Which Rubber/Elastomer Offers the Best Water Resistance?
Rubber & Elastomer
What are rubber and elastomers? An elastomer is a natural or synthetic polymer with elastic properties. Elastomers are flexible and able to withstand stretching and pressure, making them excellent for a wide variety of applications.
Rubber, both synthetic and natural, is a type of elastomer.
Apart from their ability to be manipulated and stretched without breaking, elastomers and rubber are often used in wet applications. Waterproof rubber completely rejects liquid, while water resistant rubber provides strong protection against liquid, but is not entirely impervious.
Waterproof rubber and elastomers are found in:
- Exterior or wet-location paint
- Clothing, including winter boots and performance gear
If end-use performance requires waterproof rubber or water resistant rubber, a number of types of rubber and elastomers are available.
Types of Rubber/Elastomers
There are many types of rubber and elastomers. The following are some of the most common types, each with their own characteristics and best applications.
EPDM is a combination of ethylene, propylene, and a diene monomer. It is extremely resistant to weather aging, ozone, UV exposure, water, heat, and electrical insulation. EPDM is not used with petroleum oils, fluids, or solvents due to swelling.
EPDM is a widely used synthetic rubber, used often wherever weather and water resistance properties are required.
The first major application of butyl rubber was inner tire tubes. It is highly resistant to gas and moisture, as well as flexing and abrasion. One limitation of butyl rubber is the possibility of trapped air blistering the product in the manufacturing process.
Butyl is commonly used for vacuum seals, inner tire liners, and hydraulics applications with synthetic fluid
Natural rubber comes from latex extracted from rubber trees. It has excellent tensile strength, elongation properties, and resistance to water and cold flow. However, natural rubber does deteriorate when exposed to oil, field, solvents, and hydraulic fluids. Special additives are advised when natural rubber will be exposed to sunlight, oxygen, ozon, and high temperatures.
Natural rubber is widely used in tires, gaskets, electrical components, bumpers, and many more applications.
Chloroprene is a versatile synthetic rubber with good resistance to moderate exposure to a number of environmental factors, including sunlight, weather, oils, greases, and petroleum oils. It is also excellent for adhesion to metals and fabrics. Its greatest disadvantage is its cost, which can be higher than lower-priced materials that perform similarly.
Neoprene is most often used in applications in which a seal is exposed to weathering refrigerants, silicate ester lubricants, and high aniline point petroleum oils.
Nitrile, also known as Buna-N, is a general purpose polymer with excellent resistance to oils, gasoline, solvents, hydraulic fluid, and fuels. It can also withstand a wide range of temperatures. Its ozone, oxygen, and sunlight resistance are weaker, so additives must be used to improve these areas of performance.
Nitrile is a good choice for any application where a polymer that is extremely resistant to oils, gasoline, and greases is necessary. For this reason, nitrile is the most commonly used elastomer for sealing products.
Polyisoprene closely resembles natural rubber. Its greatest strength is its color uniformity, which makes it easy to maintain one color over multiple batches of the synthetic elastomer. Its tensile strength is slightly low in comparison to natural rubber.
Polyisoprene is used in applications where color uniformity and quality are important, including many consumer goods.
SBR (styrene butadiene), also known as Buna-S, was first manufactured to replace the natural rubber in tires. 90% of the world’s rubber consumption is either natural rubber or SBR. Though similar to natural rubber, SBR is more advanced when it comes to water, heat, and abrasion resistance, as well as low-temperature flexibility and heat aging properties.
SBR is used most commonly in tires, as well as tubes, gaskets, belts, hoses, seals, and other applications where water, brake fluid, and certain alcohols are present.
Silicone rubber is a synthetic rubber with excellent resistance to high temperatures, ozone, oxygen, UV light, moisture, and fungus. Its weaknesses include poor tensile strength, tear resistance, and abrasion resistance.
Thanks to its temperature resistance, silicone is often used in applications that include high or low temperatures. Its long service life also makes it appropriate for industrial applications, including gaskets, seals, o-rings, and bellows.
Best Water Resistance Capabilities
As you can see, these rubbers and elastomers all have their strengths and limitations. If water resistance is your top priority, look to butyl, EPDM, and silicone as solutions.
Butyl rubber is extremely resistant to gas, water, and steam permeation. Butyl rubber is readily available as an elastomeric waterproofing membrane or tape. If you need water resistance, butyl adhesives, liners, and seals should be at the top of your list.
Butyl adhesives are less temperature-sensitive than natural rubber.
EPDM is a completely weather-resistant and UV-resistant synthetic rubber, making it an excellent choice for rubber waterproofing. It maintains its flexibility and strength through extreme high and low temperatures, making it a versatile choice for both static and dynamic applications.
If you need a waterproof material for a static application, that will also be temperature, ozon, and oxygen resistant, look to silicone rubber. Silicone is also a long-lasting material, excellent for industrial applications.
Learn More About Rubber & Elastomers
Discover the best water-resistant rubber or elastomer for your application. Learn more about rubber. The experts at ACE Products and Consulting are here to help and share their expertise.
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