Butyl rubber (also known as Isobutylene Isoprene Rubber or IIR) is a synthetic rubber made by copolymerizing isobutylene with a small amount of isoprene. It is known for its excellent air impermeability, chemical resistance, and low permeability to gases, making it highly useful in specific industrial applications.

Key Properties of Butyl Rubber

• Low Air Permeability – One of the best materials for sealing air, making it ideal for inner tubes, tires, and vibration-damping applications.

• Excellent Chemical Resistance – Resistant to acids, alkalies, and polar solvents (though not resistant to hydrocarbons).

• Good Weather Resistance – Excellent resistance to ozone, UV radiation, and oxidation, which makes it useful for outdoor applications.

• Good Electrical Insulation – Acts as a good insulator, making it suitable for electrical applications.

• Low Temperature Flexibility – Retains its flexibility and elasticity at lower temperatures, performing well in cold environments.

• Good Impact Resistance – Provides toughness, making it durable under physical stress.

Limitations of Butyl Rubber

• Poor Oil and Fuel Resistance – Butyl rubber does not perform well when exposed to oils, fuels, or aromatic hydrocarbons.

• Lower Mechanical Strength – Not as strong or abrasion-resistant as some other rubbers like nitrile rubber or natural rubber.

• Limited High-Temperature Performance – While it has good low-temperature properties, it is not suitable for extremely high-temperature environments.

Common Applications of Butyl Rubber

• Tires – Used in inner liners of tires because of its ability to retain air pressure.

• Seals and Gaskets – Often used for applications requiring air or gas sealing properties, such as chemical tanks and piping systems.

• Medical Devices – Used in pharmaceutical stoppers and blood bags due to its inertness and biocompatibility.

• Vibration Dampers – Used in applications where reducing noise or vibration is important, such as in automotive engine mounts.

• Electrical Insulation – Applied in electrical cables and coatings to insulate and protect wires.

Butyl rubber's outstanding air retention properties and durability in extreme environmental conditions make it a popular choice in automotive, medical, and industrial applications.