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EPDM meaning in Space Science ?

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Answer: What is Ethylene Propylene Diene Monomer mean?

EPDM rubber (ethylene propylene diene monomer rubber) is a type of synthetic rubber that is used in many applications.

EPDM is an M-Class rubber under ASTM standard D-1418; the M class comprises elastomers having a saturated chain of the polyethylene type (the M deriving from the more correct term polymethylene). EPDM is made from ethylene, propylene, and a diene comonomer that enables crosslinking via sulfur vulcanization. The earlier relative of EPDM is EPR, ethylene propylene rubber, that contains no diene units and can only be crosslinked using radical methods such as peroxides. Dienes used in the manufacture of EPDM rubbers are ethylidene norbornene (ENB), dicyclopentadiene (DCPD), and vinyl norbornene (VNB).

EPDM is derived from polyethylene into which 45-85 wt% of propylene have been copolymerised to reduce the formation of the typical polyethylene crystallinity. EPDM is a semi-crystalline material with ethylene-type crystal structures at higher ethylene contents, becoming essentially amorphous at ethylene contents that approach 50 wt%.

Rubbers with saturated polymer backbones, such as EPDM, have much better resistance to heat, light and ozone than unsaturated rubbers such as natural rubber, SBR, or neoprene (polychloroprene). This makes it suitable to be utilised in external harsh environments. As such, EPDM can be formulated to be resistant to temperatures as high as 150 °C, and, properly formulated, can be used outdoors for many years or decades without degradation. EPDM has good low temperature properties, with elastic properties to temperatures as low as -40 °C depending on the grade and the formulation.

As with most rubbers, EPDM is always used compounded with fillers such as carbon black and calcium carbonate, with plasticisers such as paraffinic oils, and has useful rubbery properties only when crosslinked. Crosslinking mostly takes place via vulcanisation with sulfur, but is also accomplished with peroxides (for better heat resistance) or with phenolic resins. High-energy radiation such as from electron beams is sometimes used for producing foams and wire and cable.

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