Thermal decomposition of RDX in the presence of added K2B12H12

In an effort to understand the enhancement effect of boron hydride salts on the burning rates of nitramine gun propellants, the thermal decomposition of RDX has been studied, in the presence and absence of added K2B12H12, by two methods: 1) The samples are decomposed in an adapter attached to the inlet of a gas chromatograph, and the less-volatile products are examined by gas chromatography-mass spectrometry (GCMS). 2) The decomposition is quenched short of completion, and the nonvolatile residue is analyzed by high-pressure liquid chromatography. The pyrolysis-GCMS studies resulted in the chromatographic detection of the mechanistically significant 1,3,5-triazine as a product of RDX thermal decomposition; they also indicated that added K2B12H12 changes the product distribution obtained from RDX decomposition. The residue-analysis studies confirmed the formation of MRDX and related nitrosoamines in RDX decomposition and also produced evidence for chemical acceleration, by added K2B12H12, of the thermal decomposition of RDX. Some possible mechanisms for formation and breakdown of 1,3,5-triazine during RDX thermal decomposition are discussed. (Author)