Selecting the appropriate elastomer is crucial for ensuring the performance, durability, and suitability of rubber components in specific applications. Below is a detailed overview of various elastomer types, their properties, and typical applications:
Commonly known as Nitrile or Buna-N, this elastomer is a copolymer of butadiene and acrylonitrile. It is inherently resistant to hydraulic fluids, lubricating oils, transmission fluids, and other non-polar petroleum-based products due to its polar structure. Nitrile also exhibits resistance to air and water environments.
Hydrogenated Nitrile Butadiene Rubber (HNBR) is produced by hydrogenating standard nitrile rubber. This process enhances its resistance to heat, ozone, and aging, while maintaining good mechanical properties. HNBR is suitable for applications involving exposure to oils, fuels, and high-temperature environments.
Blending Nitrile rubber with Polyvinyl Chloride (PVC) enhances ozone and weather resistance. These blends offer improved flexibility, flame resistance, and resistance to oils and chemicals, making them suitable for automotive and industrial applications.
Fluorocarbon elastomers are highly fluorinated, carbon-backboned polymers used to resist harsh chemical and ozone attack, with thermal stability up to 500°F (262°C). They offer low compression set and excellent aging characteristics, providing excellent service in oil, gasoline, hydraulic fluids, hydrocarbon solvents, and extended fuels.
EPDM is known for its excellent resistance to weathering, ozone, and aging. It performs well in brake fluids, steam, water, and phosphate ester-type hydraulic fluids. However, EPDM is not suitable for applications involving exposure to petroleum-based oils and fuels.
SBR is a general-purpose elastomer with properties similar to natural rubber but with improved abrasion resistance. It is commonly used in tires, gaskets, and seals. However, SBR has limited resistance to ozone, sunlight, and oils.
Also known as Neoprene, Polychloroprene is alkali and acid-resistant, flame-retardant, and suitable for petroleum-based oils. It is noted for good compression set resistance, excellent flex fatigue resistance, and resistance to weather and ozone. Its excellent adhesion to metals makes it ideal for molding with metal inserts. However, Polychloroprene is not effective in aromatic and oxygenated solvent environments.
Commonly known as Butyl rubber, IIR is characterized by its low permeability to gases and excellent resistance to heat, weathering, and ozone. It is suitable for applications such as inner tubes, seals, and diaphragms.
Silicone elastomers are known for their wide temperature range and biocompatibility. They offer excellent resistance to weathering, ozone, and aging, making them suitable for medical devices, automotive applications, and consumer products. However, silicones have lower tensile strength and tear resistance compared to other elastomers.
Fluorosilicone combines the wide temperature range of silicone with improved fuel and oil resistance. It is suitable for aerospace and automotive applications where exposure to fuels and extreme temperatures is common.
Polyacrylate elastomers offer excellent resistance to heat, oil, and oxidation. They are commonly used in automotive applications such as transmission seals and hoses. However, they have limited low-temperature flexibility and are not suitable for exposure to water or glycol-based fluids.
Ethylene Acrylic elastomers provide a balance between heat and oil resistance, with good low-temperature flexibility. They are used in automotive applications like hoses and seals. However, AEM is not suitable for exposure to fuels or aromatic hydrocarbons.
CSM, known for its excellent resistance to ozone, weathering, and chemicals, is used in applications such as hoses, seals, and cable jackets. It also offers good flame resistance and color stability.
Epichlorohydrin elastomers provide good resistance to oils, fuels, and ozone, with low gas permeability. They are used in automotive fuel systems, diaphragms, and seals. However, ECO has limited heat resistance compared to other elastomers.
Synthetic Polyisoprene offers similar properties to natural rubber, including high elasticity and good tensile strength. It is used in applications like seals, gaskets, and medical devices. However, it has limited resistance to ozone, weathering, and oils.
Polyurethanes are noted for outstanding resistance to abrasion and tear, providing the highest available tensile strength among all elastomers while offering good elongation characteristics. They are suitable for environments involving ozone, oxidation, sunlight, weather, oil, and incidental gasoline exposure. Polyether-based polyurethanes (EU) are directed toward low-temperature flexibility applications.
Polybutadiene rubber is recognized for its high resilience, excellent abrasion resistance, and low hysteresis loss, which contributes to reduced heat build-up. These properties make it ideal for applications such as tire treads, conveyor belts, and footwear soles. However, BR has limited resistance to ozone and weathering, often necessitating the use of additives or blending with other elastomers to enhance its environmental durability.
Selecting the appropriate elastomer or specialized compound is critical to ensuring the performance, durability, and compliance of rubber components in their intended applications. Consulting with material science experts can aid in making informed decisions tailored to specific operational requirements.
In addition to standard elastomers, specialized compounds are formulated to meet specific industry requirements and certifications:
These are designed to reduce friction and wear in dynamic applications, extending the service life of components such as seals and gaskets.
Compounds compliant with FDA standards are used in applications where rubber components come into contact with food or beverages, ensuring safety and non-toxicity.
Materials that meet Underwriters Laboratories (UL) standards for flammability and safety are essential in electrical and consumer product applications.
Compounds certified for use in potable water systems ensure that no harmful substances leach into drinking water.
Beyond NSF, materials may need to comply with other international standards for potable water applications, depending on the region of use.
Compounds resistant to chlorine and similar chemicals are crucial for components used in swimming pools, water treatment facilities, and other environments where such exposure is common.
These high-performance elastomers offer exceptional chemical resistance and thermal stability, suitable for extreme environments in industries like chemical processing and oil & gas.
Medical-grade compounds are formulated to meet stringent biocompatibility and purity standards for use in medical devices and laboratory equipment.
In applications where the rubber component must not impart any taste or odor, specialized compounds are used to maintain the purity of the product, such as in food and beverage or pharmaceutical industries.
Fluoroelastomer compounds are tailored for high resistance to fuels, chemicals, and high temperatures, making them suitable for seals and gaskets in aggressive environments.
Elastomers used in computer and electronic applications are formulated to provide properties like electromagnetic interference (EMI) shielding, static dissipation, and resistance to outgassing.
