EPDM rubber (ethylene propylene diene Monomer (M-class) rubber), a type of synthetic rubber, is an elastomer which is characterized by wide range of applications.The E refers to Ethylene, P to Propylene, D to diene and M refers to its classification in ASTM standard D-1418. The “M” class includes rubbers having a saturated chain of the polymethylene type. The diene(s) currently used in the manufacture of EPDM rubbers are DCPD (dicyclopentadiene), ENB (ethylidene norbornene) and VNB (vinyl norbornene).
The ethylene content is around 45% to 75%. The higher the ethylene content the higher the loading possibilities of the polymer, better mixing and extrusion. Peroxide curing these polymers give a higher crosslink density compared with their amorphous counterpart. The amorphous polymer are also excellent in processing. This is very much influenced by their molecular structure. The dienes, typically comprising between 2.5 wt% up to 12 wt% of the composition serve as crosslinks when curing with sulphur and resin, with peroxide cures the diene (or third monomer) functions as a coagent, which provide resistance to unwanted tackiness, creep or flow during end use.
EPDM rubber is used in vibrators and seals; glass-run channel; radiator, garden and appliance hose; tubing; washers; belts; electrical insulation, and speaker cone surrounds. It is also used as a medium for water resistance in electrical cable-jointing, roofing membranes, geomembranes, rubber mechanical goods, plastic impact modification, thermoplastic, vulcanizates, and many other applications.
EPDM exhibits satisfactory compatibility with fireproof hydraulic fluids, ketones, hot and cold water, and alkalis, and 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 polar substances and steam are also good. It has excellent electrical insulating properties. Typical properties of EPDM vulcanisates are given below. EPDM can be compounded to meet specific properties to 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)@125°C), varying levels of ethylene, third monomer and oil content.
|Hardness, Shore A||40 - 90|
|Tensile Failure Stress, Ultimate||25 MPa|
|Density||Can be compounded from 0.90 to >2.00 gcm-³|
|CTE, linear 68°F||875µm m-1 °C-1|
|Maximum Service Temperature, Air||100-120 °C|
|Minimum Service Temperature, Air||-54 °C|
|Glass Temperature||-54 °C|
Common applications in building
Solar Pool Panels
Extruded EPDM is used to make a solar heat collector for swimming pool solar water heating systems.
EPDM is used as a covering to waterproof roofs. It has the benefit that it does not pollute the runoff rainwater, which is of vital importance if the house owner wishes to use this water for personal sanitation/hygiene. Several houses equipped with rainwater harvesting thus make use of this type of roofing.
Playground/Pool Deck Surfacing
Granulated, colored EPDM granules are mixed with Polyurethane binders and trowled 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 or playgrounds.
- Green, Mark M.; Wittcoff, Harold A. (July 2003). Organic Chemistry Principles and Industrial Practice. Weinheim, Germany: Wiley. p. 170. ISBN 978-3-527-30289-5. "In addition to natural rubber, many synthetic rubbers...such as...ethylene-propylene-diene monomer rubber..."
- Louie, Douglas K. (2005). "Elastomers". Handbook of sulphuric acid manufacturing. Richmond Hill, Canada: DKL Engineering, Inc.. pp. 16–116. ISBN 9780973899207. "EPDM (Ethylene Propylene Diene Monomer is a M class Rubber containing a saturated chain of the polyethylene type."
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