Radial tires, elastomers used

The principles of compounding were reviewed earlier in this text and cover the fundamental characteristics of polymers, filler systems, and the basics of vulcanization in the context of compound development for tire applications. A compound formulation consists of four basic components the polymer network, the filler or particulate reinforcing system, the stabilizer system, and the vulcanization system (Figure 14.21). In addition a series of secondary materials such as resins, processing oils, and short fiber reinforcements may be included in a formula (Duddey, 2004 Rodgers and Waddell, 2004 Long, 1985). Elastomers used in radial tires are basically of four types ... 

Elastomers used in radial tires are basically of four types ... 

Uses. BR was first used largely in the blend of elastomers in tire treads to give improved abrasion resistance. Because of the emergence of radial tires, BR is largely used in tire carcasses, sidewalls and bead compounds. BR is important in winter tire treads because it gives improved ice traction that it confers. Over 90 percent of the BR production is used in tires. 

About 70% of natural rubber consumption goes into tire production while the remaining 30% is used by the nontire sector. There is some substitutability of various synthetic elastomers for natural rubber, but it is rather limited. This substitutability is restricted for the tire sector, which globally uses almost half of its total rubber requirement as natural rubber. In the short term, it is technically very difHcult to make major substitutions of synthetic rubber for NR use. Some applications are very critical, such as the use of NR in wire adhesion compounds for the production of steel-belted radial tires. Also, the use of natural rubber is very critical in the production of very large off-the-road tires. However, the natural rubber requirements of the nontire sector were only 29% of its total rubber usage in the year 2000. The nontire sector only used about 22% of its total rubber requirement as natural rubber in 2010. Many times it is easier in the nontire sector to substitute specialty syn-... 

SBR is the largest volume synthetic elastomer used by the rubber industry. Also, SBR is usually the least expensive elastomer, which may explain its very wide use, especially in the tire sector. SBR usually represents about 25% of the total monetary value of all synthetic elastomers. By tonnage, SBR now represents over one-third of synthetic rubber production however, before the introduction of radial tires in the 1960s, SBR represented 55%. Not only is SBR used in tire production, it is also used in the manufacture of conveyor belts, industrial hose, and footwear, to name a few uses. About 76% of SBR is used in tires, 15% in mechanical rubber goods, 5% in nontire automotive, and about 4% in miscellaneous applications such as shoe soles, floor tiles, and adhesives. 

The reaction of a bifunctional organosilane with precipitated silica involves the hydrophobation of the alkoxy group of the silane with a surface silanol group of the silica, followed by reaction of the sulfur-containing function of the silane with an olefin group of the elastomer to afford a covalently bonded structure. This silane-coupled silica is useful in improving the abrasion resistance of silicas to levels of carbon blacks, and promoted their use in the treads of radial passenger tires. 

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