Ethylene propylene rubber


Ethylene propylene rubber 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.
of ethylene propylene rubber. |The skeletal formula of ethylene propylene rubber. 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 and physical properties; it is resistant to heat, oxidation, ozone and the weather 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. 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.

Polymer properties

Property typeEPM Property
Hardness 30–95
Tensile strength 7–21
Elongation100–600%
Compression set B20–60%
Useful temperature range −50 to +160
Tear resistanceFair to good
Abrasion resistanceFair to good
ResilienceFair to good
Electrical propertiesInsulator

Uses

EPM has a large number of uses due to the many ways in which the polymer 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 additive applications.
EPM is even more prevalent as an insulator for high-voltage cables 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, 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 ; ranging from amorphous to semi-crystalline. A third, non-conjugated diene monomer can be terpolymerized in a controlled manner to maintain a saturated backbone ready for vulcanization or polymer modification.