Isobutylene, physical properties

Kennedy J.P. and Price J.L., S3Tithesis, characterization and physical properties of poly(methyl methacrylate-b-isobutylene-b-methyl methacrylate) triblock copol3miers, Polym. Mater. Set Eng., 64, 40, 1991. 

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

Methylpropanal, physical properties of, 2 60t 4 459t 2-Methylpropane, 78 594 2-Methylpropanoic (isobutyric) aid, physical properties, 5 35t Methylpropanol, 7 257t 2-Methylpropene, 4 402 78 594. See also Isobutylene... 

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. ... 

R.F. Storey, B.J. Chisholm, and M.A. Masse, Morphology and physical properties of poly(styrene-b-isobutylene-b-styrene) block copolymers, Polymer, 37(14) 2925-2938, July 1996. 

Commercial products based on copolymers of ethylene and TEE are made by free radical-initiated addition copolymerization.69 Small amounts (1 to 10 mol%) of modifying comonomers are added to eliminate a rapid embrittlement of the product at exposure to elevated temperatures. Examples of the modifying comonomers are perfluorobutyl ethylene, hexafluoropropylene, perfluorovinyl ether, and hexafluoro-isobutylene.70 ETFE copolymers are basically alternating copolymers,70 and in the molecular formula, they are isomeric with polyvinylidene fluoride (PVDF) with a head-to-head, tail-to-tail structure. However, in many important physical properties, the modified ETFE copolymers are superior to PVDF with the exception of the latter s remarkable piezoelectric and pyroelectric characteristics. 

This contradiction between the American and Fitmish workers have not yet been resolved. In this paper it will be shown that Sivola and Harva 17) are in error, that they have committed an experimental error which led to incorrect conclusions and that isobutylene and 0-pinene can readily be copolymerized to high molecular wei t product of interesting physical properties. 

Table 1. Synthesis, characterization and physical properties of poly(isobutylene-co-/3-pinene)... 

As discussed in the introducticm to the fint p r of this series, erne of the objectives of this study was the synthesis of a series of novel hi molecular wei t cc edymen of isobutylene and pinene having useful physical prcf>erties. The physical properties of these copolymers were to reflect soff isobutylene and hard 0 wene structural units. 

Some physical properties of random poly(isobutylene-co-P-pinene) have been inves-tipted. These copolymers are rubbery, leathery or glassy materials depending on the relative amount of isobutylene and 0 pinene units in the chain. 7 g s determined by differential scanning calorimetry range from —65° for copolymers containing... 

Relationships between microvoid heterogeneity and physical properties in crosslinked elastomers, poly-(isobutylene-/7-methylstyrene-p-bromomethylstyrene) (PIB-PMS/BrPMS) terpolymers, were identified by a 3D-NMR imaging study. Three-dimensional reconstruction of the sample images reveals that the voids are spherically shaped. The experimental results indicate that high microvoid density in cured elastomers leads to crack initiation and accelerated crack growth, thereby resulting in premature mechanism failure of the materials. 

As the foregoing discussion has already indicated, we have partially reached our goals. We have prepared high molecular weight isobutylene-rich poly(isobutylene-co-0-pinenes), however, we could not synthesize the high molecular weight 0-pinene-rich copolymer. Indeed, the physical properties of 0-pinene-rich copolymers were so poor (brittleness on account of low molecular weights) that property characterization studies have not been carried out. 

The results of a series of runs carried out to obtain amounts of copolymers sufficient for physical property characterization are summarized in Table 1 of the first paper of this series. It is evident that depending on the relative amount of isobutylene and 3-pinene units in the copolymer, poly(is6butylene-co/3-pinene)s are rubbery, leathery, or glassy materials. 

Vapor-Kquid equilibrium data of poly(isobutylene) in n-pentane and n-heptadecane Data extract from Landolt-Bornstein VIII/6D3 Polymers, Polymer Solutions, Physical Properties and their Relations I (Thermodynamic Properties Equilibria of Ternary Polymer Solutions) ... 

Acrylic acid and methacryiic acid are selective oxidation products of propylene and isobutylene, respectively. The minor difference in structure between the two acids, the a-methyl substituent of methacryiic acid, results in minimal physical property differences as indicated in Table 1. However, this structural difference distinctly affects polymerization and copolymerization kinetics and the characteristics of the resulting polymers. 

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... 

In the hquid phase, the molecules are firee to tumble in space, but they do tend to move in such a way so as to attract each other more often then they repel each other. The resulting net attraction between the molecules results in an elevated melting point and boiling point. To iUusttate this, compare the physical properties of isobutylene and acetone ... 

In addition to the characteristics of the substrates and the final reaction products, it would be very interesting to try to predict the catalytic activity of a catalyst from its physical properties. It is well known that for pure metal oxides a correlation exists between catal5lic activity and the heat of formation of the metal oxide. Moro-Oka and CO-workers demonstrated for several substrates (propylene, isobutylene, acetylene, ethylene and propane) that the lower the heat of formation of the catalyst oxide, divided by the number of oxygen atoms in the oxide, then the greater the activity for total oxidation. From the metal oxides tested, those of palladium and platinum were the most active, which corresponds to the elements with the most unstable oxides. ... 

Drug-eluting coronary artery stents are currently coated with a styrene-fc-isobutylene- -styrene copolymer, which is mixed with a drug that inhibits cell growth. This coating has good physical properties and does not degrade in the body. 

Mechanical Behavior. The ionomers, - poly[Isobutylene-co-(4-methyl styrenyl, triphenyl phosphonium bromide or tetraphenyl borate)] were found to be different in physical appearance(hard and strong) and tougher than the starting material, the Exxpro elastomer. The mechanical properties of these quaternary phosphonium... 

The physical, chemical, and compounding properties of the isobutylene family of polymers will vary with molecular weight, amount of unsaturation, the minor constituents in the polymer and, in certain instances, chemical modification. With proper allowance for gross differences in molecular weights, butyl and polyisobutylene can often be used interchangeably in cement and adhesive compositions that will not be cured. 

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