Radial tire sidewall

NR/EPDM-based sidewalls of radial tires are also prepared to get more durability and appearance. These blends with an EPDM content varying from 30 to 70 phr are used for making cables and conductors. 

There are certain technical limitations in the devulcanization of rubbers, and vulcanization is, in fact, not truly reversible (Pryweller, 1999). The partial devulcanization of scrap rubber will result in a degradation of physical properties. In many cases, this may limit the amount of substitution levels in high-tech applications such as passenger tires. But it can provide the compounder of less stringent products with an excellent low-cost rubber that can be used as the prime rubber or at very high substitution levels. According to Franta (1989), reclaim cannot be used for tread compounds in tires because every addition may decrease their resistance to wear. However, this statement has not been checked in case rubber devulcanized without an addition of chemicals. Considerable amounts of reclaim are consumed for carcasses of bias ply tires for cars if the compounds are of NR for carcasses of radial tires no reclaim is added. On the other hand, reclaim is added to compounds for bead wires and it may also be added to sidewalls. Within the framework of direct recycling options a number of applications for GRT outside the rubber industry have been proposed. Such applications include the use as a tiller in asphalt for the surface treatment of roads and as a rubberized surface for sport facilities. 

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. 

The next stage of our investigations was to study opportunities of application of new chlorine-containing cauotchouc CEPDC-2 in the formulas of rubbers for sidewall of radial tires and rubbers for production of diaphragm press. 

In this case we studied the opportunity of application of cauotchouc CEPDC-2 in rubber formula for sidewalls of radial tires, elastomeric part of which has diene cauotchoucs SIR-3 and CDR in ratio (50 50). The ratio... 

The rubber s polymer network allows elasticity and flexibility to be combined with crystallization-induced strength and toughness when stretched. The elastic nature of this network also accoimts for the exceptional resilience of cured rubber products. This resilience means less kinetic energy is lost as heat during repeated stress deformation. Products made from natural rubber are less likely than most other elastomers to fail from excessive heat buildup or fatigue when exposed to severe dynamic conditions. This has secured the place of natural rubber as the preferred sidewall elastomer in radial tires. 

In tires, carbon black is important because of the high flex fatigue and tear strength requirements of this product. Poor dispersion can result in premature cracking in both treads and sidewalls. In off-the-road tires poor dispersion results in excessive chip/chunk causing a significant loss in treadwear in addition to tread lug cracking which can lead to loss of an entire lug (radial tread bar). 

Figure 2.75 shows the constructions of a standard bias (diagonal) ply tire and a radial ply tire. The major components of a tire are bead, carcass, sidewall, and tread. In terms of material composition, a tire on an average contains nearly 50% of its weight in actual rubber for oil extended rubbers (typically containing 25 parts of aromatic or cycloparafiBnic oils to 75 parts of rubber), it is less. The remainder included carbon black, textile cord, and other compounding ingredients plus the beads. 

In the radial-ply tire, one or two plies are set at an angle of 90° from the center line and a breaker or belt or rubber-coated wire or textile is added under the tread. This construction gives a different tread-road interaction, resulting in a decreased rate of wear. The sidewall is thin and very flexible. The riding and steering qualities are noticeably different from those of a bias-ply tire and require different suspension systems. 

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