Relative thermal indices table

The Relative Thermal Index is based on a method developed by Underwriters Laboratories. It is defined as the temperature at which a physical property retains 50 % of its initial value for a period of 60,000 hours. Relative thermal index temperatures (in °C) are given for some common plastics in Table 1. 

Compared to other engineering plastics, PPS compounds exhibit a superior combination of both elevated-temperature mechanical integrity and long-term resistance to thermal degradation. Table 15.8 compares the elevated-temperature performance of various reinforced engineering plastics as indicated by the heat deflection temperature and UL relative thermal index (RTI). 

Relative Thermal Index Based Upon Historical Records. Through experience gained from testing a large volume of complete products and insulating systems over a long period, UL has established relative thermal indices on certain types of plastics. These fundamental temperature indices are applicable to each member of a generic material class. Table 3-1 lists the temperature indices based on past on past field test performance and chemical structure. 

Table 5.48 Relative temperature index (RTI) according to UL 746 and temperature index (TI) at 5000 h and 20,000 h, respectively. Thermal Endurance Profile (TEP) according to lEC 216 and upper temperature limits (without mechanical load) for various polyamides short-term loaded once or several times for less than an hour, long-term permanent load over years [ 14], [86]...

Fused silica is by far the primary optical material for lens manufacturing. Its mechanical and thermal properties are well known, and its grinding and polishing infrastructure are well established. It is relatively inexpensive and has good index homogeneity over large areas. Lens-grade fused silica, however, is an expensive material. The temperature-dependent properties of fused silica are summarized in Table 13.7. 

More specific and sophisticated methodology has been developed recently to elucidate how lipid oxidation products and other bioactive compounds act in the complex mechanism of LDL oxidation. A large amount of work has been published recently on the GC-MS or LC-MS analyses of cyclic oxidation products of arachidonate described as isoprostanes in biological samples as an index of oxidative status. Because the level of arachidonate in LDL and blood is relatively small (Table 13.2), much effort has been made to use instrumental means to improve the sensitivity required to analyse isoprostanes. This instrumental approach is still beyond the capability of many laboratories, however. LC-MS has the advantage of direct measurements of isoprostanes in contrast to GC-MS (see Chapter 6), which requires the use of two or three thermally stable derivatives. On the one hand, LC-MS still requires purification by reversed-phase solid-phase extraction, followed by TLC to remove impurities, but this step can also be avoided if one can invest in a highly selective MS/MS system. On the other hand, the well-established methodology to measure oxidation products of linoleate, which is present in LDL at levels about seven fold higher than that of arachidonate (Table 13.2), is much more within the capability of many laboratories than the more expensive LC-MS and GC-MS and MS/MS approaches required for isoprostanes. 

The general designation (i.e., chemical name, CAS registry number, UN number), the relative atomic and molar mass, the physical properties (i.e., density, viscosity), thermal properties (i.e., molar heat capacities, latent enthalpies, and thermal conductivity), optical properties (e.g., refractive index), along with properties important for health and safety (i.e., flammability limits, ignition temperature, toxicity) of some important gases are reported in Tables 19.15-19.17. 

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