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Einfluß der Phasenumwandlungen des Oktagens auf die mechanische Empfindlichkeit

: Eisenreich, N.; Engel, W.; Herrmann, M.

Fraunhofer-Institut für Chemische Technologie -ICT-, Pfinztal:
Technology of polymer compounds and energetic materials
Pfinztal: ICT, 1990 (Proceedings of the International Annual Conference of ICT 21)
ISSN: 0722-4087
Fraunhofer-Institut für Chemische Technologie (Internationale Jahrestagung) <21, 1990, Karlsruhe>
Fraunhofer ICT ()
mechanische Eigenschaft; Nitramin; Oktogen; Phasenumwandlung; Reibempfindlichkeit; Röntgenbeugung; Schlagempfindlichkeit; thermische Analyse

HMX crystallizes in four polymorphic phases, Beta, Alpha, Gamma and Delta. The Beta-phase is the most stable at room temperature. Alpha-HMX and the hydrated Gamma-phase are obtained under special crystallisation conditions, whereas Delta is the high temperature phase. The following stability ranges are reported. Beta to 163 degree C, Alpha 104-162 degree C, Gamma ca. 156 degree C, Delta 156-279 degree C. It has been found that the mechanical sensitivity of the Delta-phase is essentially higher than those of the other phases. For an estimation of the eventual handling risks the phase changes were prepared and investigated by fast x-ray diffraction during various temperature cycles. On heating the phases Beta, Alpha and Gamma change into phase Delta. In the case of Gamma changes of the lattice indicate that the hydrate water is lost before the transition. On cooling phase Delta changes back into the other phases with a very low rate. The phase is further stabilized by decomposition produ cts formed at temperatures above 200 degree C. The sensitivity of the phases against friction and impact were determined. An essentially higher sensitivity of phase Delta was found. Due to the low conversation rate this phase may exist even at room temperature for a long time. This must be taken into account, if handling risks of heated samples are considered.