| Nitrile (NBR)Oil resistant rubber. Grades with high acrylonitrile content have better oil resistance whereas low acrylonitrile content gives better low temperature flexibility and resilience. Nitrile has moderate physical properties but good abrasion resistance. Gas permeability is low.Ozone resistance and electrical properties are poor. Flame resistance is poor and it is not suitable for use with use with polar solvents (e.g. MEK).Typical applications include accumulator bladders, diaphragms, gaskets, hose, liners, O-rings and seals.
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| Natural Rubber (NR)Tensile strength, elongation and abrasion resistance is excellent over a wide hardness range, and with the exception of certain formulations of polybutadiene, it has the highest resilience of all rubbers. With its good tear strength, fatigue resistance and excellent compression set it is the ideal choice for dynamic applications at low and ambient temperatures. Weathering resistance is good for black compounds but only fair for white and coloured mixes.Although natural rubber can be used with water and some dilute acids, alkalis and chemicals, EPDM is normally preferable for most aqueous applications. Natural rubber compounds are not suitable for exposure to petroleum based oils and fuels. It has poor resistance to elevated temperatures and is susceptible to attack by ozone unless specifically compounded with anti-ozonants.Typical applications include anti-vibration mounts, drive couplings, haul-off pads and tyres.
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| Hydrogenated Nitrile (HNBR)They have rather better oil and chemical resistance than Nitrile Rubber and can withstand much higher temperatures. HNBR has excellent resistance to sour oil and gas, steam, hot water and ozone. Physical properties (e.g. tensile and tear strength, elongation, abrasion resistance, compression set, etc.) are also excellent and compounds exhibit good dynamic behaviour at elevated temperatures.Limitations include poor electrical properties, poor flame resistance and attack by aromatic oils and polar organic solvents.Typical applications include accumulator bladders, diaphragms, gaskets and seals, especially for the oil and gas industries.
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| Fluoroelastomer (FKM) – Viton®Most suitable rubbers for continuous use at temperatures of 200°C and up to 300°C for short periods. Various grades are available depending upon whether compression set, flexibility (as in diaphragms) or chemical resistance is the prime concern. Fluoroelastomers have excellent resistance to ozone and weathering, oils and most chemicals.They are, however, very expensive, unsuitable for use with phosphate esters and ketones and have poor low temperature capabilities.Typical applications include accumulator bladders, diaphragms, gaskets, O-rings and seals operating in especially harsh environments.
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| Ethylene Propylene (EPDM)Excellent heat, ozone and chemical resistance. Physical properties are very good and resistance to polar fluids is generally good. Low temperature resistance is very good and EPDM can be compounded to give excellent electrical resistance.EPDM is not suitable for exposure to petroleum based fluids and di-ester lubricants.Typical applications include accumulator bladders, cable connectors and insulators, diaphragms, gaskets, hoses and seals.
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| Chlorosulfonated Polyethylene (CSM) – Hypalon®Better heat ageing, chemical resistance and excellent low gas permeability. Ozone and weathering resistance is also excellent and electrical properties are good. Low temperature flexibility and oil resistance is similar to chloroprene.Hypalon has poor fuel resistance and dynamic sealing applications are not recommended in view of its poor compression set.
Typical applications include static seals and any components likely to suffer hot and humid weather conditions or exposure to hot liquids and gases.
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| Butyl (IIR)Has exceptionally low gas permeability making it ideal for inner tubes and high pressure/vacuum sealing applications. It’s very low resilience makes it suitable for shock and vibration damping. Its chemical unsaturation gives it excellent resistance to heat, ozone, and weathering, and also to dilute acids and alkalis.It is not suitable for use in mineral or petroleum based fluids.Typical applications include diaphragms, gaskets, inner tubes, liners, O-rings, seals, speaker surrounds and bottle closures.
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| Styrene Butadeine (SBR) Its physical strength, resilience and low temperature properties are usually inferior to Natural Rubber though heat-aging properties and abrasion resistance are better.SBR is not resistant to oil or fuel resistant and it can be prone to weathering.Typical applications include drive couplings, haul-off pads, shoe soles/heels and car tyres.
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| Silicone (Q) Silicone Rubbers are ideal for high and low temperature applications. Electrical properties are excellent and resistance to weathering and ozone attack is outstanding.It is not resistant to super-heated steam. Physical properties are generally low but are at least retained at higher temperatures. Gas permeability is very poor as is resistance to petroleum based fluids. Silicone rubbers are expensive in comparison to most other rubbers.Food Quality/FDA compliant grades are available for use in the food and pharmaceutical industries. Room Temperature Vulcanisation (RTV) grades are also available, usually for prototypes or small batch quantities.
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| Polychloroprene (CR) – NeopreneOil resistant synthetic rubbers. However, it has only moderate resistance to petroleum based oils and fuels. It can be considered as a good general purpose rubber with an excellent balance of physical and chemical properties. It has better chemical, oil, ozone and heat resistance than natural rubber but a rather lower level of physical properties.Typical applications include belting, coated fabrics, cable jackets, seals and gaiters. |
Viton® and Hypalon® are registered trademark of DuPont Performance Elastomers L.L.C.