Ethylene propylene rubber (EPR, sometimes called EPM referring to an ASTM standard) is a type of synthetic elastomer that is closely related to EPDM rubber. Since introduction in the 1960s, annual production has increased to 870,000 metric tons. http://www.azom.com/article.aspx?ArticleID=1822 ''Azom.com'', ''Ethylene Propylene Rubbers'', Thursday 19 April 2012http://www.iisrp.com/webpolymers/10epdmsep11.pdf ''iisrp'', ''Ethylene-Propylene Rubbers & Elastomers'', Thursday 19 April 2012

EPR is used in electrical cable insulation, and in many flexible rubber goods such as hoses or weatherstripping.

Properties

EPM is considered a valuable elastomer due to its useful

chemical A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combin ...

and physical properties; it is resistant to

heat In thermodynamics, heat is energy in transfer between a thermodynamic system and its surroundings by such mechanisms as thermal conduction, electromagnetic radiation, and friction, which are microscopic in nature, involving sub-atomic, ato ...

oxidation Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

ozone Ozone () (or trioxygen) is an Inorganic compound, inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , break ...

and the

weather Weather is the state of the atmosphere, describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or cloud cover, cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmo ...

(owing to its stable, saturated backbone) and it is also not susceptible to color loss. As a non-polar compound, EPM is an

electrical insulator An electrical insulator is a material in which electric current does not flow freely. The atoms of the insulator have tightly bound electrons which cannot readily move. Other materials—semiconductors and electrical conductor, conductors—con ...

and it is insoluble in many polar

solvents A solvent (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for p ...

, both protic and aprotic.

Amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid) is a solid that lacks the long-range order that is a characteristic of a crystal. The terms "glass" and "glassy solid" are sometimes used synonymousl ...

forms of EPM are flexible at low temperatures (with glass transition points around -60 °C). Via selection of certain

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

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.

Polymer properties

Uses

EPM has a large number of uses due to the many ways in which the

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

can be designed, for example; it is used in automotive weather-stripping and seals, self-amalgamating tape, glass run channels, radiators, garden and appliance hoses, tubing, belts, roofing membranes, expansion joints, rubber mechanical goods, plastic impact modification, thermoplastic vulcanisates and

motor oil Motor oil, engine oil, or engine lubricant is any one of various substances used for the lubrication of internal combustion engines. They typically consist of base oils enhanced with various additives, particularly antiwear additives, deterge ...

additive applications. EPM is even more prevalent as an insulator for high-voltage cables (usually referred as HEPR - Hard grade Ethylene Propylene Rubber) since it has improved insulative characteristics over more traditional cables, such as cross-linked polyethylene, enabling a smaller cross sectional area for the same load carrying capacity. The cable is flexible and suited to applications where regular cable movement is required such as in the mining industry.

Producers

Major producers and suppliers of EPM include Crompton Corporation, Exxon-Mobil,

Dupont Dupont, DuPont, Du Pont, duPont, or du Pont may refer to: People * Dupont (surname) Dupont, also spelled as DuPont, duPont, Du Pont, or du Pont is a French surname meaning "of the bridge", historically indicating that the holder of the surname re ...

, Herdillia, Kumho Polychem, LANXESS, Mitsui Chemicals, ENI Versalis and Sumitomo Chemical.

Manufacture

EPM manufacture uses the same monomers as polyethene and polypropene, the ethylene and propylene monomers are randomly combined to yield a rubbery, stable polymer. By varying the monomer ratios and method by which the monomers are combined different forms of EPM can be formed (with a wide range of Mooney viscosities); ranging from amorphous to semi-crystalline. A third, non-conjugated

diene In organic chemistry, a diene ( ); also diolefin, ) or alkadiene) is a covalent compound that contains two double bonds, usually among carbon atoms. They thus contain two alk''ene'' units, with the standard prefix ''di'' of systematic nome ...

monomer can be terpolymerized in a controlled manner to maintain an unsaturated backbone ready for vulcanization or polymer modification.

References