EPDM rubber (ethylene propylene diene monomer rubber)[1][2][3] is a type ofsynthetic rubber that is used in many applications.
EPDM is an M-Class rubber underASTM standard D-1418; theM class compriseselastomers with asaturatedpolyethylene chain (the M deriving from the more correct term polymethylene). EPDM is made fromethylene,propylene, and adienecomonomer that enables crosslinking viasulfur vulcanization. Typically used dienes in the manufacture of EPDM rubbers areethylidene norbornene (ENB),dicyclopentadiene (DCPD), andvinyl norbornene (VNB). Varying diene contents are reported in commercial products, which are generally in the range from 2 to 12%.[4][5]
The earlier relative of EPDM is EPR,ethylene propylene rubber (useful for high-voltage electrical cables), which is not derived from any diene precursors and can be crosslinked only using radical methods such as peroxides.[6]
As with most rubbers, EPDM as used is always compounded withfillers such ascarbon black andcalcium carbonate, with plasticisers such as paraffinic oils, and has functional rubbery properties only whencrosslinked. Crosslinking mainly occurs viavulcanisation with sulfur but is also accomplished withperoxides (for better heat resistance) or phenolic resins. High-energy radiation, such as fromelectron beams, is sometimes used to produce foams, wire, and cable.
Typical properties of EPDM vulcanizates are given below. EPDM can be compounded to meet specific properties to a limit, depending first on the EPDM polymers available, then the processing and curing method(s) employed. EPDMs are available in various molecular weights (indicated in Mooney viscosity ML(1+4) at 125 °C), varying levels of ethylene, third monomer, and oil content.[citation needed]
Because of chemical interactions, EPDM degrades when in contact withbituminous material such as EPDM gaskets on asphalt shingles.[7]
| Property | Value |
|---|---|
| Appearance | Non-transparent black color |
| Hardness,Shore A | 30–90 |
| Tensile failure stress, ultimate | 17 MPa (500-2500 PSI) |
| Elongation after fracture in % | ≥ 300% |
| Density | Can be compounded from 0.90 to >2.0 g/cm3 |
| Property | Value |
|---|---|
| Coefficient of thermal expansion, linear[8] | 160 μm/(m·K) |
| Maximum service temperature[9] | 150 °C |
| Minimum service temperature[9] | −50 °C |
| Glass transition temperature | −54 °C |
Relative to rubbers with unsaturated backbones (natural rubber,SBR,neoprene), rubbers with saturated polymer backbones, such as EPDM, exhibit superior resistance to heat, light, and ozone exposure. For this reason they are useful in external harsh environments.[10] EPDM in particular exhibits outstanding resistance toheat,ozone,steam, andweather. As such, EPDM can be formulated to be resistant to temperatures as high as 150 °C, and, properly formulated, can be used outdoors for many years or decades without degradation. EPDM has good low-temperature properties, with elastic properties to temperatures as low as −40 °C depending on the grade and the formulation.
EPDM is stable towards fireproofhydraulic fluids, ketones, hot and cold water, and alkalis.
As a durableelastomer, EPDM is conformable, impermeable, and a good electrical insulator. Solid EPDM and expanded EPDM foam are often used forsealing andgasketing, as well asmembranes anddiaphragms. EPDM is often used when a component must preventfluid flow while remaining flexible. It can also be used to providecushioning orelasticity. While EPDM has decenttensile strength, its flexibility makes it inappropriate for rigid parts such asgears,shafts, and structural beams.
It is used to create weatherstripping, seals on doors forrefrigerators andfreezers (where it also acts as aninsulator), face masks for industrial respirators,glass run channels,radiators, garden and appliancehose (where it is used as a hose material as well as for gaskets),tubing,washers,O-rings,electrical insulation, andgeomembranes.
A common use is invehicles, where EPDM is used for door seals, window seals, trunk seals, and sometimes hood seals.[11] Other uses in vehicles includewiper blades,[12] cooling system circuit hoses; water pumps, thermostats, EGR valves, EGR coolers, heaters, oil coolers, radiators, and degas bottles are connected with EPDM hoses. EPDM is also used as charge air tubing onturbocharged engines to connect the cold side of the charge air cooler (intercooler) to theintake manifold.
EPDM seals can be a source of squeaking noise due to the movement of the seal against the opposing surface (and its attendant friction). The noise can be alleviated using specialty coatings that are applied at the time of manufacture of the seal. Such coatings can also improve the chemical resistance of EPDM rubber. Some vehicle manufacturers also recommend a light application ofsilicone dielectric grease to weatherstrip to reduce noise[citation needed].
This synthetic rubber membrane has also been used for pond liners andflat roofs because of its durability and low maintenance costs.[13] As aroofing membrane it does not pollute the run-off rainwater (which is of vital importance forrainwater harvesting).[14]
It is used forbelts,electrical insulation,vibrators,solar panel heat collectors, and speaker cone surrounds. It is also used as a functional additive to modify and enhance the impact characteristics ofthermoset plastics,thermoplastics, and many other materials.[15][16]
EPDM is also used for components that provideelasticity; for example, it is used forbungee cords, elastic tie-downs, straps, and hangers that attach exhaust systems to the underfloor of vehicles (since a rigid connection would transfer vibration, noise, and heat to the body). It is also used for cushioned edge guards and bumpers on appliances, equipment, and machinery.
Colored EPDM granules are mixed with polyurethane binders and troweled or sprayed onto concrete, asphalt, screenings, interlocking brick, wood, etc., to create a non-slip, soft, porous safety surface for wet-deck areas such as pool decks.[17] It is used as safety surfacing under playground play equipment (designed to help lessen fall injury).[17] (seePlayground surfacing.)
Production of synthetic rubber in the 2010s exceeded 10 million tonnes annually and was over 15 million tonnes in each of 2017, 2018, and 2019 and only slightly less in 2020.[18]
In addition to natural rubber, many synthetic rubbers... such as... ethylene-propylene-diene monomer rubber...
EPDM (Ethylene Propylene Diene Monomer) is a M class Rubber containing a saturated chain of the polyethylene type.
