Material Choice Guide to Selecting Rubber Compounds

24 Jun.,2024

 

Material Choice Guide to Selecting Rubber Compounds

Nitrile Acrylonitrile-butadiene rubber NBR NBR Buna-N BF, BG, BK, CH Hydrogenated Nitrile Hydrogenated Acrylonitrile-butadiene rubber
HNBR (HNBR) HNBR DH Ethylene-Propylene Ethylene propylene diene rubber EPDM EPDM EP, EPT, EPR BA, CA, DA Fluorocarbon Fluorocarbon Rubber FKM FPM Viton ®, Fluorel ® HK Chloroprene Chloroprene rubber CR CR Neoprene BC, BE Silicone Silicone rubber VMQ VMQ PVMQ FC, FE, GE Fluorosilicone Fluorosilicone rubber FVMQ FVMQ FVMQ FK Polyacrylate Polyacrylate rubber ACM ACM ACM EH Ethylene Acrylic Ethylene Acrylic rubber AEM AEM Vamac ® EE, EF, EG, EA Styrene-butadiene Styrene-butadiene rubber SBR SBR SBR AA, BA Polyurethane Polyester urethane / Polyether urethane AU / EU AU / EU AU / EU BG Natural rubber Natural rubber NR NR NR AA Very Good = 1 Good = 2 Average = 3 Poor = 4 Temperature in °F Basic Property NBR HNBR EPDM FKM CR ACM AEM SBR AU/EU VMQ FVMQ NR Economy of Material 1 4 2 3 2 3 4 1 3 3 4 1 Compression Set Resistance 1 1 1 1 2 4 2 2 3 2 2 1 Resilience (Rebound) 2 2 2 2 2 3 2 2 2 2 2 1 Tear Strength 2 1 2 2 2 3 2 3 2 4 3 1 Heat Aging Resistance 3 2 2 1 3 1 1 3 1 1 1 3 Ozone Resistance 4 2 2 1 2 2 1 4 1 1 1 4 Resistance to Oil & Grease 2 2 4 1 2 1 3 4 2 3 1 4 Fuel Resistance 4 3 4 2 4 1 4 4 3 4 2 4 Water Swell Resistance 2 2 1 2 3 4 2 1 4 1 1 1 Gas Impermeability 2 2 3 2 2 3 2 3 2 4 4 3 Dynamic Service / Abrasion Res. 2 2 2 3 2 2 2 1 1 4 4 1 High Temperature - Standard 212 300 300 390 250 300 300 212 175 450 400 220 High Temperature - Special 250 - - - - - - - - 480 - - Low Temperature - Standard -22 - 22 -60 5 -40 -60 -40 -50 -60 -75 -75 -60 Low Temperature - Special -60 -40 - -30 - - - - - - - - NATURAL RUBBER (NR) Natural rubber is a product coagulated from the latex of the rubber tree, hevea brasiliensis. Natural rubber features low compression set, high tensile strength, resilience, abrasion and tear resistance, good friction characteristics, excellent bonding capabilities to metal substrate, and good vibration dampening characteristics. Temperature Range (dry heat) low high - 60 °F
-51 °C 220 °F
104 °C Application Advantages » excellence compression set
» good resilience and abrasion
» good surface friction properties



Primary Uses Application Disadvantages O-rings, rubber seals and custom molded rubber components for:
» rubber to metal bonded vibration isolators and mounts
» automotive diaphragms
» FDA applications for food and beverage seals

» poor resistance to attack by petroleum oils
» poor ozone, UV resistance

FLUOROSILICONE (FVMQ) Fluorosilicones combine most of the attributes of silicone with resistance to petroleum oils and hydrocarbon fuels.
Low physical strength and abrasion resistance combined with high friction limit fluorosilicone to static seals.
Fluorosilicones are used primarily in aircraft fuel systems. Temperature Range (dry heat) low high -75 °F
-59 °C 450 °F
232 °C Application Advantages » excellent extreme temperature properties
» excellent compression set resistance
» very clean, low odor and taste


Primary Uses Application Disadvantages O-rings, rubber seals and custom molded rubber components for:
» seals (static) for extreme temperature applications
» food applications
» medical devices
» FDA applications
» typically not good for dynamic seals due to friction properties and poor abrasion resistance
SILICONE (VMQ) Silicone is a semi-organic elastomer with outstanding resistance to extremes of temperature with corresponding resistance to compression set and retention of flexibility. Silicone elastomers provide excellent resistance to ozone, oxygen, and moisture.
Low physical strength and abrasion resistance combined with high friction properties limit silicone to static seal applications.
Silicone utilizes a flexible siloxane backbone rather than a carbon backbone like many other elastomers and has very low glass transition temperatures. Temperature Range (dry heat) low high -75 °F
-59 °C 450 °F
232 °C Application Advantages » excellent extreme temperature properties
» excellent compression set resistance
» very clean, low odor and taste

