What is synthetic rubber?
Synthetic rubber is an artificial copolymer produced through chemical reactions known as condensation or polymerisation, based on certain unsaturated hydrocarbons.
These are some of the main synthetic rubbers used in the production of our gaskets:
NBR (Acrylonitrile-Butadiene Rubber)
NBR is the most widely used material due to its excellent mechanical properties, high resistance to abrasion, low permeability to gases and high resistance to mineral oils and greases. NBR is a butadiene and acrylonitrile coploymer. Depending on the use, the acrylonitrile content can vary between 18% and 50%.
NBR O-rings are perfectly compatible with countless water and air applications and withstand temperatures of between -20 to +100/+120 °C.
FPM-Viton® is a fluoroelastomer obtained from the derivation of synthetic rubber and elastomer fluoropolymer. The main advantages of Viton® as a material can be summarised in that it possesses high resistance to very aggressive fluids, good resistance to deformation, excellent retention of sealing force and of the original hardness of the design.
FPM-Viton® O-rigns ensure greater elasticity and resistance than other types of rubber. This type of gasket provides excellent compression set at high temperatures as they resist from -20 to +200/+220 ºC.
EPDM (Ethylene Propylene Diene)
Ethylene propylene diene rubber or EPDM is an elastomer thermopolymer that provides good resistance to abrasion and wear. The composition of this material usually contains between 45% and 75% of ethylene; the higher this percentage, the greater the resistance.
EPDM O-rings can be used in a wide range of temperatures (from -30 ºC to +110/+130 ºC), possess good resistance to ozone, the elements and aging, and are resistant to hot water and steam. Moreover, they are good electrical insulators.
VMQ (Vinyl Methyl Polysiloxane)
The term silicone includes a large group of materials of which VMQ (vinyl-methyl-silicone) is one. Silicone is a polymer that is formed by a chemical combination of inorganic and organic bonds. Silicone elastomers have many useful properties, the most noteworthy of which are good heat resistance and good cold flexibility. They also have good resistance to ozone and ageing, as well as good insulating and physiologically neutral properties.
Due to their relatively low tear resistance and high friction coefficient, VMQ O-rings are not recommended for dynamic sealing applications. Their temperature range lies between -60 to + 160/+180 ºC.
FFKM (Fluorocarbon Elastomer)
Also known as perfluoroelastomer, this material contains higher amounts of fluorine than standard FKM, and withstands higher temperatures, up to around 300 °C. FFKM also improves chemical resistance, with almost universal chemical compatibility. This is an ideal material for the chemical, food and medicine industries, although it is also used in the production of oil and gas.
The resistance of FFKM O-rings to chemicals is almost as universal and comparable as that of PTFE. The wide range of temperatures FFKM O-rings are capable of withstanding goes from -15 to +320 °C, and the range is even greater in the case of FFKM Evolast® O-rings: from -25 °C to 270 °C for standard grades, and up to 340 °C for higher grades.
HNBR (Hydrogenated Nitrile Butadiene Rubber)
Also known as Highly Saturated Nitrile (HSN) or Hydrogenated Nitrile, this is a special kind of Nitrile rubber (NBR) that has been hydrogenated to increase the saturation of the butadiene segment of the carbonic polymer foundation.
HNBR O-rings feature both the characteristics of NBR and also have a higher degree of resistance to heat, chemicals and ozone than NBR. Hydrogenated nitrile performs extremely well when used in dynamic operations, and as such HNBR gaskets possess excellent mechanical resistance and tensile resistance.
HNBR O-rings are capable of withstanding a wide range of temperatures, from -5 ºC to +150 ºC, and possess excellent chemical resistance, making them the ideal gaskets for the oil and gas industries.
This synthetic rubber, produced through the polymerisation of chloroprene, is also known as Chloroprene or Neoprene CR. It features good flexural resistance, excellent fatigue resistance, and good resistance to the elements and ozone. This synthetic rubber is ideal for general use in industry and construction.
CR O-rings possess good mechanical characteristics even with low loads, and as with natural rubber it has good resistance as of 60 degrees Shore A, medium resistance to hydrocarbons, oxygen and ozone.
The chemical and physical properties of CR gaskets are similar to those of NBR. Resistance to mineral oils is slightly lower, but resistance to ageing, ozone, acids and alkalis is excellent. The temperature range for CR rubber is –40 °C to +120 °C.
Polyacrylic elastomers, also known as ACM rubber, are synthetic polar types of rubber composed of acrylic monomers, generally manufactured through emulsion or suspension polymerisation.
ACM O-rings are often used when combined resistance to heat and oils is required. Hence, they are a good alternative to more expensive heat-resistant elastomers such as FKM, VMQ and FVMQ gaskets and have an operating temperature range of -10 °C to +200 °C.
Fluorosilicone is the material that arises from the combination of fluoroelastomer (FKM) and silicone; in the case of FVMQ it is obtained by mixing trifluoropropyl, methyl and vinyl.
This material features exceptional heat resistance, which is why FVMQ O-rings are among the most commonly used in the production of turbocharger hoses and gaskets in the automotive sector.
The resistance of these gaskets to a wide range of temperatures (ranging from -60 to +200 °C) and to the action of aggressive products (gasoline, alcohol mixtures, aromatic oils, naphthenic oils, chlorinated solvents …), makes them a good choice.
IIR (Butyl Isobutylene Isoprene)
Butyl rubber is the synthetic elastomer arising from the copolymerisation of isobutylene and isoprene, known by the international abbreviation IIR (Isobutylene Isoprene Rubber).
IIR O-rings ensure both excellent resistance to the elements, oxidation, ozone and heat and very low resilience, which provides non-sustained impact and vibration damping properties.