Rubber Material Types for Rubber Seals, Rubber Gaskets and O rings
Materials Technologists are constantly developing new seal materials to meet the increasing demands of today’s engineering applications.
IIR
Resistant to the same fluid types as EPDM , the distinctive properties of IIR rubber materials are very low gas and moisture permeability, excellent insulating properties, good ozone and weathering resistance, and resistance to a great many organic and inorganic media. IIR elastomer materials can be polymerised with various halogens (e.g. Chlorine / Bromine) to improve resistance to certain chemical media, but at the expense of electrical insulation and moisture resistance. They can be used from –40 to +120°C typically, and are mostly used in the production of tyre inner tubes, seals and rubber gaskets, vacuum seals and membranes, and pharmaceutical goods.
CR
CR seal materials typically display good resistance to ozone, heat aging and chemicals. Good resistance to refrigerants, aliphatic hydrocarbons, mineral oils and greases. Typical trade name: Neoprene® (Dupont Dow Elastomers)
Chlorobutadiene rubbers contain chlorine in the polymer to reduce the reactivity to many oxidising agents, as well as to oil and flame. CR elastomers also have good resistance to ozone cracking, heat ageing and chemical attack. Some of the important applications of CR elastomers include Vee-belts, coated fabrics, cable jackets, tyre-sidewalls, seals and gaskets in contact with refrigerants, mild chemicals and atmospheric ozone.
CSM
CSM grades contain 24-43% chlorine content to provide excellent ozone and weather resistance, discoloration by sun and ultraviolet light, high resistance to many oxidising and corrosive chemicals, good resistance to dry heat to 150°C, low flammability and gas permeability, and also good resistance to hot water (when cured with lead oxide). The low temperature properties are generally limited, depending on the chlorine content of the CSM grade used, and the compression set is not very good. CSM elastomers are generally useful in electrical applications, weather resistant membranes, hoses and acid resistant tank linings.
ECO
Generally resistance to high temperatures, oils, ozone, and flame with gas resistance comparable to NBR’s. The temperature range for continuous use is –40 to +120°C, but are generally unsuitable for rubber to metal bonding (they are corrosive to metals). ECO elastomers are suitable for use in seals, gaskets, diaphragms, cable jackets, belting etc, for a wide range of media. However, they are unsuitable for use with ketones and esters, alcohols, phosphate ester hydraulic fluids, sour gas, water and steam.
AEM
AEM rubber materials offer an unusual combination of physical properties; high heat resistance (up to 175°C), excellent ozone and weather resistance, moderate resistance to mineral oils, low temperature flexibility to –30°C, good resistance to hot water and high tensile strength. AEM applications are similar to ACM elastomers, but has the advantage where low temperature flexibility is concerned. They are typically moulded into O rings seals, boots and ignition wire jackets.