Primary Uses Application Disadvantages O-rings, rubber seals and custom molded rubber components for:
» seals (static) for extreme temperature applications
» food applications
» medical devices
» FDA applications » typically not good for dynamic seals due to friction properties and poor abrasion resistance POLYURETHANE (AU) (EU) Millable polyurethane exhibits excellent abrasion resistance and tensile strength as compared to other elastomers providing superior performance in hydraulic applications with high pressures, abrasive contamination and shock loads. Fluid compatibility is similar to that of nitrile at temperatures up to approximately 175 °F. At higher temperatures, polyurethane has a tendency to soften and lose both strength and fluid resistance advantages over other elastomers. Temperature Range (dry heat) low high - 60 °F
- 51 °C 175 °F
79 °C Application Advantages » excellent strength and abrasion resistance
» good resistance to petroleum oils
» good weather resistance
Primary Uses Application Disadvantages O-rings, rubber seals and custom molded rubber components for:
» seals for high hydraulic pressure
» highly stressed parts subject to wear

» poor resistance to water
» poor high temperature capabilities



STYRENE BUTADIENE (SBR) Styrene-Butadiene (SBR) is a copolymer of styrene and butadiene.
SBR compounds have properties similar to those of natural rubber. SBRs primary custom molded application is the use in hydraulic brakes system seals and diaphragms, with the major of the industry usage coming from the Tire Industry.
SBR features excellent resistance to brake fluids, and good water resistance. Temperature Range (dry heat) low high - 50 °F
-46 °C 212 °F
100 °C Application Advantages » good resistance to brake fluids
» good resistance to water
Primary Uses Application Disadvantages O-rings, rubber seals and custom molded rubber components for:
» hydraulic brake systems seals and diaphragms
» plumbing applications
» poor weather resistance
» poor petroleum oil and solvent resistance


ETHYLENE ACRYLIC (AEM) Ethylene-acrylic (Vamac ®) is a terpolymer of ethylene, methyl acrylate, and an acid-containing monomer as a cure site. It exhibits properties similar to those of Polyacrylate, but with extended low temperature range and with enhanced mechanical properties.
Ethylene-acrylic offers a high degree of oil, ozone, UV and weather resistance. Temperature Range (dry heat) low high - 40 °F
- 40 °C 300 °F
149 °C Application Advantages » excellent vibration dampening
» excellent heat aging characteristics
» good dynamic property retention over a wide temperature range
» resistance to transmission fluids, water, glycol mixtures, and alkalies Primary Uses Application Disadvantages O-rings, rubber seals and custom molded rubber components for:
» Automotive sealing applications.
» Automotive transmissions
» Power steering seals
» not recommended for exposure to fuel, brake fluid, aromatic hydrocarbons or phosphate esters.

