Nitroglycerine melting temperature

The freezing and melting temperatures of these transformations have been established by Kast [14] who also observed that very pure nitroglycerine is transformed on freezing mainly into the labile crystals, whereas a less pure sample often crystallizes in the stable form.,... 

It is a very powerful explosive (the rate of detonation at a density of 0.80 in a cartridge 10 mm dia. is 4060 m/sec, and the lead block expansion is 390 cm3) but it is not sufficiently stable since its ignition temperature is only slightly above its melting point. It is also very sensitive to impact—like nitroglycerine. 

There are two modifications of nitroglycerine, differing in freezing point and crystalline forms. With respect to crystal structure the form melting at the lower temperature represents a labile form (Fig. 6) which can be transformed spontaneously into the higher melting stable form of nitroglycerine (Fig. 7). 

Since it is a soft material, melting at a low temperature, lead is easily welded. In nitroglycerine plants, parts of equipment of lead can be constructed without difficulty in the factory s own workshops from sheet lead 10-15 mm thick. 

Dinitrodiglycol exists in two crystalline forms—a stable form melting at a temperature of +2°C and a labile one whose melting point is —10.9°C (thus resembling nitroglycerine). At 20°C it is an oily liquid of density 1.385 g/cm3, boiling and simultaneously decomposing at 160°C. Its refractive index is 1.4517 (at 20°C). 

The problems of phase transition always deeply interested Ya.B. The first work carried out by him consisted in experimentally determining the nature of memory in nitroglycerin crystallization [8]. In the course of this work, questions of the sharpness of phase transition, the possibility of existence of monocrystals in a fluid at temperatures above the melting point, and the kinetics of phase transition were discussed. It is no accident, therefore, that 10 years later a fundamental theoretical study was published by Ya.B. (10) which played an enormous role in the development of physical and chemical kinetics. The paper is devoted to calculation of the rate of formation of embryos—vapor bubbles—in a fluid which is in a metastable (superheated or even stretched, p < 0) state. Ya.B. assumed the fluid to be far from the boundary of absolute instability, so that only embryos of sufficiently large (macroscopic) size were thermodynamically efficient, and calculated the probability of their formation. The paper generated extensive literature even though the problem to this day cannot be considered solved with accuracy satisfying the needs of experimentalists. Particular difficulties arise when one attempts to calculate the preexponential coefficient. 

Belyaev s experimental studies related to liquid secondary explosive materials—methylnitrate, nitroglycol, nitroglycerine—and to secondary explosive materials which are solid at room temperature, but which melt when ignited—trotyl, picric acid, etc. 

The dinitroglycerin obtained by the nitration of glycerin is a colorless, odorless oil, more viscous and more volatile than nitroglycerin. It causes the same kind of a headache. It has a specific gravity of 1.51 at 15°, boils at 146-148° at 15 mm. with only slight decomposition, and solidifies at —40° to a glassy solid which melts if the temperature is raised to —30°. It is readily... 

Nitroglycerine has two modifications with different freezing points and crystalline forms. For the crystalline structure, the molten phase at low temperature is not stable. It can be spontaneously converted to the stable phase with high melting point. The freezing points of nitroglycerine obtained in different references are summarized in Table 5.27. 

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