EPDM is a synthetic rubber used in various industries due to its versatility and employability in a number of sectors – one of which is the automotive industry – where rubber is needed with special qualities. But what are these special qualities that made possible the widespread use of EPDM in so many areas? And why was there a growing need for it?
Natural rubber had qualities that deteriorated over time due to exposure to UV light, ozone, weather conditions or constantly changing temperatures. In order to cover the needs of the ever growing industries using rubber as a key material in production, in the early 1960s companies set out to produce unique synthetic rubber materials where resistance to UV exposure over long periods of time was essential. EPDM is a result of this era, a type of synthetic rubber that is used in many applications.
What is EPDM?
EPDM stands for ethylene propylene diene monomer, which is a bit of a mouthful, so it’s commonly shortened to EPDM or EPDM rubber. EPDM gets its name from the chemicals (monomers) that are mixed together in various proportions: ethylene, propylene and diene, where the ethylene content is usually between 45% to 75%.
The diene monomers, while they only make up a small part of the composition of EPDM, provide the cross-linking that gives incredible resilience, flexibility and durability. The excellent material properties of EPDM come from this molecular mesh structure and make it unbeatable in terms of elasticity and resistance to ageing. It can be applied to various products owing to its low hardness and high slip resistance properties.
Compounds with saturated polymer backbones have much better heat resistant properties than unsaturated rubbers such as natural rubber.
Physical properties of EPDM
Its excellent physical properties make EPDM widely popular for a variety of applications. Let’s see what properties make it such a versatile raw material for many industries:
outstanding weather resistance,
thermal and oxidative stability,
chemical resistance to polar organic and aqueous inorganic fluids, compatible with fireproof hydraulic fluids, ketones and alkalis,
good low temperature (-40 °C) sealing property,
collapse resistance and dimensional stability.
Hardness, Shore A
Tensile failure stress, ultimate
17 MPa (500-2500 PSI)
Can be compounded from 0,90 to > 2,00 g cm3
If properly taken care of, EPDM products can last for decades. Roofing made from EPDM can last 30-50 years, and liners can last for 20 years.
What are the benefits of EPDM?
Today EPDM manufacturing is one of the fastest growing segment of the synthetic rubber market, being the primary choice for automotive and industrial applications. It has long replaced natural rubber. EPDM is used in automotive and industrial hose products due to their thermal and oxidative stability and chemical resistance to polar organic and aqueous inorganic fluids.
EPDM has great noise reduction properties and it also bonds quickly with metal which gives a strong barrier against weather conditions as well as the environment, road surface and engine vibration. What’s more it has low electrical conductivity and is also steam and water resistant.
Excellent physical properties of EPDM make EPDM hoses extremely durable. They may have a longer lifespan than the car itself that they are built in.
Where else is EPDM used today?
EPDM is used in the automotive and construction industry for sealing purposes, as window and door seals, protective pads and electrical gaskets, as well. You may come across EPDM in heating, ventilation and air conditioning machinery, such as compressor grommets, mandrel-formed drain tubes, pressure switch tubing.
Manufacturing best practices to increase performance of EPDMs
Performance of EPDMs can be altered by using different manufacturing processes and adding various ingredients. Compounds are designed depending on the physical properties we’re looking for.
Compounded materials can achieve a broad range of tensile strength and durametric requirement, and for such purposes, it is frequently compoundedwith fillers such as carbon black and calcium carbonate.
When compounded with paraffinic oils, it shows higher elastic properties.
EPDM elastomers cured with sulphur, showing better compression set and improved physical properties, are ideal for low to medium service temperatures. Cross-linking is achieved via vulcanization with sulphur or peroxides that ensure strengthening coating properties. Curing with peroxide allows for higher service temperatures.
Where does the automotive industry need special EPDM solutions?
Given that the automotive industry is one of the fastest evolving industries, innovation is on demand for its products to stay ahead in the game. This is why we have seen such rapid developments in automobile design, bringing about the need to further develop parts and components to meet higher requirements.
Heat resistance is key
With the lowering of hood lines, hood temperatures became higher and have brought along the need for greater heat-resistant compounds. The temperature around areas like brakes and battery can increase very quickly and It falls just as quickly when the car is stopped. Any part used here has to have the ability to work in such conditions without expanding, cracking or breaking up.
Today’s engines consume less fuel and have lower emissions than ever before without compromising on performance. Such trends had an indirect effect on hose development, Since hoses needed to adapt to engines that run hotter.
EPDM can withstand extremely high temperature fluctuations. Even a general purpose EPDM can withstand temperatures in the range of -29 ⁰C to 110 ⁰C (this can be increased to up to 130⁰C with certain additions), thus it can be used for items such as coolants, emissions, brake hoses and air ducts.
Sealing and bumpers
As the car runs full throttle, the sealing of parts like doors, windows and engine is also critical. EPDM’s flexibility provides protection against vibration and it has noise reducing properties, as well.
EPDM can also be found in vehicle weather stripping, seals, sealant, wire and cable harnesses, and brake systems. Blends of EPDMs and other polymers (PP) are also used for car bumpers, fender extensions, and rub strips.
End-use performance requirements of the automotive industry
Despite the commercialization of compounds with improved quality and consistency, radiator and heater hoses in certain vehicle models and designs develop cracks well before their expected service life capability. In order to provide proper quality
automotive coolants, air and heater hoses and the AC system and brake hoses must have high green and tear strength, age well, have a low temperature flexibility and compression set should also be easy to mix with other materials.
EPDM hoses meet all of these requirements, therefore, they are widely used from general purpose hoses to high-heat resistant hoses. However, very high-heat resistant hoses are rather made of silicone rubbers. The performance standard for coolant hoses is specified in SAE J20, SAE 20R3 for heater hoses and SAE R4 for radiator hoses. based on these requirements, we recognize three classes of hose materials:
70 hr at 125 °C
sulfur cured EPDM elastomers
70 hr at 150 °C
blend of amorphous and crystalline EPDM
70 hr at 175 °C
SIC products made of EPDM for automotive applications
We manufacture a wide range of products made of EPDM for automotive applications such as air intake hoses, air cleaners and automotive filters, grommets, bellows, wiring harness, profiles.
We offer reinforced and non-reinforced hoses. We recommend re-enforced EPDM hoses for high-pressure or vacuum environments. Coolant hoses are known for organic-acid based coolant resistance.
When it comes to being used for air intake, EPDM may be a more cost-effective option than silicon.
We manufacture gaskets in all sizes and shapes according to custom specifications.
Rubber cones are also made of EPDM as a unique solution with rubber remaining flexible also at -40 C°.
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