Ethylene propylene rubber (EPR, sometimes called EPM referring to an ASTM standard) is a type of synthetic

elastomer An elastomer is a polymer with viscoelasticity (i.e. both viscosity and elasticity) and with weak intermolecular forces, generally low Young's modulus and high failure strain compared with other materials. The term, a portmanteau of ''elastic p ...

that is closely related to EPDM rubber. Since introduction in the 1960s, annual production has increased to 870,000

metric tons The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United States ...

. 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 form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wi ...

and

physical properties A physical property is any property that is measurable, whose value describes a state of a physical system. The changes in the physical properties of a system can be used to describe its changes between momentary states. Physical properties are o ...

; it is resistant to

heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is al ...

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

ozone Ozone (), or trioxygen, is an 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 , breaking down in the lo ...

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 cloudy. On Earth, most weather phenomena occur in the lowest layer of the planet's atmosphere, the ...

(owing to its stable, saturated

backbone The backbone is the vertebral column of a vertebrate. Arts, entertainment, and media Film * ''Backbone'' (1923 film), a 1923 lost silent film starring Alfred Lunt * ''Backbone'' (1975 film), a 1975 Yugoslavian drama directed by Vlatko Gilić M ...

) and it is also not susceptible to color loss. As a

non-polar In chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole moment, with a negatively charged end and a positively charged end. Polar molecules must contain one or more pola ...

compound, EPM is an

electrical resistor A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active el ...

and it is

insoluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubil ...

in many

polar Polar may refer to: Geography Polar may refer to: * Geographical pole, either of two fixed points on the surface of a rotating body or planet, at 90 degrees from the equator, based on the axis around which a body rotates * Polar climate, the c ...

solvents A solvent (s) (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 In chemistry, a protic solvent is a solvent that has a hydrogen atom bound to an oxygen (as in a hydroxyl group ), a nitrogen (as in an amine group or ), or fluoride (as in hydrogen fluoride). In general terms, any solvent that contains a labile ...

and

aprotic A polar aprotic solvent is a solvent that lacks an acidic proton and is polar. Such solvents lack hydroxyl and amine groups. In contrast to protic solvents, these solvents do not serve as proton donors in hydrogen bonding In chemistry, a hydro ...

Amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal. Etymology The term comes from the Greek ''a'' ("wi ...

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

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

compounds EPM can remain heat resistant up to 130 °C and up to 160 °C with

peroxide In chemistry, peroxides are a group of compounds with the structure , where R = any element. The group in a peroxide is called the peroxide group or peroxo group. The nomenclature is somewhat variable. The most common peroxide is hydrogen p ...

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 (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

can be designed, for example; it is used in automotive weather-stripping and

seals Seals may refer to: * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, or "true seal" ** Fur seal * Seal (emblem), a device to impress an emblem, used as a means of a ...

self-amalgamating tape Self-amalgamating tape is a non-tacky silicone-rubber tape which when stretched and wrapped around cables, electrical joints, hoses and pipes combines or unites itself into a strong, seamless, rubbery, waterproof, and electrically insulating laye ...

glass run channel A glass run channel is a groove, normally made of rubber or plastic, that is found around windows (most commonly car windows). The primary purpose of a glass run channel is to provide a seal Seal may refer to any of the following: Common u ...

radiator Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in cars, buildings, and electronics. A radiator is always a ...

s, garden and appliance hoses, tubing, belts, roofing membranes,

expansion joints An expansion joint, or movement joint, is an assembly designed to hold parts together while safely absorbing temperature-induced expansion and contraction of building materials, and vibration, or to allow movement due to ground settlement or seis ...

, 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, deterg ...

additive applications. EPM is even more prevalent as an insulator for

high-voltage cable A high-voltage cable (HV cable) is a cable used for electric power transmission at high voltage. A cable includes a conductor and insulation. Cables are considered to be fully insulated. This means that they have a fully rated insulation system t ...

s (usually referred as HEPR - Hard grade Ethylene Propylene Rubber) since it has improved insulative characteristics over more traditional cables, such as

cross-linked polyethylene Cross-linked polyethylene, commonly abbreviated PEX, XPE or XLPE, is a form of polyethylene with cross-links. It is used predominantly in building services pipework systems, hydronic radiant heating and cooling systems, domestic water piping, ins ...

, enabling a smaller

cross sectional area In geometry and science, a cross section is the non-empty intersection of a solid body in three-dimensional space with a plane, or the analog in higher- dimensional spaces. Cutting an object into slices creates many parallel cross-sections. T ...

for the same

load Load or LOAD may refer to: Aeronautics and transportation *Load factor (aeronautics), the ratio of the lift of an aircraft to its weight *Passenger load factor, the ratio of revenue passenger miles to available seat miles of a particular transpo ...

carrying capacity. The cable is flexible and suited to applications where regular cable movement is required such as in the

mining industry Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic via ...

Producers

Major producers and suppliers of EPM include

Crompton Corporation Crompton Corporation (, formerly Crompton and Knowles) was a chemical research, production, sales and distribution company headquartered in Middlebury, Connecticut. The company produced specialty chemicals used for polymers, fire suppressants and ...

Exxon-Mobil ExxonMobil Corporation (commonly shortened to Exxon) is an American multinational oil and gas corporation headquartered in Irving, Texas. It is the largest direct descendant of John D. Rockefeller's Standard Oil, and was formed on November 3 ...

Dupont DuPont de Nemours, Inc., commonly shortened to DuPont, is an American multinational chemical company first formed in 1802 by French-American chemist and industrialist Éleuthère Irénée du Pont de Nemours. The company played a major role in ...

, Herdillia,

Kumho Polychem Kumho Polychem is a part of South Korean conglomerate Kumho Petrochemical, Kumho Petrochemical Group, operating a factory located in Yeosu Industrial Complex. It manufactures EPDM rubbers, Santoprene, TPVs and KEPA. It was founded in 1985 and is ...

LANXESS Lanxess AG is a German specialty chemicals company based in Cologne, Germany that was founded in 2004 via the spin-off of the chemicals division and parts of the polymers business from Bayer AG. Shares in Lanxess AG were listed in Germany’s DA ...

Mitsui Chemicals is a Japanese chemicals company listed on the Nikkei with business interests in Japan, Europe, China, Southeast Asia and the USA. It is one of the leading chemical companies in Japan and is part of the Mitsui conglomerate. The company mainly ...

, ENI Versalis and

Sumitomo Chemical is a major Japanese chemical company. The company is listed on the first section of the Tokyo Stock Exchange and is a constituent of the on the Nikkei 225 stock index. It's a member of the Sumitomo group and was founded in 1913 as a fertilize ...

Manufacture

EPM manufacture uses the same

monomers In chemistry, a monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization. Classification M ...

polyethene Polyethylene or polythene (abbreviated PE; IUPAC name polyethene or poly(methylene)) is the most commonly produced plastic. It is a polymer, primarily used for packaging (plastic bags, plastic films, geomembranes and containers including bott ...

and polypropene, the

ethylene Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). Ethylene i ...

and

propylene Propylene, also known as propene, is an unsaturated organic compound with the chemical formula CH3CH=CH2. It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petrole ...

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 ( ) (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 nomenclature. ...

monomer can be terpolymerized in a controlled manner to maintain a saturated backbone ready for

vulcanization Vulcanization (British: Vulcanisation) is a range of processes for hardening rubbers. The term originally referred exclusively to the treatment of natural rubber with sulfur, which remains the most common practice. It has also grown to include ...

or polymer modification.

References