Tubeless tires

Butyl and Halobutyl Rubber. Butyl mbber is made by the polymerization of isobutylene a small amount of isoprene is added to provide sites for curing. It is designated HR because of these monomers. Halogenation of butyl mbber with bromine or chlorine increases the reaction rate for vulcanization and laminates or blends of halobutyl are feasible for production of mbber goods. It is estimated that of the - 100 million kg of butyl (UR) and halobutyl (HIIR) mbber in North America, over 90% is used in tire apphcations. The halogenated polymer is used in the innerliner of tubeless tires. Butyl mbber is used to make innertubes and curing bladders. The two major suppHers of butyl and halobutyl polymers in North America are Exxon and Bayer (see ELASTOLffiRS,SYNTHETIC-BUTYLrubber). 

Butyl ruhher vulcanizates have tensile strengths up to 2,000 psi, and are characterized hy low permeahility to air and a high resistance to many chemicals and to oxidation. These properties make it a suitable rubber for the production of tire inner tubes and inner liners of tubeless tires. The major use of butyl rubber is for inner tubes. Other uses include wire and cable insulation, steam hoses, mechanical goods, and adhesives. Chlorinated butyl is a low molecular weight polymer used as an adhesive and a sealant. 

First tubeless tire (Litchfield of Goodyear Tire Co.)... 

Butyl rubber is made by polymerizing isobutylene with a small quantity of isoprene. Its main uses are in the making of truck tire inner tubes, inner coatings for tubeless tires, and automobile motor mounts. 

Halogenation of the isoprenyl unit provides enhanced cure reactivity to the rubber molecule, increases the covulcanizability and adhesion to unsaturated tire elastomers, and opens the field of tubeless tire innerliners. 

Halobutyls, which can easily covulcanize with high-unsaturation rubbers, are used in innerliners for tubeless tires as component for sidewalls of passenger-car tires and for heat-resistant truck inner tubes. Other applications involve a variety of sealant tapes, caulks, and pharmaceutical closures. 

Inner liner formulated to ensure retention of compressed air in tubeless tire, good air retention, moisture impermeabihty, flex fatigue resistance, durability... 

Lubricating oils, sealants copolymerized with 0. -2.S mol% isoorene to produce Butyl rubber for tire inner tubes and inner iiners of tubeless tires. 

Barrier Materials. Polymers are often used as barriers to keep small molecules in or to keep them out. One common example is rubber tubes for tires or more recently the inner liner of tubeless tires. The purpose of such a material is to contain air under pressure to maintain tire inflation. From the data in Table I, it is clear that butyl rubber is a much better material for this purpose than natural rubber. Because of this, butyl rubber has entirely displaced natural rubber from this market. Aside from its prohibitive price, silicone rubber would be totally unsatisfactory for this use because of its high gas permeability. 

Before the introduction of tubeless tires butyl rubber was used for inner tubes because it is impervious to air. Subsequently halogenated butyl rubbers were developed (halobutyls), which could be cured at higher temperature and vulcanized with other rubbers. Both chlorobutyls and bro-mobutyls are manufactured. These types of rubber are used in tubeless tires bonded to... 

As a result of its very low gas permeability, butyl rubber is used predominantly in the inner tubes of tires and inner liners for tubeless tires. Some of the other uses of butyl rubber include sealants, adhesives, hoses, gaskets, pads for truck cabs, bridge bearing mounts, and other places where vibration damping is important. 

Permeability of gases and vapors through a film is an important consideration in many applications of polymers. A high permeability is sometimes desirable. For example, in fruit-packaging applications of plastics film it is desirable to have high permeability of carbon dioxide. On the other hand, for making inner tube and tubeless tires, or in a child s balloon, the polymer used must have low air permeability. 

Tubeless tires have, instead of an inner tube, an inner liner, which is a layer of rubber cured inside the casing to contain the air, and a chafer around the bead contoured to form an airtight seal with the RIM. 

A heavy-duty tmck tire would typically have the size designation of 11R24.5 for a conventional tubeless tire a low-profile metric tire typically could be sized 295/75R22.5. For the conventional tire,... 

Uses of Butyl Ruhher. Butyl rubber is used in the manufacture of inner liners of tubeless tires, inner tubes, cable insulation, pharmaceutical stoppers, curing bags, and bladders for tire manufacture. When tires are in the molds for vulcanization, the inside of the tire is filled with a butyl rubber bag or bladder of steam under enough pressure to obtain the vulcanization temperature. This is possible only because of the good resistance of butyl rubber to heat and water. 

Uses of Chlorobntyl and Bromobntyl Rubbers. CIIR and BUR are used in inner liners of tubeless tires with improved (over HR) covulcanization (in blends) and adhesion to other components of the tires, in inner tubes for heavy-duty applications such as in truck and bus tires, and in belts, hoses, seals, injection molded parts, and pharmaceutical stoppers. 

Butyl rubber n (1940). A synthetic elastomer produced by copolymerizing isobutylene with a small amount (ca 2%) of isoprene or butadiene. It has good resistance to hear, oxygen and ozone, and low gas permeability. Thus, it is widely used in inner tubes and to line tubeless tires. Butyl rubber is a vinyl polymer, and is very similar to polyethylene and polypropylene in structure, except that every other carbon is substituted with two methyl groups. It is made from the monomer isobutylene, by cationic vinyl polymerization. It can also go by the name of polyisobutylene. (1) Generic name for vulcanizable elastic copolymers of isobutylene and small amounts of diolefins. (2) Mixture of isobutylene, 98% and... 

Other Devices and Materiak. Anything that can be applied to the leak to stop or slow down the release without making things worse would be considered acceptable as patching /plugging material. Tubeless tire patches, chemical-resistant tapes, lead wool, quick-setting urethane foam, plumber s plugs, foam insulation material, and a whole host of other materials and devices may be considered. 

Tubeless tire B.F. Goodrich announces development of the tubeless tire. 

Halogenated butyl rubber greatly extended the usefulness of butyl rubber by providing much higher vulcanization rates and improving the compatibility with highly unsaturated elastomers, such as natural rubber and styrene-butadiene rubber (SBR). These properties permitted the production of tubeless tires with chlorinated or brominated butyl innerliners. The retention of air pressure (5) and low intercarcass pressure (6) extended tire durability. 

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. 

Isobutjdene CH3 CH2=C CH3 Polyisobutylene (PIB) CH3 / 1 V (-CH9—C )- 2 1 CH3 Lubricating oils, sealants, copolymerized with 0.5-2.5 mol% isoprene to produce Butyl rubber for tire iimer tubes and inner liners of tubeless tires. 

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