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Propellants containing nitroglycerine and ammonium perchlorate have been reported to have comparatively shorter shelf lives than analogous energetic materials without this oxidizer. However, investigation into the aging behavior of three compositions containing polyethylene glycol and nitroglycerine revealed that the propellant which included ammonium perchlorate degraded at a slower rate compared with the other materials. It was suggested that ammonium perchlorate might act as an oxygen inhibitor reducing the oxidation rate of the polyethylene glycol binder so decreasing the rate of the propellant decomposition. In addition, at temperatures of 80 °C or lower, ammonium perchlorate initially appears to hinder acid hydrolysis of nitroglycerine which also slows down the degradation of polyethylene glycol based propellant.

In part 1 of this paper, it was demonstrated that a nitroglycerine and polyethylene glycol based propellant containing ammonium perchlorate degraded at a slower rate at temperatures of 80 °C or less compared with the other two energetic materials studied which did not have this oxidizer present. It was suggested that ammonium perchlorate might act as an oxygen inhibitor reducing the oxidation rate of the polyethylene glycol binder which decreases the rate of propellant decomposition. In part 2, the specific interaction between ammonium perchlorate, nitroglycerine and polyethylene glycol is reported. It has been shown that at temperatures lower than 90 °C, if there is any uncured and unstabilised PEG present, nitroglycerine rapidly degrades in the presence of ammonium perchlorate but this is prevented if stabiliser is added. In addition, ammonium perchlorate initially appears to hinder acid hydrolysis of nitroglycerine which also slows down the degradation of polyethylene glycol based propellants. However, in the long term at low temperatures, or short term at higher temperatures, AP accelerates the decomposition of NG.

Measuring the vapor pressure of compounds such as nitroglycerine (NG) which have a low volatility has not been a straightforward task in the past. There are a wide range of values in the literature for the vapor pressure of NG and furthermore, there is little information regarding the vapor pressure of this compound above solid rocket propellant formulations. We have devised a new method for determining the vapor pressure of NG both above the pure material and solids containing this nitrate ester. The values obtained for pure liquid NG are in good agreement with some previously published values. It was also found that the vapor pressure of this compound is slightly lowered when it is incorporated into solid rocket propellant formulations.

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