Ethylene propylene rubber

Ethylene propylene rubber (EPR, sometimes called EPM, the E refers to ethylene, P to propylene and M refers to its classification in ASTM standard D-1418 since the M class includes rubbers having a saturated chain of the polymethylene type) is a type of synthetic elastomer that is closely related to EPDM rubber (EPM is a copolymer of ethylene and propylene whereas EPDM rubber is a terpolymer of ethylene, propylene and a diene-component). Since it began to be produced in the 1960s, production has increased to 870,000 metric tons per annum, mostly due to advances in polymerization and catalyst technologies which allow polymers to be designed for specific purposes.

EPM is considered a valuable elastomer due to its useful chemical and physical properties; it is resistant to heat, oxidation, ozone and the weather (owing to its stable, saturated backbone) and it is also not susceptible to color loss. As a non-polar compound, EPM is an electrical resistor and it is insoluble in many polar solvents, both protic and aprotic. Amorphous forms of EPM are flexible at low temperatures (with glass transition points around -60 °C). Via selection of certain sulfur compounds EPM can remain heat resistant up to 130 °C and up to 160 °C with peroxide curing. These two tables contain some of the main properties of EPM.