Butyl elastomer

Polymerization. Polymerization reactions, which are addition reactions, are used to produce the principal products formed direcdy from butlylenes butyl elastomers polybutylenes and polyisobutylene (see Elastomers, synthetic Olefin polymers). 

Metal salts of neodecanoic acid have also been used as catalysts in the preparation of polymers. For example, bismuth, calcium, barium, and 2kconium neodecanoates have been used as catalysts in the formation of polyurethane elastomers (91,92). Magnesium neodecanoate [57453-97-1] is one component of a catalyst system for the preparation of polyolefins (93) vanadium, cobalt, copper, or kon neodecanoates have been used as curing catalysts for conjugated-diene butyl elastomers (94). 

S. Newman, "Use of Butyl Elastomers ia the Medical Industry," presented at MCA Rjcbber Division Meeting, Las Vegas, Nev., May 29, 1990. 

The next criterion was the selection of materials that would yield the desired mechanical properties. Butyl elastomer (HR), a copolymer of isobutylene with a small amount of isoprene, has outstanding low-temperature properties and very high damping, but has very high creep without cross-linking." It was theorized that a blend of SIBS TPE and butyl elastomer, filled to achieve the required minimum density of 2.4 g cm, would be a promising composite for less-lethal ammu-... 

Exxon Chemical Brochure on Conjugated Butyl Elastomer. 

Butyl diphenyl phosphate, 11 494 Butyl elastomers, 4 409 Butylene(s), 4 402-433 10 486 alkylation, 2 175-176 analysis, 4 421-422 chemical reactions, 4 404-410 economic aspects, 4 421 equilibrium distribution of ideal gas at selected temperatures, 4 409t feedstock for higher aliphatic alcohols, 2 211... 

EXXON chemical brochure on conjugated diene butyl elastomer. 

Exxon, chemical brochure on Conjugated Diene Butyl Elastomer. 

PE/Butyl Elastomer Blends The usefulness of crosslinked PE is well known [Charlesby, 1960 Chapiro, 1962 Dole, 1972,1973 Silverman, 1992], Unfortunately, crosslinked PE... 

Butyl rubber exhibits unusually low permeabihty to gases and outstanding resistance to attack by oxygen and ozone. It has excellent chemical inertness, due to the very low residual unsaturation, and good electrical properties because of its nonpolar saturated nature. Butyl rubber has good tear resistance. Butyl elastomers can be tailored to have good thermal stability and vibrational damping eharacteristics. 

Cellulose butyrate (also carbon black reinforcing pigment) Chlorinated butadiene rubber Conjugated diene butyl elastomer Cellulose plastics in general... 

The most important physical properties of butyl rubber are essentially the same as those of poly-isobutylene low permeabihty, good chemical and thermal stabihty due to the low imsaturation couteut, aud high damping. Butyl elastomers... 

Halogenation of the isoprene enchainments in butyl elastomers yields halobutyl elastomers. Reaction of the isoprene units with elementary bromine or chlorine leads to the formation of allylic halide units along the chain—a substitution as opposed to addition across the double bonds. This leads to much faster curing, which permitted the development of tubeless tires, as adhesion of halobutyl to the rest of the tire could be achieved. Halobutyls are primarily used by the tire industry to form the inner liner of the tubeless tire. Other applications are similar to that of butyl. Chlorobutyl is also used in pharmaceutical stoppers. 

Fig. 32 Kinetic characteristics for thermal oxidation of some rubbers assessed at three temperatures. The data were taken from [96J1]. (white) butyl elastomer, (dark grey) chlorobutyl elastomers, (pale grey) bromobutyl elastomer, (a) induction time of oxidation, (b) oxidation rate, (c) maximum oxidation time.

Halogenated Butyl. Butyl elastomers have a low density of unsaturation, which results in a low cure rate when conventional vulcanization systems are used. Butyl copolymers containing a small amount of combined chlorine or bromine are vulcanized more quickly than normal butyl rubber because the halogen atoms provide additional sites for the cross-linking process. Butyl rubber has poor adhesive properties to metals and other rubbers because of the lack of polar groups. This is the reason for using halogenation. 

Poly isobutylene, PIB, is a homopolymer of high molecular weight. The butyl elastomers are copolymers of isobutylene with sufficient isoprene (0.5-2.5%) to permit crosslinking. Most butyl compositions are one-component, e.g., tapes or liquid gun-grade caulks. They may be modified with plasticizers such as polybutene, or tackifiers and fillers such as calcium carbonate and fibrous talc. Two-component, curing butyl sealants are also available. 

These are superior to oleoresinous caulks in weather resistance, ozone resistance, and impermeability to gases and vapors. Although not truly elastomeric, they can be used safely in joints with movement of up to 10-15%. They are solvent solutions of uncured butyl elastomers with 17-20% polymer and solids content... 

High performance elastomeric butyl tapes are available for large window lite glazing in high-rise structures and for windshield sealing. These usually contain crosslinked butyl elastomers (20-40%) plus poly butenes, resinous tackifiers, and reinforcing fillers such as carbon black and platy talc. Chlorobutyl rubber compositions are available for faster and more thorough vulcanization. 

Exxon Mobil in brochures argues that butyl elastomer (HR) apparently is miscible with chlorobutyl elastomer (CIIR) and bromobutyl elastomer (BUR). This occurs because they have the same backbone structure of polyisobutylene and polyisoprene with an occasional different functional group of chlorine and bromine, respectively [33,34]. 

Many workers have measured microwave properties of blends of CPs with thermoplastics or with materials such as teflon. Fig. 12-6 shows e and e for P(Py)/teflon blends measured at 2 GHz by Lafosse [342]. It is seen that the rise in permittivity closely approximates the percolation threshold for DC conductivity, and that for the more conductive blends (P(Py)> ca. 0.15) the Loss Tangent is of the order of 10, indicating good absorption. Hourquebie et al. [483] studied P(Py) blends with a butyl elastomer, an epoxy, and teflon emulsion, and showed that a plot of log(e") vs. log(frequency) was linear over the 130 MHz to 18 GHz range their data however showed attenuation to be poor or moderate. In a study of P(Py) "latexes", Henry et al. [484] obtained typical values of e and e" at 5 GHz of ca. 945 and 1086. In a study of P(Py) blends with PVC, Jousse et al. [340] observed that for a pressed blend, classical microwave behavior, i.e. a monotonic fall of permittivities with frequency (Fig. 12-7a) is observed, whilst for injection-molded blends (Fig. 12-7b)... 

When this process first was introduced, the TBA was of low value, so the TBA/PO ratio was kept to a minimum. Since that time, valuable uses have been found for the TBA. t-Butanol is used as an octane enhancer in gasoline, competing with methanol, ethanol, and MTBE. Dehydration of TBA yields high-purity isobutylene, which is converted primarily into MTBE, butyl elastomers, polyisobutylenes, and a variety of substituted phenols and cresols, mercaptans, and amines. More than 450 million lb of isobutylene is produced from TBA. 

Research has shown that the bondability of elastomers is a function of polarity. The less polar EPDM and butyl elastomers, the more difficult they are to bond than are the more polar nitrile, neoprene, styrene-butadiene rubber (SBR), and NR. 

BOPP Biaxially oriented poly(propylene) film CDB Conjugated diene butyl elastomer... 

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