Neoprene and EPDM are both elastomers--long chain polymers that can be vulcanised. The vulcanisation process is responsible for the elastic properties of all the materials we commonly call rubber. Not all elastomers are the same, though. EPDM and Neoprene each have their own specific properties, and are the best choice in certain situations. Learning the properties of these elastomers can help you choose the right product for your needs.
Neoprene is the oldest of the two rubbers. It was invented in 1930 by scientists at DuPont, and has been used in all kinds of applications, such as electrical insulation, fan belts in vehicles, wet suits and laptop sleeves. The generic name for Neoprene is polychloroprene. EPDM, or ethylene propylene diene monomer, was developed in the 1960s, and is commonly used on flat roofs. EPDM is also used in seals and tubing, as electrical insulation, in pond liners and as a motor oil additive.
Neoprene and EPDM are similar in cost, resilience, tear strength and ability to resist damage from ozone. Both are easily damaged by petroleum-based fuels and are reasonably resistant to abrasion. They can withstand similar temperatures--a high of 149 degrees C for EPDM and 121 degrees Cor Neoprene, and a low of -60 and -40 respectively. EPDM has a significantly lower resistance to grease and oil than Neoprene and a significantly better resistance to water swell.
Each type of rubber is best for some uses. For instance, EPDM's resistance to ozone, UV rays, temperature extremes and water make it an excellent choice for waterproof roofing membrane. The material is available in liquid and sheet forms, and is usually applied using seamless techniques that reduce leakage. Neoprene has similar environmental resistances, withstands damage from twisting and flexing and resists burning relatively well. It can be made into an elastic foam that makes excellent insulation and cushioning material.
Some people are allergic to Neoprene, or contract contact dermatitis from one of the compounds used to vulcanise it. Some Neoprene adhesives also contain a substance called rosin, which is considered a skin sensitiser. Human allergies to EPDM are comparatively rare, and it is used in some non-latex rubber products, such as rubber bands.
Anyone interested in using an elastomer in manufacturing, construction or any other area should take the time to test the choices in actual application. While performance guides for each rubber can be useful in narrowing down the possibilities, there is no substitute for real world testing. A hasty decision could result in a poorly performing end product.