The EPDM elastomer is one of the more interesting types of rubber. Chemically known as ethylene propylene diene monomer rubber, it possesses many traits that are characteristic of conventional elastomers, such as tear resistance, a high tensile strength, and a low compression set. Of course, this doesn’t set EPDM products apart from other elastomers like SBR or NBR that also have similar physical properties. The unique property of EPDM is found in its ability to resist degradation resulting from weathering agents like UV rays and ozone. In addition to this, it is also very resistant to polar substances and steam. What is EPDM material and how is it used? The above properties, combined with the other conventional traits, make for the perfect weather resistant rubber.

Industry professionals in roofing, automotive, and other applications use EPDM sheet rubber to produce components that can perform and last through outdoor conditions. It is the tried-and-true elastomer for weathering. However, it begs the question: what makes the EPDM elastomer so resistant to weathering from UV rays and ozone? The answer lies within the rubber’s chemical composition.

While rubber had been in use for centuries, it was only in the 20th century that the push for synthetic rubbers began. These man-made elastomers were engineered to possess certain traits, such as NBR’s resistance to oil and grease. In the 1960’s, several chemical companies, like DuPont, Exxon, and Uniroyal, were trying to engineer a weather resistant rubber. The hard work paid off and the result was ethylene propylene diene monomer rubber, commonly known as EPDM. It was not long before it was picked up for use in roofing applications. It was DuPont, in particular, who further refined the material and eventually it had largely replaced asphalt as the roofing material of choice (http://epdmrubberroofing.blogspot.com/2009/09/history-of-epdm.html).

Before going into the defining trait of EPDM elastomer, it is important to first grasp how exactly it is that UV rays and ozone can damage a material, let alone an elastomer. UV, or ultra-violet radiation, is a light that is invisible to the human eye. It is emitted from the sun as well as other sources like black lights. Ozone is a molecule naturally found as a gas in the Earth’s atmosphere. Upon contact with a material, both UV and ozone attack any vulnerable chemical bonds (i.e., double bonds) in the material’s chemical backbone. This alters the molecular structure of said material. When the material’s chemical backbone is modified or tampered with in any way, degradation will occur.

What is EPDM material and why is it chosen over other polymers? Elastomers like natural rubber, NBR and SBR all have double bonds in their chemical backbone commonly referred to as “unsaturated”. Such rubbers react adversely to weathering and result in discoloration, hardening, and ozone cracking. Ethylene propylene diene monomer rubber has a saturated chemical backbone that contains single bonds that are not vulnerable to UV and ozone. EPDM elastomer does have a few unsaturated groups in its molecular structure, which means it is not completely UV- and ozone-resistant, but the saturated backbone is sufficient enough to give the rubber such a high degree of weather resistance that it might as well be considered close to immune. Only a few general-purpose elastomers have a saturated backbone, silicone being another good example of this.

It should come as no surprise that these chemical properties make EPDM products a favorite choice of elastomer in many industries. As mentioned above, this weather resistant rubber made a name for itself in the commercial roofing industry. Eventually, the automobile industry caught on to its existence. EPDM sheet rubber is used in radiators, cold-room doors, roofing membranes, hoses, electrical insulators, and other outdoor appliances. However, the area that EPDM elastomer is most commonly used is in automobiles. It is used in window seals, door seals, trunk seals, and hood seals. Most, if not all, of the hose tubing that is present in the engine area of a vehicle is made of EPDM.

The molecular-level traits of EPDM products may be irrelevant to most people that are simply looking for a flexible material that will work well as a weather resistant rubber. That is perfectly fine since every piece of EPDM sheet rubber will have the same degree of functionality. At the end of the day, function is the most important factor. However, the chemists who invented the EPDM elastomer rightly deserve credit. Many industries would not be what they are today without this material. Our own lives would be more difficult. Without EPDM in our vehicles, our maintenance bills would likely be a lot higher. To find our what is EPDM material, see our line of EPDM products. If you have any questions, feel free to give one of our specialists a call so that they can help you with your needs.