POLYACRYLATE (ACM) Polyacrylates are copolymers of ethyl and acrylates which exhibit excellent resistance to petroleum fuels and oils and can retain their properties when sealing petroleum oils at continuous high temperatures up to 300 °F. These properties make polyacrylates suitable for use in automotive automatic transmissions, steering systems, and other applications where petroleum and high temperature resistance are required.
Polyacrylates also exhibit resistance to cracking when exposed to ozone and sunlight.
Polyacrylates are not recommended for applications where the elastomer will be exposed to brake fluids, chlorinated hydrocarbons, alcohol, or glycols. Temperature Range (dry heat) low high -60 °F
-51 °C 300 °F
149 °C Application Advantages » petroleum fuel and oil resistance
» resists flex cracking
» good ozone resistance
» good heat resistance Primary Uses Application Disadvantages O-rings, rubber seals and custom molded rubber components for:
» Automotive transmissions.
» Automotive steering systems
» poor compression set performance relative to NBR
» lesser water resistance and low temperature performance than some other elastomers
NEOPRENE / CHLOROPRENE (CR) Neoprene homopolymer of chlorobutadiene and is unusual in that it is moderately resistant to both petroleum oils and weather (ozone, UV, oxygen). This qualifies neoprene uniquely for certain sealing applications where many other materials would not be satisfactory. Neoprene is classified as a general purpose elastomer which has relatively low compression set, good resilience and abrasion, and is flex cracking resistant.
Neoprene has excellent adhesion qualities to metals for rubber to metal bonding applications.
It is used extensively for sealing refrigeration fluids due to its excellence resistance to Freon® and ammonia. Temperature Range (dry heat) low high - 40 °F
- 40°C 250 °F
121°C Application Advantages » moderate resistance to petroleum oils
» good resistance to ozone, UV, oxygen
» excellence resistance to Freon® and ammonia
Primary Uses Application Disadvantages O-rings, rubber seals and custom molded rubber components for:
» refrigeration industry applications
» general purpose seals, hose and wire » moderate water resistance
» not effective in solvents environments FLUOROCARBON (FKM) Fluorocarbon exhibits resistance to a broader range of chemicals combined with very good high temperature properties more so than any of the other elastomers. It is the closest available approach to a universal elastomer for sealing in the use of o-rings and other custom seals over other types of elastomers.
Fluorocarbons are highly resistant to swelling when exposed to gasoline as well as resistant to degradation due to expose to UV light and ozone.
When exposed to low temperatures, fluorocarbon elastomers can become quite hard (-4 °F) but can be serviceable at low temperatures, although FKM compounds are not recommended for applications requiring good low temperature flexibility.
In addition to standard FKM materials, a number of special materials are available with differing monomer compositions and fluorine content (65% to 71%) for improved low temperature, high temperature, or chemical resistance performance.
Fluorocarbons exhibit low gas permeability making them well suited for hard vacuum service and many formulations are self-extinguishing. FKM materials are not generally recommended for exposure to hot water, steam, polar solvents, low molecular weight esters and ethers, glycol based brake fluids, or hot hydrofluoric or chlorosulfonic acids. Temperature Range (dry heat) low high 5 °F
- 15 °C 390 °F
199 °C Application Advantages » excellent chemical resistance
» excellent heat resistance
» good mechanical properties
» good compression set resistance Application Disadvantages » poor low temperature flexibility
» poor resistance to hot water and steam Modifications » differing monomer compositions and fluorine content (65% to 71%) for improved low temperature, high temperature, or chemical resistance performance
Primary Uses Specialized Applications O-rings, rubber seals and custom molded rubber components for
» Automotive fuel handling
» Aircraft engine seals
» High temperature applications requiring good compression set
» General industrial seals and gaskets » degree of fluorination (A, B, F, GB, GF, GFLT, GBLT, GLT, ETP)
» copolymer or terpolymer of fluorinated hydrocarbon monomers
ETHYLENE-PROPYLENE (EPDM) Ethylene-propylene compounds are prepared from ethylene and propylene (EPM) and usually a third monomer (EPDM). These compounds are used frequently to seal in brake systems, and for sealing hot water and steam.  Ethylene propylene compounds have good resistance to mild acids, detergents, alkalis, silicone oils and greases, ketones, and alcohols. They are not recommended for applications with petroleum oils, mineral oil, di-ester lubricants, or fuel exposure.

Ethylene Propylene has gained wide seal industry acceptance for its excellent ozone and chemical resistance properties and is compatible with many polar fluids that adversely affect other elastomers.

EPDM compounds are typically developed with a sulfur or peroxide cure system. Peroxide-cured compounds are suitable for higher temperature exposure and typically have improved compression set performance. Temperature Range (dry heat) low high -60 °F
-51 °C 300 °F
149 °C Application Advantages » excellent weather resistance
» good low temperature flexibility
» excellent chemical resistance
» good heat resistance Application Disadvantages » poor petroleum oil and solvent resistance
Modifications » sulfur-cured and peroxide-cured compounds
» third comonomer EPDM, copolymer ethylene and propylene EPM
Primary Uses Specialized Applications O-rings, rubber seals and custom molded rubber components for:
» Water system seals, faucets, etc.
» Brake systems
» Ozone exposure applications
» Automotive cooling systems
» General Industrial Use » glycol-based brake system seals
» FDA approved applications
» NBR NSF standard 61 for potable water applications
» NBR WRc, KTW water applications HYDROGENATED NITRILE (HNBR) HNBR is created by partially or fully hydrogenating NBR. The hydrogenating process saturates the polymeric chain with accompanying improvements to the ozone, heat and aging resistance of the elastomer and improves overall mechanical properties.
HNBR, like Nitrile, increasing the acrylonitrile content increase resistance to heat and petroleum based oils and fuels, but decreases the low temperature performance. Temperature Range (dry heat) low high -22 °F
-30 °C 300 °F
149 °C Application Advantages » excellent heat and oil resistance
» improved fuel and ozone resistance (approximately 5X) over Nitrile
» abrasion resistance Application Disadvantages » increased cold flow with hydrogenation
» decreased elasticity at low temperatures with hydrogenation over standard nitrile Primary Uses Modifications O-rings, rubber seals and custom molded rubber components for:
» Oil resistant applications
» Oil well applications
» Fuel systems, automotive, marine, and aircraft
» General Industrial Use » acrylonitrile content (ACN) from 18% to 50%
» peroxide vs. sulfur donor cure system
NITRILE (NBR) Nitrile is the most widely used elastomer in the seal industry. The popularity of nitrile is due to its excellent resistance to petroleum products and its ability to be compounded for service over a temperature range of -22°F to 212°F.
Nitrile is a copolymer of butadiene and acrylonitrile. Variation in proportions of these polymers is possible to accommodate specific requirements. An increase in acrylonitrile content increases resistance to heat plus petroleum base oils and fuels but decreases low temperature flexibility. Military AN and MS O ring specifications require nitrile compounds with low acrylonitrile content to insure low temperature performance.
Nitrile provides excellent compression set, tear, and abrasion resistance. The major limiting properties of nitrile are its poor ozone and weather resistance and moderate heat resistance, but in many application these are not limiting factors. Temperature Range (dry heat) low high -22 °F
-30 °C 212 °F
100 °C Application Advantages » excellent compression set,
» superior tear resistance
» abrasion resistance Application Disadvantages » poor weather resistance
» moderate heat resistance Modifications » acrylonitrile content (ACN) from 18% to 50%
» peroxide vs. sulfur donor cure system
» XNBR improved wear resistance formulation Primary Uses Specialized Applications O-rings, rubber seals and custom molded rubber components for:
» Oil resistant applications
» Low temperature applications
» Fuel systems, automotive, marine, and aircraft
» General Industrial Use » NBR NSF standard 61 for potable water applications
» NBR WRc, KTW water applications
» NBR FDA white list compounds

