Natural / Isoprene:
Natural rubber is a polymer of isoprene and has a molecular weight of 100,000 to 1,000,000. An organic material, sometimes traces of other materials such as proteins, resins and inorganic materials can be found in high quality natural rubber. Natural rubber is formed in the bark of tropical trees. Isoprene’s chemical and structural makeup is very similar to natural rubber’s. Both can be used for similar applications although isoprene rubber has less green strength than natural rubber.
Ethylene Propylene Diene (EPDM)
A synthetic rubber and elastomer characterized by a wide range of applications. EPDM (which stands for Ethylene Propylene Diene Monomers) is an extremely high-density synthetic rubber material that is versatile and capable of serving several roles for outdoor applications. EPDM’s density boasts strong resistance to weather aging, ozone, sunlight, water, heat, phosphate, electricity as well as tensile strength. These properties make EPDM a slightly less expensive alternative to Silicone.
EPDM is also useful for use with automotive. However, it has a tendency to swell when in the presence of petroleum, oils and similar solvents and should, therefore, be used with caution when used for these purposes.
Nitrile Rubber (NBR)
Nitrile (also known as Buna-N) is a copolymer of butadiene and acrylonitrile and one of the strongest rubber materials in applications involving oil and fuel. Add on top of that NBR is extremely resistant to oil and is therefore used in automotive seals, gaskets and other products that contact hot oils and fuels. The more nitrile in the product’s composition, the more resistant to oil it becomes at the expense of flexibility. NItrile rubber is also a very resilient material making it ideal for products such as cleaning and examination gloves. Gloves made with nitrile rubber are three times more resistant to punctures than gloves made with natural rubber or isoprene.
Despite is strength against fuel and oil, it is important to note that Nitrile’s largest downfall is its weakness against oxygen, ozone and sunlight. While Nitrile also has decent cold resistance, it is inferior to natural rubbers which may cause you to look elsewhere.
Styrene Butadiene Rubber (SBR)
Styrene butadiene rubber is a synthetic rubber that is more resistant to abrasion than natural rubber. It is predominantly used in automobile and truck tires as it stands up to heat and cracks and ages well. The higher the styrene content in the rubber, the harder and less flexible the product becomes.
Silicone Rubber
When it comes to extreme conditions, Silicone is the top pick. Silicone rubber is a polymer composed of silicon combined with carbon, hydrogen and oxygen. Materials made with this synthetic rubber are extremely resistant to heat and cold, being able to withstand temperatures ranging from -150ºF(-150C) to +480ºF(+250C). Additionally, Silicone has solid resistances to electricity and water, as well as a long service life. Resilient and durable, silicone rubber materials resist prolonged exposure to sunlight, oxygen, ozone, moisture and UV light.
Silicone rubber does have its weaknesses however as products made of the elastomer are subject to tears and abrasions. During manufacturing, heat is required to vulcanize (cure) the silicone into its rubber-like form, it’s tensile resistance is still relatively low. Silicone is recommended primarily for applications in extreme conditions.
Butyl Rubber
Butyl is a synthetic rubber, also referred to as isobutylene isoprene. Butyl rubber has a variety of uses and applications but its true value is its impermeability to air and gases. Butyl is also very resistant to water and steam, which is why butyl rubber is used in sealants for damp proofing, rubber roof repair and rubber membrane maintenance. First used as tire inner tubes, butyl rubber is now applied to sporting ball bladders, gas masks and protective clothing, vial stoppers, explosives, chewing gum and is even used as an additive in lubricating oils and motor fuels. The addition of small amounts of polyisobutylene in lubricating oils results in a significant reduction of oil mist inhaled by a machine operator.
Neoprene
Neoprene was the first mass-produced synthetic rubber and is considered to be one of the best general-purpose choices in rubber materials because of its versatility for both indoor and outdoor applications. Temperature range and tensile strength make it useful for automotive, refrigeration and HVAC applications.
While Neoprene does many things well, there are other kinds of rubber material that may be more specialized and therefore appropriate for certain applications.
Viton
Introduced over 60 years ago to the aerospace industry, Viton is a high-performance rubber material that is ideal for high-temperature applications. Viton can withstand temperatures upwards of +260C (+500F), similar to Silicone. Since it’s introduction, Viton has spread to use in the automotive, chemical and fluid power industries as a reliable product for seals, hoses and gaskets because of its heat and corrosive resistance.
The strength of Viton is undeniable, but it does come with a higher price tag than other high-temperature resistant rubber materials. However, in applications with extreme heat, Viton is often worthy of the price tag.