HIGH PERFORMANCE TYRE

In practice, a tyre will have an internal canvas and metal fibre structure which helps spread the load. The design of high performance tyres is not as simple as it might at first sight appear. 

Rubber industries produce various types of complicated products like tyre, cable, belt, seal, bearings, engine mounts, etc. The products are composed of rubber, plastics, fibre, metal, fillers and many other additives like antioxidants, accelerators, etc. Reverse engineering is a technique by which a rubber technologist can reconstruct the composition of the products based on thermal analysis. Dormagen [178] and Baranwal [179] reconstructed the formulation of a tyre, based on analyses of FTIR, spectra, thermal analysis and high performance liquid chromatography. 

Recent developments by DuPont in high performance car tyres have shown that inclusion of para-aramid as Kevlar EE, which is a pre-dispersed form of Kevlar pulp, in the rubber sidewall apex increases stiffness and improves cornering efficiency. The apex is part of the located radially outward of the tyre s bead (see Fig. 11.1 (a) and (b)). The EE stands for Engineered Elastomer and DuPont has introduced Kevlar EE into beltings, seals and gaskets, and bicycle tyres to improve resistance to abrasion, tear and puncture, modulus, and cut and chip resistance. ... 

This chapter is devoted to the use of particulate fillers in elastomers, which make greater use of fillers than do most other polymers, largely because fillers are able to improve greatly many of their properties to an extent not found in other composites. This is particularly true of their use in automobile tyres where the high performance levels taken for granted today would not be possible without very sophisticated carbon blacks and silicas. Because of the value of fillers to the elastomer industry, it is not surprising that the most advanced work on filler characterisation and links with composite properties have been carried out in this area. Many of the filler characterisation aspects have been covered elsewhere. This chapter concentrates on the basic principles of elastomer formulation and the role of fillers in this. 

Coupling agents are discussed in detail in Chapter 4. In rubber systems, coupling agents can improve a wide range of properties, so much so that they are indispensible for high performance products such as power cable [9] and tyres [10,11]. 

Natural rubber (NR) is a classic elastomer with good processability and excellent mechanical properties. It is widely used in various applications such as automobiles, gloves, tyres and seals. With the increasing demand for NR composite materials for applications at high temperatures with high performance, for example in the automobile industry, there has long been increasing interest in NR-based composites blended with other rubber systems. ... 

In road pavements, high performance concrete with carefully selected aggregate and compressive strength up to 135 MPa exhibited a level of abrasion resistance from studded tyres similar to massive granite. According to laboratory tests, this concrete may last four times longer than traditional concrete of 55 MPa. The addition of a small amount of steel and polypropylene fibres improves crack control in elements reinforced with traditional steel bars, for example, in deep beams where steel fibres partly replace stir-... 

The Bayer Tear Analyser is described, and examples are presented of its use in predicting the cut growth performance of rubber compounds for high performance car tyre treads, car and truck tyre breakers, radial truck tyre treads and truck tyre inner liners. Good correlation between the test results and the service performance of various tyre components is demonstrated. The application of the machine in optimising tyre inner liner formulations based on bromobutyl robber and blends of bromobutyl and butyl rubber is also described. 6 refs. 

Guzman and co-workers [27] investigated whether it is possible to use waste tyre crumb as a replacement for zinc oxide as an activator in the sulfur vulcanisation of natural rubber (NR). They used the unsaturated organic compound squalene as a model compound for NR in their work, and followed the course of the vulcanisation reaction using the analytical technique high-performance liquid chromatography. The results confirmed that waste rubber crumb was an alternative to zinc oxide as an activator in the curing of NR compounds by sulfur-based cure systems. 

Polybutadiene is produced by solution polymerisation, and one important feature governing the performance of the resultant polymer is the cis 1,4, and 1, 2 vinyl contents. High cis 1,4 polymers (>90%) have a Tg around -90 °C, and hence exhibit excellent low temperature flexibility only exceeded by the phenyl silicones. They also exhibit excellent resilience and abrasion resistance unfortunately the high resilience gives poor wet grip in tyre treads, and hence this rubber finds limited use as the sole base for such compounds. 

When a fully inflated car tyre is allowed to deflate, the air streaming through the nozzle is cold to the touch. The pressure of the air within the tyre is fairly high, so opening the tyre valve allows it to leave the tyre rapidly - the air movement may even cause a breeze. We could feel a jet of cold air on our face if we were close enough. As it leaves the tyre, this jet of air pushes away atmospheric air, which requires an effort. We say that work is performed. (It is a form of pressure-volume work, and will be discussed in more depth later, in Section 3.2.)... 

Fillers. Carbon black, clays, calcium carbonate, silica, etc. are typical rubber fillers. Carbon black is used in relatively high proportions to improve the strength of the rubber. The performance of carbon black incorporated into rubber largely depends on its particle size distribution. Tyres contain over 30 wt% of carbon black. 

These are shown in Table 13.12. All these areas are currently growing at the extent of 2-3% per annum and this trend is expected to continue especially relevant is the growing use of electrically powered vehicles for which PU is often superior as a tyre material at the low speeds and relatively high loads involved. Future advances of PU elastomers in this field will depend upon the development of tyres with improved dynamic performance through lower hysteresis and better traction. 

These are now manufactured in Europe (Polyair Machineban GmbH, Austria) from castable polyurethane and although inferior in performance, especially at high speeds, to conventional textile and wire-reinforced rubber tyres, have sufficient applications for limited production to be established. 

Steel cord has been the main reinforcing material for tyres, hoses and conveyor belts for many decades, indeed the first steel reinforced tyres appeared over ninety years ago. However, it was not until the emergence of radial tyres that steel cord became a common form of reinforcement and understandably the adhesion between brass-coated steel cord and rubber compound became a significant factor governing the performance and durability of car and truck tyres. Therefore, it is necessary to achieve a high level of adhesion and sustain this level throughout the service history of the tyre. 

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