GENERAL ELAST0MERIC PROPERTIES
Natural Rubber
Two types are most commonly used-smoked sheets and pale crepe. They are alike except in color and odor. Pale crepe is used for light colors and when odor is objectionable. Both possess exceptional elastic qualities and have good resistance to water and acids. They are compatible with synthetic rubbers and are often used in blends.

C.R. Chloroprene Rubber
(Neoprene) Resists fats and oils and petroleum products. Stands up well in sunlight.

Polyisoprene
A substitute for natural rubber and has very similar characteristics.

Styrene Butadiene Rubbers (SBR)
Synthetic substitutes for natural rubber.

Isoprene-Isobutylene Rubber (I.I.R., Butyl)
Has excellent resistance to aging, heat, sunlight and ozone.

Chlorinated Butyl (Chlorobutyl)
Exceptional heat stability, low compression set, low permeability to gasses and good resistance to chemicals, oxidation and tearing.

Nitrile Butadiene Rubber (N.B.R., Buna N, Hycar, Chemigum, Krynac, etc.)
This is the oil-resistant Buna. Can be compounded for particular applications, so that it will either shrink slightly or swell up on immersion in oil.

Polyacrylic
High oil resistance and dry heat resistance up to 350'F

Epichlorohydrin (Hydrin)
Ozone resistance, broad temperature range and oil resistance.

Thiokol Polysulfide
More inert than most synthetics. High resistance to oil, gasoline and aromatic solvents-lacquer thinners.

Silicone and Fluoro-Silicone Rubber
High and low temperature stability, exceptional release from sticking, resistance to aging, ozone and sunlight, good dielectrics and outstanding water repellency.

Millable Urethanes
Exceptional tensile strength. Abrasion and low temperature resistance.

Hypalon¨
High ozone and corona resistance, heat resistance up to 300'F and good color stability

Fluoro Elastomers (Viton¨, Flourel)
For extreme heat resistance-temperatures ranging to +500'F Resistance to abrasion, oil and chemicals is outstanding. Good resistance to ozone, weathering and flame.

Polybutadiene
Excellent abrasion resistance. Good low temperature qualities.

Ethylene Propylene Copolymer (E.R M.)
Resistance to chemicals, chemical solutions, heat and ozone.

Ethylene Propylene Diene Terpolymer (E.R D.M.)
Excellent in water, steam, heat, weather, detergents, ozone and many chemicals.

TFE Propylene (Aflas)
Has an advantageous combination of chemical, electrical, and high temperature resistance properties.

PTFE (polytetrafluoroethylene) Teflon¨
This compound is impervious to virtually all fluids and gasses ranging from -320'F to 450'F Only molten alkaline metals and certain halogenated compounds will attack it.

TEMPERATURE RANGE CHART
The temperature range for any compound is determined by the base elastomer used. This chart depicts the maximum temperature range for each elastomer. The temperature range for a specific compound may not reach these maximum limits. Higher temperatures may be considered if exposure is short term or intermittent



DUROMETER CHART

The hardness of rubber compounds is measured by the Shore A durometer; the higher the durometer number, the harder the compound. 70-durometer hardness should be used wherever possible as it offers the best combination of properties for most o-ring applications. Softer compounds stretch easier and seal better on rough surfaces. Harder compounds offer greater abrasion resistance and resistance to extrusion. Extrusion must always be considered when high pressures are used. The proper hardness may be selected from this chart by matching the fluid pressure with the maximum extrusion gap.

C0MPARIS0N 0F PR0PERTIES CHART
This chart matches the general rubber properties required in most o-ring applications with the capabilities of commonly used elastomers. Since no one elastomer is rated "excellent" for all properties, compromises are sometimes necessary when selecting an elastomer for a specific o-ring application. Start with the most critical properties to narrow your choices.