Ammonium nitrate pyrolants

Ammonium nitrate (AN) is a crystalline oxidizer that produces an oxidizer-rich gas when thermally decomposed according to  

When AN powder is mixed with a polymeric material, the oxygen gas produced by the decomposition of the AN powder reacts with the hydrocarbon fragments of the thermally decomposed polymeric material. The major combustion products are GO2 and H2O. Nitropolymers are not used as fuel components of AN pyrolants because of the reaction between the NO2 formed by their decomposition and the AN powder. This reaction occurs very slowly and damages the physical structure of the AN pyrolant. Instead, polymeric materials containing relatively high mass fractions 

The burning rates of AN pyrolants are of the order of 1-3 mm s at 10 MPa, which is very slow compared with AP pyrolants. Decomposition catalysts for AN powder, such as chromium trioxide (Cr203) and ammonium dichro-mate((NH4)2Cr207), need to be incorporated into AN pyrolants to aid their successive burning. Very unstable burning occurs without these catalysts. 

Since the combustion temperature of AN pyrolants is very low compared with other composite pyrolants, their specific impulse when used as rocket propellants is also low. However, they are used as gas generators for the control of various types of mechanics owing to the low temperature and low burning rate characteristics. 

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Ammonium nitrate (AN NH4NO3) is a white, crystalline material, the crystal structure of which varies with temperature.melting point is 442 K and its heat of fusion is 71.4 kj kg . Though the mass fraction of oxygen of AN is 0.5996, it is highly hygroscopic and absorbs moisture from the atmosphere to form liquid AN acid. This limits its application in propellants and pyrolants. However, AN is widely used as an oxidizer of explosives such as slurry explosives and ANFO (ammonium nitrate fuel oil) explosives. 

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