- Butyl rubber is the copolymer of isobutylene and a small amount of isoprene.
- Also known as IIR. IIR stands for Isobutylene Isoprene Rubber.
Details and properties of butyl rubber:
- First it got commercialized in 1943.
- The primary attributes of butyl rubber are excellent impermeability/air retention and good flex properties, resulting from low levels of unsaturation between long polyisobutylene segments.
- Tyre innertubes were the first major use of butyl rubber.
- The development of halogenated butyl rubber (halobutyl) in the 1950’s and 1960’s greatly extended the usefulness of butyl by providing much higher curing rates and enabling covulcanization with general purpose rubbers such as natural rubber and styrene-butadiene rubber(SBR).
- These properties permitted development of more durable tubeless tires with the air retaining innerliner chemically bonded to the body of the tire. Tire innerliners are by far the largest application for halobutyl today. Both chlorinated (chlorobutyl) and brominated (bromobutyl) versions of halobutyl are commercially available.
- In addition to tire applications it also has good impermeability, weathering resistance, ozone resistance, vibration dampening, and stability make them good materials for pharmaceutical stoppers,construction sealants, hoses, and mechanical goods.
- Butyl rubber is difficult to handle during manufacturing because of its tendency to trap air, blister, and creep.
- Characteristics and flame resistance are poor. Butyl is not recommended for use with petroleum oils, fluids, or solvents.
- It has poor resistance to aromatic hydrocarbons , aliphatic hydrocarbons (e.g., kerosene, turpentine), coal, tar, and diester-based lubricants. Cold weather properties for butyl rubber are fair.
- As fuel and lubricant additive
Polyisobutylene (in the form of polyisobutylene succinimide, PIBSI) has interesting properties when used as an additive in lubricating oils and motor fuels. Polyisobutylene added in small amounts to the lubricating oils used in machining results in a significant reduction in the generation of oil mist and thus reduces the operator’s inhalation of oil mist. When added to crude oil it increases the oil’s viscoelasticity when pulled, causing the oil to resist breakup when it is vacuumed from the surface of the water.
Polyisobutylene is used in some formulations as a thickening agent.
- As explosives
Polyisobutylene is often used by the explosives industry as a binding agent in plastic explosives such as C-4. Polyisobutylene binder is used because it makes the explosive more insensitive to premature detonation as well as making it easier to handle and mold.
- In Sporting equipment
Butyl rubber is used for the bladders in sporting balls, e.g. Rugby balls, footballs, basketballs, netballs to provide a tough, airtight inner compartment.
- In Damp proofing and roof Repair
Butyl rubber sealant is used for damp proofing, rubber roof repair and for maintenance of roof membranes (especially around the edges). It is important to have the roof membrane fixed, as a lot of fixtures (i.e., air conditioner vents, plumbing and other pipes, etc.) can considerably loosen it..
Polyester fabric laminated to butyl rubber binder provides a single-sided waterproof tape that can be used on metal, PVC, and cement joints. It is used for repairing and waterproofing metal roofs.
- In Gas masks and chemical agent protection
Butyl rubber is one of the most robust elastomers when subjected to chemical warfare agents and decontamination materials. It is therefore used to create seals in gas masks and other protective clothing.
- In Medical Stoppers
Butyl and Bromobutyl rubber are commonly used for manufacturing rubber stoppers used for sealing medicine vials and bottles.
- In Chewing gum
Most modern chewing gum uses food-grade butyl rubber as the central gum base, which contributes not only the gum’s elasticity but an obstinate, sticky quality which has led some municipalities to propose taxation to cover costs of its removal.
- In Tyres
Butyl rubber and halogenated rubber are used for the inner liner that holds the air in the tyre.
SOME IMPORTANT QUESTIONS AND ANSWERS:
1) What is the other name of butyl rubber?
ans) The other name of butyl rubber is Isobutylene Isoprene Rubber.
2) Where is it used commonly?
ans) In tyres.
3)What is the limitation of butyl rubber?
ans) Butyl rubber is difficult to handle during manufacturing because of its tendency to trap air, blister, and creep.
4) Where was butyl rubber first used?
ans) In inner tube of tyres.
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