ISOBUTYLENE POLYMER

Butyl rubber and other isobutylene polymers of technological importance iaclude various homopolymers and isobutylene copolymers containing unsaturation achieved by copolymerization with isoprene. Bromination or chlorination of the unsaturated site is practiced commercially, and other modifications are beiag iavestigated. 

The relationship between intrinsic viscosity [Tj] and mol wt for isobutylene polymers in diisobutylene is (79) ... 

Blends of isobutylene polymers with thermoplastic resins are used for toughening these compounds. High density polyethylene and isotactic polypropylene are often modified with 5 to 30 wt % polyisobutylene. At higher elastomer concentration the blends of butyl-type polymers with polyolefins become more mbbery in nature, and these compositions are used as thermoplastic elastomers (98). In some cases, a halobutyl phase is cross-linked as it is dispersed in the polyolefin to produce a highly elastic compound that is processible in thermoplastic mol ding equipment (99) (see Elastomers, synthetic-thermoplastic). ... 

It is not possible to polymerise vinyl ethers by free-radical-initiated methods but, as with isobutylene polymers, it is possible to make polymers using Friedel-Crafts type catalysts. 

Example 2. Vinviidene Chloride Isobutylene Copolymer. The next example is for the carbon-13 spectrum of copolymer vinylidene chloride isobutylene. Figure 5 shows the full spectrum and the peak assignment listing for the non-protonated vinylidene chloride carbon in the 84-92 ppm range. Triad assignments were made (Crowther, M. W., 1987, Syracuse University, unpublished data) using the two-dimensional COLOC (20) experiment. There are ten v-centered pentads representing different environments for the vinylidene chloride carbon. The i represents the non-protonated carbon in the isobutylene polymer unit. 

Isooiefin Polymers of molecular wt 50000 to 100000, such as Isobutylene polymer, were patented as thickeners for flammable naphtha used in incendiary bomb mixts. Up to 25% may be incorporated. Small amts of metal soaps may replace part of the polymer. Thermite mixts, Na, K and P may also be included in such an incendiary filler Ref H.H. Cooke, E. J. Holzclaw, USP s 2445311 2445312 (1948) CA 42, 7985 (1948)... 

Sulfuric acid (3) has been used in the past as a polymerization catalyst both in the Cold Sulfuric Acid Process and the Hot-Acid Polymerization Process. Its main utility today lies in its use for selectively absorbing isobutylene from mixed butane-butylene streams for use in the production of synthetic rubber. The products are a di-isobutylene polymer and a butane-normal butylene mixture. The di-isobutylene is also used to a small extent by the chemical industry. 

Isoolefin Polymers of molecular wt 50000 to 100000, such as Isobutylene polymer, were patented as thickeners for flammable naphtha... 

Isobutylene polymers and copolymers can be prepared by polymerization in the presence of vanadium tetrachloride or titanium tetrachloride and sodium amalgam [136]. 

Transition metal catalyzed, ring opening polymerization Dispersion, cationic polymerization Homogeneous/precipitation, cationic polymerization Homogeneous, free radical/cationic polymerization Precipitation, free radical polymerization Dispersion, free radical polymerization Norbornene polymer, polycarbonate Isobutylene polymer Vinyl ether polymer Amorphous fluoropolymers Vinyl polymer, semicrystalline fluoropolymers Polyvinyl acetate and ethylene vinyl acetate copol5Tner... 

It is concluded that, for the most part, catalysis in the porous crystalline zeolites occurs within the intracrystalline voids. However, some role must be allocated to the external surface, especially at higher temperatures, to explain the formation of isobutylene polymers over chabazite 19), the dehydrohalogenation of ter<-butyl chloride over 5A 20), and the detection of small amounts of triphenylbenzene and triphenylphenanthrene in the condensation of acetophenone over hydrogen Y (HY) zeolite 21). Table I shows the external surface areas of... 

The liquid scrubbed hydrogen sulfide is mixed with the olefinic inaterial (usually a 165-200°C fraction of propylene-isobutylene polymer) in a molar ratio of 1.5 1 and passed into a catalyst chamber in the liquid phase. The residence time in the catalyst case is 1 hr with the temperature under 150 C. The conversion is about 35 per cent or better with a very active catalyst, and yields vary from 60-80 per cent based on olefin charged. The product is purified by vacuum fractionation after the recycle hydrogen sulfide is stripped at about 50 lb pressure. The (d fin is taken overhead in one column and the mercaptan in a second. The final material contains 90 plus per cent isomeric mercaptans. 

Tire-Tread Formulations. The isobutylene polymers are notorious for their poor affinity toward carbon black relative to other elastomers that are rich in unsaturation. Yet reinforcement with carbon black is critical to use in these polymers in tire treads where a certain degree of abrasion resistance is required. It is expected that the Exxpro-phosphonium ionomers can interact with the carbon black(both regular and oxidized forms) surface and thereby localize them within the PIB phase as shown ... 

Displayed in Fig. 14.1 are the predicted interactional free energies for mixtures of polyacrylonitrile latex particles, of 100 nm radius, stabilized by polystyrene (polymer 2) and pol> isobutylene (polymer 3), assuming a constant segment density for both polymers (Feigin and Napper, 1978). Figure 14. la shows the... 

Faust, R., Kennedy, J.P., 1986. Living carbocationic polymerization 3. Demonstration of the living polymerization of isobutylene. Polym. Bull. 15 (4), 317-323. 

Isobutylene/maleic anhydride copolymer. See Isobutylene/MA copolymer Isobutylene polymer Isobutylene resin. See Polyisobutene... 

Synonyms Isobutene homopolymer Isobutene polymer Isobutylene homopolymer Isobutylene polymer Isobutylene resin 2-Methyl-1-propene, homopolymer 2-Methylpropene polymer PIB Polyisobutylene Polymerized 2-methylpropene... 

J.A. Sangalov and K.S. Minsker in Isobutylene Polymers and Copolymers Fundamental Problems and Application Aspects, Gilem, Ufa, Russia, 2001. [In Russian]... 

Apart from wetting agents, the original formulation (either powder or suspension) may contain additives to improve the adhesion by virtue of their tackiness. Such additives are called sticking agents. For example, DDT formulations may contain stearic acid, calcium stearate, paraffin wax, or other such components. Various oils as well as elastomeric copolymers of natural or synthetic materials—particularly butylene or isobutylene polymers with molecular weights of 200,000 to 300,000—can be used for this purpose also used are the Li, Zn, Ca, Al, and Cd salts of fatty acids. 

Pemecker, T. and Kennedy, J. P. (1994) Carbocationic polymerizations in supercritical carbon dioxide I. Exploratory experiments with isobutylene, Polymer Bulletin, 32, 537-5433. 

Isobutylene has been of interest since the early days of synthetic polymer research when Friedel Crafts catalysts were used to prepare elastic materials. Isobutylene polymers of commercial importance include homopolymers and copolymers containing small amounts of isoprene or p-methylstyrene. Currently, chlorinated and brominated derivatives of butyl(poly[isobutylene-co-isoprene]) have the highest sales volume. 

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