Ammonium perchlorate, decomposition high temperature

A considerable amount of research has been conducted on the decomposition and deflagration of ammonium perchlorate with and without additives. The normal thermal decomposition of pure ammonium perchlorate involves, simultaneously, an endothermic dissociative sublimation of the mosaic crystals to gaseous perchloric acid and ammonia and an exothermic solid-phase decomposition of the intermosaic material. Although not much is presently known about the nature of the solid-phase reactions, investigations at subatmospheric and atmospheric pressures have provided some information on possible mechanisms. When ammonium perchlorate is heated, there are three competing reactions which can be defined (1) the low-temperature reaction, (2) the high-temperature reaction, and (3) sublimation (B9). 

Accumulatory pressure measurements have been used to study the kinetics of more complicated reactions. In the low temperature decomposition of ammonium perchlorate, the rate measurements depend on the constancy of composition of the non-condensable components of the product mixture [120], The kinetics of the high temperature decomposition [ 59] of this compound have been studied by accumulatory pressure measurements in the presence of an inert gas to suppress sublimation of the solid reactant. Reversible dissociations are not, however, appropriately studied in a closed system, where product readsorption and diffusion effects within the product layer may control, or exert perceptible influence on, the rate of gas release [121]. 

Fig. 17. Unified reaction scheme for the thermal decomposition of ammonium perchlorate, proposed by Jacobs et al. [59,925,926], In the low temperature reaction, the interaction occurs between adsorbed species (a) whereas the high temperature reaction and sublimation process involved volatilization intermediates (g). X] and X2 represent mixtures of intermediates.

An important feature of ammonium perchlorate propellants is their decomposition a high temperature. Differential thermal analysis of Nll. (1(>4 is given in l ig. 125, according to Snrner 4]. It can be seen that appreciable decomposition occurs at temperatures lower than the main exotherm. 

Ammonium perchlorate decomposes over the wide temperature range of 200 C to 440 C by two different mechanisms.[40, 43] Between 200 C and 300 C the decomposition takes place by an autocatalytic process which ceases after about 30% decomposition. The decomposition proceeds via a second mechanism in the high-temperature regime (300-430°C), where the reaction is not autocatalytic and the decomposition goes to completion. Bircumshaw and Newman [47, 48] were the first to report that simultaneous with decomposition, sublimation of AP takes place throughout both the low- and the high-temperature decomposition regions. 

Baumgartner et al. (9) compared the thermal and mechanical degradation of filled and unfilled elastomers. They were particularly interested in the long-term aging and fatigue behavior of solid propellants filled with ammonium perchlorate or potassium chloride. They reported that the mechanisms for thermally and mechanically induced decomposition of the propellant binder appear equivalent. At low temperatures, mechanical processes control the decomposition rates of the polymers, whereas thermal processes control the decomposition at high temperature. They further note that, "Equivalence of thermal and mechanical degradation... 

NITROCARBOL (75-52-5) Forms explosive mixture with air (flash point 95°F/35°C). Thermally unstable. Shock, friction, pressure, or elevated temperature above 599°F/315°C can cause explosive decomposition, especially if confined. Violent reaction with strong oxidizers, alkyl metal halides, diethylaluminum bromide, formic acid, methylzinc iodide. Contact with acids, bases, acetone, aluminum powder, amines, bis(2-aminoethyl)amine, haolforms make this material more sensitive to explosion. Reacts, possibly violently, with ammonium hydroxide, calcium hydroxide, calcium hypochlorite, 1,2-diaminomethane, formaldehyde, hexamethylbenzene, hydrocarbons, hydroxides, lithium perchlorite, m-methyl aniline, nickel peroxide, nitric acid, metal oxides, potassium hydride, potassium hydroxide, sodium hydride. Mixtures with ammonia, aniline, diethylenetriamine, metal oxides, methyl amine, morpholine, phosphoric acid, silver nitrate form shock-sensitive compounds. Forms high-explosive compound with urea perchlorate. Mixtures with hydrocarbons and other combustible materials can cause fire and explosions. Attacks some plastics, rubber, and coatings. 

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