Butyl Rubber (IIR) O-Rings

Butyl (IIR) Isoprene® O-Rings Material Description

Butyl (IIR) Isoprene® is a copolymer composed of isobutylene and a little bit of isoprene. The isoprene are double-bonded to provide cross-linking during vulcanization. Butyl offers outstanding resistance to heat aging, ozone/weather, chemical attack, abrasion and tearing and is gas impermeable. Excellent electrical insulation performance. Recommended for general purpose applications, vacuum, and low compression set.

Engineered Seal Products has the expertise and inventory for your butyl (IIR) o-ring applications. For over 50 years, ESP has been the leading engineering, quality, and supply chain choice for both standard and custom sealing applications. A seal, no matter the application, has to do just that.

Also Know As:

Butyl, IIR, Isoprene®, Exxon Butyl®, Polysar Butyl®, Esso Butyl®

Butyl (IIR) Isoprene® Advantages:
  • Heat aging resistance
  • Ozone / Weather resistance
  • Chemical attack resistance
  • Abrasion and tearing resistance
  • Gas impermeable

Excellent electrical insulation performance.

Butyl (IIR) Isoprene® Disadvantages:

Incompatible for applications that come in contact with:

  • Mineral oil and grease.
  • Fuels.
  • Chlorinated hydrocarbons.

Butyl (IIR) Isoprene® Material Properties

Butyl (IIR) Material Temperature Range:

Heat Resistance: Up to approximately 250°F (121°C)

Cold Flexibility: Down to approximately -75°F (-59°C).

Normal Recommended Temperature Range Normal recommended temperature range

Extended Temperature Range Extended Temperature Range for short term only

PDF O-Ring Temperature Range Chart

Abrasion Resistance Fair/Good
Chemical Resistance Excellent
Cold Resistance Good
Heat Resistance Good
Oil Resistance Poor
Ozone Resistance Good/Excellent
Tensile Strength Good
Water/Steam Resistance Good

Material properties & Temp ranges based on Parker o-Ring Handbook (ORD 5700) recommendations.

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ASTM Designation
Shelf Life
15 Years
Hardness (Shore A) Range
30 - 90

Temperature ranges will apply to the majority of media for which the material is potentially recommended. With some media however, the service temperature range may be significantly different. ALWAYS TEST UNDER ACUTAL SERVICE CONDITIONS.

ESP’s shelf life recommendation is based on the ARP 5316 standard and intended to be utilized by those organizations who do not already have specific recommendations for the control of elastomeric seals. It should be noted that the packaging of the elastomeric seals prior to assembly into a product is an integral part of the controlled storage procedure. It provides a positive means of product identity from the time of manufacture, to the time of assembly.