Melting and Decomposition Temperatures

In the following the molar masses and the fundamental thermochemical data for the more commonly applied RTILs are presented. The data pertain, as far as could be ascertained, to carefully dried RTILs, with residual water contents below 0.01 mass %. The thermochemical data include the melting point, T, the onset of 

and the temperature of start of decompo-heat capacity and surface tension at 25 °C of 

Experimental values of the vapor pressures (indeed very small mPa to fractions of a Pa) of C mim NTp2 (n = 2,4, 6, 8) RTILs were obtained by Zaitsau et al. from Knudsen effusion cells [175]. The resulting molar enthalpies of vaporization (at 298 K) are respectively 135, 136, 140, and 150 kJ mol for these four RTILs, The enthalpies of vaporization were then estimated for a variety of l-alkyl-3-methylimidazolium RTILs with Cl , Bp4 , PFg, and NTF2 anions from the surface tensions r and molar volumes F by the expression A H = + B, Fig. 6.2, 

On the whole, then, the molar enthalpy of vaporization of the RTILs for which data are available are above 100 kJ mol and even above 200 kJ mol for NTF2 salts with the longer alkyl chain cations, which is a large endothermic value, considerably larger than that of common molecular solvents. This is, of course, directly related to the small vapor pressures of the RTILs. 

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The same decomposition path was observed for KBH by Stasinevich and Egorenko [178] except that the melting and decomposition temperatures were much higher (by about 100°C). We performed ball milling for 5 h on the as-received NaBH but without any effect on its decomposition behavior. This is most likely due to the fact that NaBH exhibits a high structural stability during... 

Table 5.5-6. Melting and Decomposition Temperatures of Important Constituents of Refractory Products.

Neglecting changes in the slope or magnitude of thermal properties that occur at phase changes such as the glass transition, melting, and decomposition temperatures of polymers, the temperature dependence oiK, p, and c for an amorphous polymer can be roughly approximated... 

Figure 1. (a) Effect of various salts on the melting temperature of collagen swoUen in water (b) Effect of LiCl on the melting and decomposition temperatures of poly-... 

Toluenesulfonamide Resin n Resins made by the interaction of toluene sulfonamide and formaldehyde. p-Toluenesulfonylhydrazide n A blowing agent similar to benzene-sulfonylhydrazide, but having higher melting and decomposition temperatures. 

A strong impression of the complexity of this technology is obtained by considering the melting and decomposition temperatures of the various chemical materials used in each process step (Table 2). 

The tellurium compounds are insoluble in dilute acids and alkali, and decompose in dilute nitric acid or cone, sulfuric acid. For melting or decomposition temperatures, see Table IV. No data are given for the selenium compounds, of which only a few, small crystals have as yet been obtained. 

Fig. 3.46 (a) The temperature of melting and decomposition peaks of NaBH for all composites from Figs. 3.44 and 3.45 as a function of the MgH content. Numbers in parenthesis show the number of multiple data points for this specific composition. Data for the (NaBH + Xwt%Mg) mixtures where Xwt% is an equivalent amount of Mg corresponding to the Mg decomposed from Xwt%MgHj are also included, (b) Analysis of the yield of MgB based on the Vajo et al. [196-198] model adopted for the (NaBH + MgH ) system... 

DSC experiments were conducted up to 500 and 600°C for the ball-milled mixtures of NaBH with 12, 55, 73 and 92 wt%Mg (DSC traces not shown here). The temperatures of melting and decomposition peaks of NaBH are plotted in Fig. 3.46a. It is seen that the data points for the equivalent content of 12, 55 and 73 wt%Mg follow quite closely the data points for MgH. Only data points for the equivalent content of 92 wt%Mg show slightly higher decomposition temperature than their MgH counterpart and lie slightly above the ROM line for MgH. This behavior is probably related to different mechanical properties of Mg and MgH which results in different abilities to particle and grain size reduction during the milling process as can be seen in Fig. 3.47. The particle size reduction of ductile... 

Table 6.13 Melting points and decomposition temperatures of potassium nitrate and potassium sulfate.

Differential thermal analysis (DTA) has provided a wealth of information regarding the thermal behavior of pure solids as well as solid mixtures [10]. Melting points, boiling points, transitions from one crystalline form to another, and decomposition temperatures can be obtained for pure materials. Reaction temperatures can be determined for mixtures, such as ignition temperatures for pyrotechnic and explosive compositions. 

Some of the important properties which are considered when choosing the ingredients for pyrotechnic formulations are density, hygroscopicity, melting and boiling points and decomposition temperatures, oxygen content of oxidizers, thermal conductivity of fuels and containers, nature of combustion products and toxicity etc. 

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