IIR — Isobutylene Isoprene Rubber

Butyl Rubber

Butyl rubber has the lowest gas permeability of any common elastomer, making it the specialist choice for vacuum, pneumatic, and gas-tight sealing. We stock IIR sheet rubber in standard and bromo-butyl grades with excellent resistance to ozone, weathering, and polar chemicals.

At a Glance

Temperature Range

-50 °C to +120 °C continuous

Thickness Range

1.5 mm to 6 mm

Hardness Range

40–75 Shore A

Brands We Stock

ExxonMobilLANXESS
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Technical Properties

Typical values across stocked grades. Specific grade data sheets available on request.

Temperature Range-50 °C to +120 °C continuous
Hardness (ASTM D2240)40–75 Shore A
Tensile Strength (ASTM D412)7–17 MPa
Elongation at Break (ASTM D412)300–800%
Compression Set (ASTM D395)20–50%. 22 h @ 100 °C
Tear Strength (ASTM D624)15–40 kN/m
Specific Gravity (ASTM D792)1.05–1.25
Thickness Range1.5–6 mm stocked
ASTM D2000 ClassificationAA (Type A heat ageing, Class A)
Gas Permeability (ASTM D1434)Lowest of all common elastomers
Ozone Resistance (ASTM D1171)Excellent. No cracking
Vibration DampingSuperior. Highest damping coefficient of all rubbers

Common Applications

  • Vacuum system gaskets and seals
  • Pneumatic and gas-tight enclosure seals
  • Chemical tank linings — acids and alkalis
  • Pharmaceutical cleanroom seals
  • Ozone-generating equipment gaskets
  • Vibration dampening pads (high damping coefficient)
  • Refrigerant and air conditioning system gaskets
  • Electrical insulation sheets

Available Grades

Brands we stock: ExxonMobil, LANXESS

Standard Butyl (50 Shore A)

General-purpose dark grey butyl sheet with outstanding gas impermeability and excellent resistance to ozone, weathering, and polar solvents. Our standard grade for vacuum and gas-sealing applications.

Bromo-Butyl

Brominated butyl with improved heat resistance and faster cure rates compared to standard IIR. Better compatibility with other rubber compounds in bonded assemblies.

Moulded Butyl

Precision-moulded butyl sheet with tighter hardness and thickness tolerances. Used where consistent sealing performance is critical in vacuum and gas applications.

Related Resources

Chemical Compatibility

Check butyl resistance to specific chemicals and media.

Sheet Rubber Selection

Compare IIR against other rubber compounds side by side.

Shore Hardness Guide

Understand durometer scales and what hardness means in practice.

Related Materials

EPDM Neoprene (CR)

Need Butyl Rubber?

We supply butyl rubber in sheet, roll, and custom die-cut forms. Contact our team for pricing, data sheets, or technical assistance.

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Disclaimer

This resource is provided for general engineering reference only and does not constitute professional advice, specification, or guarantee of performance. Actual results depend on specific application conditions. Universal Gaskets Pty Ltd accepts no responsibility or liability for decisions made based on this information. For full terms, see our Terms & Conditions.