Thermal stability at elevated temperatures

Calcium sulfate exhibits high thermal stability. At elevated temperatures, it occurs in anhydrous form. The dihydrate loses its water molecules upon strong heating. When ignited with charcoal, it is reduced to calcium sulfide ... 

The most important attributes of this invention are high impulse performance coupled with high exit temperature on primary combustion and favorable boron species in the primary motor exhaust. The system is also insensitive to impact and possesses excellent thermal stability at elevated temperatures. Additionally, the system is readily castable since the addition of solid oxidizers is not required. Further, high flexibility in the ballistic properties of the gas generator can be achieved by the addition of solid oxidizers such as ammonium nitrate, ammonium perchlorate, hydroxylammonium perchlorate, potassium perchlorate, lithium perchlorate, calcium nitrate, barium perchlorate, RDX, HMX etc. The oxidizers are preferably powdered to a particle size of about 10 to 350 microns [13]. 

In order to use semiconductive metal oxides as an oxygen sensor, both thermal stability at elevated temperatures and atmospheric stability under reductive environments are required for reproducibility and accuracy of the sensor. 

Struis RPWJ, Quintilii M, and Stuck S. Feasibility of Li-Nafion hollow fiber membranes in methanol synthesis Mechanical and thermal stability at elevated temperature and pressure. J Membr Sci 2000 177(l-2) 215-223. 

Although a very good cathode-active material, LiCo02 has several disadvantages, such as high cost (due to the limited natural source of the cobalt element), toxicity of cobalt, and limited specific capacity, thermal stability at elevated temperatures, etc. Therefore,... 

The development of new Li salts to replace the commonly used LiPFg, which is not stable with water and has low thermal stability at elevated temperatures, continues to draw attention. A newly developed Li salt, lithium bis(oxalato) borate shows a number of advantages such as higher thermal stability at elevated temperatures, capability for improving compatibility between the graphite anode and PC-based electrolytes, and lower cost. ... 

In 2008, Hwang and coworkers reported the use of homoleptic bis-chelate tet-racarbene Pd(II) complex [( "CC" )2Pd][BF4]2 (Figure 4.14) as precatalyst for the Mizoroki-Heck reaction [49]. The complex showed excellent air and thermal stability at elevated temperatures, and proved to be an excellent precatalyst with potential recyclability. 

Sky pel is the registered trademark of a polyester-based thermoplastic engineering elastomer manufactured by SK Chemicals [9]. It can be processed in a wide variety of products from ultra small precision parts to spread sheets by injection, extrusion, and others. Skypel is a block copolymer consisting of hard crystalline phase and soft amorphous phase, and the relative proportions of the two phases determine the material properties. Skypel , ranging over a broad hardness spectrum, offers excellent features such as toughness, resilience, resistance to creep, impact and flexural fatigue, flexibility at low temperatures, thermal stability at elevated temperatures, and resistance to many industrial chemicals, oils, and solvents. Table 9 shows some typical properties of Skypel . 

The reactions depicted in Fig. 32 are most often carried out at low temperatures. The incursion of a thermal process at elevated temperatures has occasionally been observed. In some cases the thermal oxygenation products are identical to the photochemical products and in other cases are different. For example, when 2,3-dimethyl-2-butene/02 NaY is warmed above — 20 °C a reaction was observed which led to pinacolone (3,3-dimethyl-2-butanone) as the major product.98,110 Pin-acolone is not formed in the photochemical reaction at the same temperature. On the other hand, identical products were observed in the thermal and photochemical intrazeolite oxygenations of cyclohexane.114,133 135 These intrazeolite thermal processes occur at temperatures well below that necessary to induce a classical autooxidation process in solution. Consequently, the strong electrostatic stabilization of oxygen CT complexes may also play a role in the thermal oxygenations. Indeed, the increase in reactivity of the thermal oxygenation of cyclohexane with increasing intrazeolite electrostatic field led to the conclusion that initiation of both the thermal and photochemically activated processes occur by the same CT mechanism.134 Identical kinetic isotope effects (kH/kD — 5.5+0.2) for the thermal and photochemical processes appears to support this conclusion.133... 

Polyesters usually have good thermal and oxidative stability (up to 200°C) but have poor hydrolytic stability at elevated temperatures. 

The inclusion of heat stabilizers is essential to protect the system against thermal decomposition at elevated temperatures during processing. For this purpose, tin carboxylate esters or liquid calcium-zinc stabilizers are preferred. Thio-tin compounds are very effective as heat stabilizers but must be regarded with caution, bearing in mind that they can lead to unpleasant and unacceptable residual odours. Secondary stabilizers that can be used include epox-idized soya bean oil. 

The exposed compounds also show a slow decrease In resistance to thermal oxidation at elevated temperatures, when measured by conventional techniques of oxygen uptake or thermal analysis. Table II shows typical thermal analysis data on samples weathered In New Jersey for 10 years. Similar measurements on compounds exposed for 30 years show that some thermal oxidative stability still remains In the bulk material. 

A similar procedure was developed to grow ZSM-5 crystals in situ on a molybdenum support [245]. The high thermal conductivity (138 W mK 1) and the high mechanical stability at elevated temperatures of the molybdenum support allow the application of ZSM-5 coatings in microreactors for high temperature processes involving large heat effects. The effect of the composition of the synthesis mixture on... 

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