EPDM Rubber

23/03/15 EPDM rubber - Wikipedia, the free enc clopedia

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A roll of EPDM foil, used

for waterproofing roofs

EPDM rubberFrom Wikipedia, the free encyclopedia

EPDM rubber (eth lene prop lene diene monomer (M-class) rubber),[1][2][3] a type of synthetic rubber, isan elastomer characterized by a wide range of applications. The M refers to its classification in ASTM standard D-1418; the M class includes rubbers having a saturated chain of the polymethylene type. Dienes currently used in themanufacture of EPDM rubbers are dicyclopentadiene (DCPD), ethylidene norbornene (ENB), and vinylnorbornene (VNB). EPDM rubber is closely related to ethylene propylene rubber (ethylene propylene rubber is acopolymer of ethylene and propylene, whereas EPDM rubber is a terpolymer of ethylene, propylene, and a diene-component).

The ethylene content is around 45% to 85%. The higher the ethylene content, thehigher the loading possibilities of the polymer, better mixing, and extrusion. Peroxidecuring these polymers gives a higher crosslink density compared with theiramorphous counterpart. The amorphous polymer is also excellent in processing. Thisis very much influenced by their molecular structure. The dienes, typically comprisingfrom 2.5% to 12% by weight of the composition, serve as cross-links when curingwith sulphur and resin; with peroxide cures, the diene (or third monomer) functions asa coagent, which provides resistance to unwanted tackiness, creep, or flow duringend use.

Properties

EPDM exhibits satisfactory compatibility with fireproof hydraulic fluids, ketones, hotand cold water, and alkalis and exhibits unsatisfactory compatibility with most oils,gasoline, kerosene, aromatic and aliphatic hydrocarbons, halogenated solvents, and concentrated acids.

The main properties of EPDM are its outstanding heat, ozone, and weather resistance. The resistance to polarsubstances and steam are also good. It has excellent electrical insulating properties. It has good resistance toketones, ordinary diluted acids, and alkalines.

Typical properties of EPDM vulcanizates are given below. EPDM can be compounded to meet specific propertiesto a limit, depending first on the EPDM polymers available, then the processing and curing method(s) employed.EPDMs are available in a range of molecular weights (indicated in terms of Mooney viscosity ML(1+4) at 125 C),varying levels of ethylene, third monomer, and oil content.

Mechanical properties of EPDM

Propert Value

Appearance

Hardness, Shore A 4090

Tensile failure stress, ultimate 25 MPa

Elongation after fracture in % 300%

DensityCan be compounded from 0.90 to >2.00 g/cm3

Thermal properties of EPDM



An EPDM rubber roof

Thermal properties of EPDM

Propert Value

Coefficient of thermal expansion, linear[4] 160 m/m K

Maximum service temperature[5] 150 C

Minimum service temperature[5] 50 C

Glass transition temperature 54 C

Uses

EPDM rubber is used in seals (for example, it is used in cold-room doors since it isan insulator, as well as in the face seals of industrial respirators in automotive paintspray environments, where silicone must be avoided). EPDM is also used in glass-run channels, radiators, garden and appliance hose, tubing, pond liners, washers,belts, electrical insulation, vibrators, O-rings, solar panel heat collectors, and speakercone surrounds.

It is also used as a medium for water resistance in electrical cable-jointing, roofingmembranes (since it does not pollute the run-off rainwater, which is of vitalimportance for rainwater harvesting), geomembranes, rubber mechanical goods,

plastic impact modification, thermoplastic, vulcanizates, and many other applications.[6][7] Colored EPDM granulesare mixed with polyurethane binders and troweled or sprayed onto concrete, asphalt, screenings, interlocking brick,wood, etc. to create a non-slip, soft, porous safety surface for wet-deck areas such as pool decks and as safetysurfacing under playground play equipment (designed to help lessen fall injury).

The most common use, however, is probably in vehicles. It is used in door seals, window seals, trunk seals, andsometimes hood seals. Frequently, these seals are the source of noise due to movement of the door against the carbody and the resulting friction between the EPDM rubber and the mating surface (painted sheet metal or glass).This can be alleviated using specialty coatings that are applied at the time of manufacture of the weather seal. Suchcoatings can also greatly increase the chemical resistance of EPDM rubber. Some vehicle manufacturers alsorecommend a light application of silicone dielectric grease to weatherstripping to reduce noise. Other uses invehicles include cooling system circuit hoses where water pumps, thermostats, EGR valves, EGR coolers, heaters,oil coolers, radiators, and degas bottles are connected with EPDM hoses, as well as charge air tubing onturbocharged engines to connect the cold side of the charge air cooler (intercooler) to the intake manifold.

References

1. Ravishankar, P.S. (2012). "Treatise on EPDM" (http://dx.doi.org/10.5254/rct.12.87993). Rubber Chemistr and

Technolog 85. p. 327-349.

2. Green, Mark M.; Wittcoff, Harold A. (July 2003). Organic Chemistr Principles and Industrial Practice.

Weinheim, Germany: Wiley. p. 170. ISBN 978-3-527-30289-5. "In addition to natural rubber, many synthetic

rubberssuch asethylene-propylene-diene monomer rubber"

3. Louie, Douglas K. (2005). "Elastomers". Handbook of sulphuric acid manufacturing. Richmond Hill, Canada: DKL

Engineering, Inc. pp. 16116. ISBN 978-0-9738992-0-7. "EPDM (Ethylene Propylene Diene Monomer is a M class



Rubber containing a saturated chain of the polyethylene type."

4. "Designing with Rubber", Technical Documentation Orings (http://o-ring.info/en/technical%20manual/ERIKS%20-

%20Technical%20Manual%20-%20Designing%20with%20Rubber.pdf), Eriks, p. 33

5. http://www.allsealsinc.com/oilsseals.html

6. A om.com, Eth lene Prop lene Rubbers, Friday, 20 April 2012 (http://www.azom.com/article.aspx?

ArticleID=1822)

7. iisrp, Eth lene-Prop lene Rubbers & Elastomers, Friday, 20 April 2012

(http://www.iisrp.com/webpolymers/10epdmsep11.pdf)

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Categories: Elastomers

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