Determination of Gaseous and Solid Decomposition Products of Nitroguanidine

Abstract

AbstractIn spite of many publications dealing with the thermal decomposition of the cyclic nitramines RDX and HMX, the decomposition behavior of nitroguanidine (nigu), especially in the low temperature range, has not been investigated fundamentally in the past. Because nitroguanidine is an important explosive component for triple base propellants, a better understanding of the thermal decomposition at low temperatures is of interest.For example, aging studies of triple base propellants exhibited a different decomposition behavior from single and double base propellants. Therefore nigu is supposed to influence the safe life time of propellants containing nitric acid esters.The investigations of the decomposition of nigu published in the past, have been performed at temperatures between 190°C and 240°C. The aim of this work was to study the decomposition behavior of nigu at temperatures as low as possible.In this connection, temperatures between 110°C and 240°C have been used. In this temperature range, nitroguanidines with different grain sizes have been investigated by measuring the weight loss and analyzing the decomposition gases by mass spectrometry. Also solid residues, like ammeline and melamine, remaining after the degradation tests were analyzed quantitatively by using high performance liquid chromatography. The formation of melamine and ammeline was found to depend strongly on the amount of the weight loss of nigu. The better stability behavior of triple base propellants is possibly due to the formation of NH3 which is being formed in the decomposition process of nigu. Ammonia reacts with nitric oxides and behaves therefore similar as a stabilizer.