Butyl rubber is a synthetic rubber, a copolymer of isobutylene with isoprene. Butyl rubber is a good choice for shock absorption and has exceptionally low gas and moisture permeability and outstanding resistance to heat, aging, weather, ozone, chemical attack, flexing, abrasion, and tearing. It is resistant to phosphate ester based hydraulic fluids, and has excellent electrical insulation performance. Butyl is not recommended for use when in contact with petroleum oils and fluids.

Both o-rings and gaskets can be made from Buna materials.

Names: ButylIIRIsobutylene Isoprene Rubber

Compound Info

ASTM D1418 DesignationIIR
ASTM D2000/SAE J200 Type, ClassAA, BA, CA
Hardness (Shore A)40-90

Thermal Properties

Min Temp.-70°F (-56°C)
Max Temp.250°F (121°C)

Chemical Resistance

Esters, Alkyl Phosphate, Aryl Phosphate, Alcohols, Inorganic acids, aldehydes, Alkalies (both dilute & concentrated), Amines

NOT Compatible

LP gases & fuel oils, petroleum (both aromatic & non-aromatic)
Hydrocarbon fuels, Halogenated solvents
Mineral oil, silicone oil, and poor oil resistance

Disclaimer: These are general guidelines only. All materials should be tested in your application.