INDEX temperature stability

High-temperature stability Excellent chemical resistance Low surface energy Low water absorption Limiting oxygen index (LOI) > 95... 

Figure 34 shows a comparison of temperature stability in terms of TGA at different isocyanate indices (16). The results indicate that the higher the isocyanate index, the higher the temperature resistance. 

A wide linear response range and high flow rate capability, are desirable features in a detector for preparative-scale chromatography. Problems with temperature stability (refractive index) and pressure pulses (UV detector) are less important because of the high sample concentrations present in the mobile phase. Some analytical detectors have interchangeable flow cells, which allow replacement of the analytical cell with one of... 

PROPERTIES OF SPECIAL INTEREST Low-temperature flexibility and high-temperature stability, high oxygen index and low flame spread rate, hydrophobic (low surface tension), good Ccubon solvent resistance, biocompatibility, mesophase formation, and polymorphism. 

Kusan-Bindels and Friedrichs [57] have discussed the measurement of this property in rigid polyisocyanurate foams. An increase in the thermal insulation index of this polymer improves temperature stability and mechanical properties, even at 250 °C. 

Chlorinated benzenes, because of their much higher UV cutoffs (>285 min versus 233 nm for DCM) and high cost (more than twice the cost of DCM), are rarely used in HPLC standard methods. However, when systems in which tempera hires in excess of 70°C are needed (in order to solubilize analytes) and a refractive index detector or methods that employ UV detection where a high wavelength is used, the temperature stability of the chlorinated benzenes offers a practical alternative. 

Partial substitution of Ti02 pigments with double the quantity of ZnS does not impair brightness, pigment dispersion, or melt flow index of a masterbatch, but reduces friction and abrasion and increases temperature stability. It can thus act as a processing aid, especially in linear LDPE. 

Nonetheless, owing to its temperature stability, dopabUity and widely tunable optical behavior, amorphous SiC doped with hydrogen (a-SiC H) has been investigated for its application in photovoltaic devices. One of several structural renderings of amorphous SiC is shown in Figure 11.9. In this case, the refractive index can be varied from 2.3 to 3.7, and the band gap from 2.4 to 2.0eV, simply by altering a few parameters of the plasma-enhanced CVD technique that is used to deposit an amorphous silicon carbide layer with low defect density onto, for example, a substrate of RSiC. Attention has also been focused on the surface passivation performance of layers deposited on crystalline siUcon. Indeed,... 

TABLE 4 Enthalpies and stabilization indexes of stabilized samples in different temperatures (constant time of Ih, and heating rate of 1 °C/min). 

Fig. 4 shows the dynamic behavior of the particle (refractive index n=1.59, radius r=5pm, density p=1.05 g/cm3) in 20mW laser beams with a cycle period of 250msec. In this case, the fiber trap was formed using a temperature stabilized cw diode laser, pigtailed with single-mode fiber. 

Large range of service temperatures Constant viscosity (viscosity index) Pour point, thermal stability... 

It is important to know whether a polymer will be stable, that is, whether it will not decompose at a given temperature. There are several measures of thermal stability, the most important of which (from an economic standpoint) is the Underwriters Laboratories (UL) temperature index. 

Such a value for relative temperature index will be specific to a particular grade of a polymer, sometimes even to a specific colour. The difference between grades of a particular species of polymer can be substantial, depending both on the variation in the inherent stability of a material between differing manufacturing methods and also on the type and amount of additives used. It is possible to obtain from the Laboratories a Generic Temperature Index to cover a species of material but this will usually be considerably lower than for many of the individual grades within that species. 

As with the polysulphones, the deactivated aromatic nature of the polymer leads to a high degree of oxidative stability, with an indicated UL Temperature Index in excess of 250°C for PEEKK. The only other melt-processable polymers in the same league are poly(phenylene sulphides) and certain liquid crystal polyesters (see Chapter 25). 

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