Butyl rubber is a synthetic rubber, a copolymer of 98% isobutylene with 2% isoprene. The abbreviation IIR stands for isobutylene isoprene rubber.
Butyl rubber has excellent impermeability, and the long polyisobutylene segments of its polymer chains give it good flexibility. Isobutylene was discovered by Michael Faraday in 1825.
Butyl’s temperature range;- -40 to 110C Ignition Temp around 250C
Burning Characteristics;- Continuous burning with sweet smell and black fumes. A powder residue is left after burning.
Butyl rubber is impermeable to air and used in many applications requiring an airtight rubber.
It has excellent water, steam, ozone, and alkali resistance. It has very poor oil and fuel resistance.
Polyisobutylene and butyl rubber are used in the manufacture of adhesives, agricultural chemicals, fibre optic compounds, ball bladders, caulks and sealants, cling film, electrical fluids, lubricants (2 stroke engine oil), paper and pulp, personal care products, pigment concentrates, for rubber and polymer modification, for protecting and sealing certain equipment for use in areas where chemical weapons are present, as a petrol/diesel fuel additive, and chewing gum. The first major application of butyl rubber was tyre inner tubes. This remains an important segment of its market even today.
Very little Butyl sheeting is used these days for gaskets as generally it has been replaced by EPDM rubber.