You will get efficient and thoughtful service from xtnbk.

Viton vs Nitrile O Rings

As two of the most commonly used elastomers, both Viton&#; and nitrile o rings have some fantastic properties. Both offer excellent compression set and have a wide range of uses in industrial and domestic applications. However, not everything is equal between these two popular materials, and it&#;s important to know which is better for particular applications. Here, we&#;ll look at Viton&#; vs nitrile o rings to see where each should be used, and why.

Nitrile o-rings

Also called NBR or Buna-N, nitrile o rings are probably the most economical and widely used elastomer out there. This material has a desirable set of properties including low compression set, high resistance to abrasion and good tensile strength.

  • Temperature range: Effective from -40°C to 120°C
  • Suitability: General purpose, particularly in areas where the seal will be exposed to hydrocarbons, oils, petrol, water and hydraulic fluids
  • Benefits: Excellent abrasion and tear resistance, cost effective
  • Limitations: Nitrile is not good at resisting degradation by ozone or weather

You&#;ll find nitrile o rings used in many applications, including where oil resistance is needed or where low temperature functionality is required. These include automotive, aircraft fuel systems, marine applications and more.

Viton&#; o rings

The name Viton is a trademark, a bit like Hoover or Sellotape, and refers to fluorocarbon o rings, or FKM/FPM for short. This material has an excellent tolerance for high temperatures, resistance to oils, fuels and hydraulic fluids as well as aromatics and solvents.

Various types of FKM/FPM/Viton&#; o rings are available, with varying amounts of fluorine additions which increase performance in specific situations.

  • Temperature range: From -40°C up to 250°C
  • Suitability: Good for use in high temperature situations or where chemicals are being used. As well as resisting oils, petrol and hydrocarbons, Viton&#; is resistant to mineral acids, halogenated hydrocarbons and more.
  • Benefits: Resistant to the majority of chemicals, as well as to degradation by UV, weather, ozone and mould.
  • Limitations: Less tolerant of low temperatures

You&#;ll find FKM/FPM o rings in a huge variety of applications from aircraft engines to vehicle components, particularly where resistance to corrosive liquids and fuels is required. This material has low compression set characteristics, making it ideal for use in high temperature environments, as well as resistance to all sorts of chemicals.

Viton&#; vs nitrile o rings &#; which is the right choice?

Viewing these two o ring materials at a glance, it&#;s easy to see some occasions where the decision of Viton&#; vs nitrile o rings will be clear to see. For example, if you know your assembly works at more than 100°C, nitrile will not be suitable. If your assembly is likely to be exposed to the weather, to UV or to ozone, nitrile will likely degrade and risk failure.

Viton&#; /FKM/FPM is superior to nitrile in almost all situations, excluding operation at sub zero temperatures.

If you&#;re not sure which you need in the case of Viton&#; vs nitrile o rings, we&#;re here to help. We&#;ve worked alongside customers from all sorts of diverse industries to help match them up with the right o ring for their needs and can help you too. We want to make sure you get all the functionality you need, without spending more than is necessary. Talk to our experienced team today for advice and support.

For more nbr power steering sealinformation, please contact us. We will provide professional answers.