- Butyl rubber
Butyl rubber—also known as polyisobutylene and PIB (C4H8)n is a
synthetic rubber , ahomopolymer of 2-methyl-1-propene. Polyisobutylene is produced by polymerization of about 98% ofisobutylene with about 2% ofisoprene . Structurally, polyisobutylene resemblespolypropylene , having twomethyl group s substituted on every othercarbon atom. It has excellent impermeability, and the longpolyisobutylene segments of itspolymer chains give it good flex properties. Polyisobutylene is a colorless to light yellowviscoelastic material. It is generally odorless and tasteless, though it may exhibit a slight characteristic odor.The formula is:-(-CH2-C(CH3)2-)n-
It can be made from the
monomer isobutylene or CH2=C(CH3)2 viaradical polymerization ,cationic addition polymerization &anionic addition polymerization routes.A synthetic rubber, or
elastomer , polyisobutylene is impermeable to air and used in many applications requiring an airtight rubber. Polyisobutylene is used in makingadhesives , agricultural chemicals,fiber optic compounds,caulk s and sealants,cling film , electrical fluids, lubricants (2 cycle engine oil), paper and pulp, personal care products,pigment concentrates, for rubber and polymer modification, as agasoline /diesel fuel additive , and even inchewing gum . The first major application of butyl rubber wastire inner tube s. This remains an important segment of its market even today.Butyl rubber was first developed in 1937, by researchers
William J. Sparks andRobert M. Thomas , atStandard Oil 's (which becameExxon in 1972) Linden, N.J. laboratory. Texas Petrochemicals and Lubrizol Corporation are one of the largest manufacturers of PIB in North America.In 1950s and 1960s,
halogen ated butyl rubber (halobutyl) was developed, in its chlorinated (chlorobutyl) and brominated (bromobutyl) variant, providing significantly higher curing rates and allowing covulcanization with other rubbers likenatural rubber andstyrene-butadiene rubber. Halobutyl is today the most important material for inner tubes. The butyl rubber is vulcanized by elementalsulfur .Zinc oxide can be also used to vulcanize halobutyl.Uses
Fuel and lubricant additive
Polyisobutylene (in the form of polyisobutylene succinimide) has interesting properties when used as an additive in
lubricating oil s and motor fuels. Polyisobutylene added in small amounts to the lubricating oils used inmachining results in a significant reduction in the generation of oil mist and thus reduces the operator's inhalation of oil mist. [http://www.epa.gov/oppt/greenengineering/pubs/case_studies.html] It is also used to clean up waterborneoil spill s as part of the commercial product Elastol. When added tocrude oil it increases the oil'sviscoelasticity when pulled; causing the oil to resist breakup when it is vacuumed from the surface of the water.As a
fuel additive , polyisobutylene hasdetergent properties. When added todiesel fuel, it resists fouling offuel injector s, leading to reduced hydrocarbon andparticulate emissions . [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Retrieve&list_uids=7529704&dopt=Citation] [http://ehp.niehs.nih.gov/members/1994/Suppl-4/hammerle-full.html] They are blended with other detergents and additives to make a "detergent package" that is blended intogasoline and diesel fuel to resist buildup of deposits andengine knock . [http://www.cit.uscourts.gov/slip_op/Slip_op04/Slip%20Op%2004-87.pdf]Polyisobutylene is used in some formulations as a
thickening agent .Basketballs
Polyisobutylene is impermeable to air and it is normally used on the inside of basketballs to stop them from deflating.
Roof Repair
Butyl rubber sealant is used for 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.
Rubber roof is typically referred to a specific type of roofing materials that are made of Ethylene Propylene Diene Monomer (EPDM). The crucial component for the maintenance of the quality of such roofs is to avoid using harsh abrasive materials and petroleum-based solvents for their maintenance.
External Links
* [http://www.pslc.ws/mactest/pib.htm Brief overview of Polyisobutylene]
* [http://www.ffcr.or.jp/zaidan/FFCRHOME.nsf/7bd44c20b0dc562649256502001b65e9/916cae3da5a8a11b49256f320018877f/$FILE/D286.pdf Additional information]
* [http://www.txpetrochem.com/fw/main/Polyisobutylenes-32.html MSDS Sheets of Different polyisobutylene(PIB) grades depending upon molecular weights and chain lengths]
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