ISOBUTYLENE ISOPRENE

NR, natural mbber CR, chloroprene SRs, synthetic mbbers IR, natural isoprene SBR, styrene—butadiene mbber BR, butadiene EPDM, ethylene—propjiene-diene EPM, ethylene—propylene polymer HR, isobutylene—isoprene NBR, nitrile—butadiene. 

RRA cure test recipe for HR reclaim, cured 30 min at 160°C. HR is isobutylene—isoprene mbber (butyl mbber). 

Natural mbber comes generally from southeast Asia. Synthetic mbbers are produced from monomers obtained from the cracking and refining of petroleum (qv). The most common monomers are styrene, butadiene, isobutylene, isoprene, ethylene, propylene, and acrylonitrile. There are numerous others for specialty elastomers which include acryUcs, chlorosulfonated polyethylene, chlorinated polyethylene, epichlorohydrin, ethylene—acryUc, ethylene octene mbber, ethylene—propylene mbber, fluoroelastomers, polynorbomene, polysulftdes, siUcone, thermoplastic elastomers, urethanes, and ethylene—vinyl acetate. 

Butyl Rubber isobutylene—isoprene good good ... 

A living cationic polymeriza tion of isobutylene and copolymeriza tion of isobutylene and isoprene has been demonstrated (22,23). Living copolymerizations, which proceed in the absence of chain transfer and termination reactions, yield the random copolymer with narrow mol wt distribution and well-defined stmcture, and possibly at a higher polymerization temperature than the current commercial process. The isobutylene—isoprene copolymers are prepared by using cumyl acetate BCl complex in CH Cl or CH2CI2 at —30 C. The copolymer contains 1 8 mol % trans 1,4-isoprene... 

A partially cross-linked, isobutylene—isoprene—divinylbenzene terpolymer containing some unreacted substituted vinylbenzene appendages is commercially available from Polysar Division, Bayer AG. Because of the residual reactive functionality, it can be cross-linked by peroxides that degrade conventional butyl mbbets. It is employed primarily in the manufacture of sealant tapes and caulking compounds (31). 

Polyisobutylene and isobutylene—isoprene copolymers are considered to have no chronic hazard associated with exposure under normal industrial use. Some grades can be used in chewing-gum base, and are regulated by the PDA in 21 CPR 172.615. Vulcanized products prepared from butyl mbber or halogenated butyl mbber contain small amounts of toxic materials as a result of the particular vulcanization chemistry. Although many vulcanizates are inert, eg, zinc oxide cured chlorobutyl is used extensively in pharmaceutical stoppers, specific recommendations should be sought from suppHers. 

Until the mid-1950s the only polyolefins (polyalkenes) of commercial importance were polyethylene, polyisobutylene and isobutylene-isoprene copolymers (butyl rubber). Attempts to produce polymers from other olefins had, at best, resulted only in the preparation of low molecular weight material of no apparent commercial value. 

Compound A—A blend of cured and uncured isobutylene-isoprene copolymer... 

Table IV shows the data on rigidity changes of the end-sealing compounds at two dose levels. Rigidity was determined by torsional braid analysis (5). These data indicate that the blend of cured and uncured isobutylene-isoprene copolymer was softened most by the irradiation treatment, the blend of polychloroprene and butadiene-styrene copolymer softened the least, and the blend of polychloroprene and the uncured isobutylene-isoprene copolymer was intermediate. Increasing the irradiation dose from 3-4 Mrad to 6-7.5 Mrad decreased the rigidity of the three end-sealing compounds. The irradiation temperature did not significantly influence rigidity.

The production test showed that the epoxy phenolic enamel was the preferred enamel for coating tinplate containers used in packaging irradiation-sterilized ham and beef. The preferred end-sealing compound for the same application was the blend of cured and uncured isobutylene-isoprene copolymer. 

The evaluation of the components of the tinplate container showed that the preferred enamel for irradiation processing was the epoxy phenolic the preferred end-sealing compound was the blend of cured and uncured isobutylene—isoprene copolymer. Component testing of tinplate and solder for possible changes in mechanical properties, microstructure, and corrosion resistance indicated that the radiation caused... 

Abbreviation for isobutylene-isoprene rubbers, popularly known as butyl rubbers. 

Isobutylene-based (C-4) process, for methyl methacrylate production, 16 244,254r-257 Isobutylene—isoprene-divinylbenzene terpolymers, 4 437... 

Isobutylene isoprene rubber (IIR), in tire compounding, 21 807 Isobutyl formate, physical properties, 6 292t... 

Isobutylene-isoprene elastomer (butyl rubber Sparks and Thomas)... 

Several polymers based on 1,3-dienes are used as elastomers. These include styrene-1,3-butadiene (SBR), styrene-1,3-butadiene terpolymer with an unsaturated carboxylic acid (carboxylated SBR), acrylonitrile-1,3-butadiene (NBR or nitrile rubber) (Secs. 6-8a, 6-8e), isobutylene-isoprene (butyl rubber) (Sec. 5-2i-l), and block copolymers of isoprene or... 

For (a), hydroxypropyl cellulose (HPC) (6-8), poly(vinyl pyrrolidone) (PVP) (9,10), poly(acrylic acid) (PAA) (9), and poly(dimethyl siloxane) (PDMS) (11) are usually employed. Ober et al. reported that the copolymers of isobutylene/isoprene and various methacrylates, which have weak polarity, are appropriate stabilizers for... 

It is possible to cross-link polyisobutylene and poly(isobutylene-isoprene) and chlorobutyl rubber by means of certain additives however, the physical properties of the vulcanizates prepared by conventional curing methods cannot be attained. The most promising results were obtained with chlorobutyl compounds containing thioether polythiols as prorads. ... 

Hydroxpropyl Cellulose Hydroxypropyl Methylcellulose Isobutylene-Isoprene Copolymer Locust Bean Gum... 

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