Tire materials

Unsaturated Polyester Resins. Unsaturated polyester resins are widely used as fiber-reinforced plastics, coating materials, tire cords, films, and casting or molding resins. Organic titanates such as TYZOR TPT, TYZOR TBT, or TYZOR TOT can be used to catalyze the preparation of the resins, which involves the polyesterification of a mixture of a- and p-unsaturated polybasic acids, such as maleic or fumade acid, and alicydic polybasic acids, such as adipic or isophthalic acid with polyhydroxyalcohols (489). 

The stated 25 % recycled content provision is not a limitation of the technology or regulations, but a business choice with the economic consequences shown. Eor processes tliat can use recycled PET more cheaply than those which use virgin material, tire percentage-recycled content may be greater than 25 %. The 25 % content level has ttaditionally been seen as sufficiently high enough to represent substantial content. Marketers who advertise recycled content considerably less than 25 % are frequently met with scorn and derision. 

As the body of vehicle accident reconstruction experience is growing, so are libraries of information on such things as the characteristics of vehicle materials, tires, driving surfaces, and visibility factors. Data on causative factors are being amassed and used to make recommendations to improve transportation safety at both the manufecturing and the legislative levels. 

Materials. Tire compounds contain the following generalized ingredients in the approximate proportions noted. Industry practice is to formulate starting with 100 parts per hundred weight of the rubber (phr). Table 22 offers examples for various treads. 

In this case the slot length is about 4 times the probe diameter. The material chosen has a penetration depth of 0.8991 mm at tire given frequency of 60.9 kHz. The slot depth is 3 times the penetration depth. 

In the absence of skidding, the coefficient of static friction applies at each instant, the portion of the tire that is in contact with the pavement has zero velocity. Rolling tire friction is more of the type discussed in Section XII-2E. If, however, skidding occurs, then since rubber is the softer material, the coefficient of friction as given by Eq. XII-5 is determined mainly by the properties of the rubber used and will be nearly the same for various types of pavement. Actual values of p, turn out to be about unity. 

The situation is complicated, however, because some of the drag on a skidding tire is due to the elastic hysteresis effect discussed in Section XII-2E. That is, asperities in the road surface produce a traveling depression in the tire with energy loss due to imperfect elasticity of the tire material. In fact, tires made of high-elastic hysteresis material will tend to show superior skid resistance and coefficient of friction. 

Certain materials, most notably semiconductors, can be mechanically cleaved along a low-mdex crystal plane in situ in a UFIV chamber to produce an ordered surface without contamination. This is done using a sharp blade to slice tire sample along its preferred cleavage direction. For example. Si cleaves along the (111) plane, while III-V semiconductors cleave along the (110) plane. Note that the atomic structure of a cleaved surface is not necessarily the same as that of the same crystal face following treatment by IBA. 

The first application of the time-resolved CIDNP method by Closs and co-workers involved tire Norrish 1 cleavage of benzyl phenyl ketone [24, 25]. Geminate RPs may recombine to regenerate the starting material while escaped RPs may fonn the starting ketone (12), bibenzyl (3), or benzil (4), as shown below. 

Light microscopy is of great importance for basic research, analysis in materials science and for the practical control of fabrication steps. Wlien used conventionally it serves to reveal structures of objects which are otherwise mvisible to the eye or magnifying glass, such as micrometre-sized structures of microelectronic devices on silicon wafers. The lateral resolution of the teclmique is detennined by the wavelength of tire light... 

Chaimelling only requires a goniometer to inelude the effeet in the battery of MeV ion beam analysis teelmiques. It is not as eonnnonly used as tire eonventional baekseattering measurements beeause the lattiee loeation of implanted atoms and the aimealing eharaeteristies of ion implanted materials is now reasonably well established [18]. Chaimelling is used to analyse epitaxial layers, but even then transmission eleetron mieroseopy is used to eharaeterize the defeets. 

---