be used in the compound to achieve the desired end use performance. Cross-linked elastomer compounds have excellent heat and oil resistance, and the cure rate can be conveniently adjusted by diene levels. Most of the EPRs or EPDMs are suited for applications demanding good mechanical properties due to its high molecular weight, but EB or EO is popular as rheology modifier due to its relative lower viscosity. The presence of chlorine in chlorinated polyethylene further improves its chemical, oil, and flame resistance over that of non-chlorine containing ethylene elastomer. As a result, simple changes in structure architectural parameters in ethylene containing elastomer can greatly extend the typical polyethylene cable performance attributes for broader applications. n

'Normal Loading'

'High Loading'

CM-a 1.607

CM-a 1.648

CM-d CM-d/EO-b

Density

1.648

1.622

CM-a CM-d EO-b

100

100

--

--

-- --

-- --

100

85 15

--

Trifunctional acrylic ester (co-agent) a,a’-bis(t-butyl peroxy)

5 5

5 5

5 5

5

6.5

diisopropyl benzene, 40% active N-550 Carbon black

35

--

--

--

N-774 Carbon black Calcium carbonate

--

80

80

80

150

200

200

200

DINP

38

60 1.5

60 1.5

60 1.5

Paraffin wax

2 5

Magnesium oxide

5

5

5

Total phr:

340

456.5

456.5

458

Table 1 ▲ ▲ : Flexible cord jacket recipes

'Normal Loading'

'High Loading'

CM-a

CM-a CM-d CM-a/EO-b

Processing Characteristics

Mooney Scorch at 121°C, Small Rotor Minimum, MU

28.5 >25 >25

23.2 >25 >25

39.5 >25 >25

31.5 24.2 24.7

t3, mins t5, mins

RPA (Rubber Processability Analyzer) at 110°C, 10% Strain Viscosity at 150 rad/s, Pa-s

4577

3842

5282

4764

Wire Line Extrusion, 38.1 mm Extruder, 15:1 L:D, ~ 110°C) Extruder Pressure, MPa

27

23

29

25

Curing Characteristics

Oscillating Disk Rheometer at 200ºC for 6 mins Minimum, dN-m

11.2 80.7 69.5

6.6

15.2 75.8 60.6

13.3 82.1 68.8

Maximum, dN-m delta Torque, dN-m

56.3 49.7

7. References

t90, mins

1.7

1.8

1.9

1.8

Table 2 ▲ ▲ : Processing and curing characteristics Table 3 ▼ ▼ : Physical properties

[1] Polymeric Materials Encyclopedia, Volume 2/C, CRC Press, 1996, Editor-in-Chief J C Salamone, chapter on“Chlorinated Polyethylene”, G R Marchand [2] Classification System for Rubber Material (SAE J200), Society of Automotive Engineers, Warrendale, Pa, 2000 [3] Standard Test Method for Rubber Property–Effect of Liquids (ASTM D471-79) 1979

'Normal Loading'

'High Loading'

CM-a

CM-a CM-d CM-d/EO-b

Original Physicals * Stress at 100% Elongation, MPa

3.4 9.2

3.5 7.6

2.6 9.8

4.6 9.7

Ultimate Tensile, MPa Elongation at Break, % IRM 902/18 hr at 121°C* Tensile Retention, % Elongation Retention, %

514

518

350

306

87 91

90 58

94 86

96 89

Air Oven Aging -- 10 Days at 110°C Tensile Retention, %

The Dow Chemical Company 1 Riverview Drive Somerset, NJ 08873, USA Tel : +1 732 271 2021 Website : www.dow.com Email : leedc@dow.com

93 80

108

98 79

92 75

Elongation Retention, %

52

LowTemperature Brittleness, °C**

-27.5

-29.5 -32.5

-35.5

*14 AWG (1.63mm dia) aluminium wire/0.76mm jacket/cured 2 min in 1.72 MPa steam **Slab/cured 2 min at 200°C

80

EuroWire – May 2008