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Ethylene propylene rubber (EPM) is a synthetic rubber that is widely used as cable insulation, garden hoses, automobile seals and industrial belts. While ethylene propylene rubber is treated like a single product, there are two grades; one is entirely saturated, while the other has residual unsaturation. Along with being relatively easy to manufacture, there are many advantages to using ethylene propylene over natural rubber. It is resistant to heat, weathering, solvents, oxidation and ozone, making it versatile and useful for most industries. It also can be used to toughen up other polymer structures, but it is more often used by itself.
The term "ethylene propylene rubber" refers not to one polymer, but to two polymers whose main difference is the amount of chemical saturation in each. EPM is a co-polymer created from ethylene and propylene monomer structures. The entire structure is saturated, so radiation or compounds with free radicals must be used to create EPM. The separate EPDM is a ter-polymer from ethylene, propylene and diene. The main structure is saturated, but there are sections that are unsaturated that are commonly cured with sulfur; this makes it easier to chemically work with EPDM, because it will be more willing to interact with other substances.
The use of EPM can be found in many of the places where natural rubber is found. Among the most common usages, due to its advantages, are sealing strips in cars, cable insulation, mechanical goods based on rubber, and industrial belts and tubes. Places where ethylene propylene is found and rubber cannot be used include thermoplastic vulcanizates, plastic impact modifiers and as a motor oil additive.
Just like rubber, EPM is very stretchy and durable. There also are many other advantages afforded to ethylene propylene that makes it versatile and able to be used for many applications. It is resistant against both high temperatures and electricity and is not worn away by weathering from water, oxygen, acids or bases because of its heavily saturated nature. Ethylene propylene also is good against abrasives and has little oil swell.
It is entirely saturated, so ethylene propylene rubber is very tough and durable against most outside forces. These advantages are sometimes applied to other polymer compounds by mixing ethylene propylene with other polymers to toughen them up. While useful when coupled with other polymers, ethylene propylene is most often used as is, without being mixed.