Accession Number : ADA331299

Title :   Chemical Mechanisms of Shock Initiation of NTO.

Descriptive Note : Final rept. 15 Jun 94-14 Jun 97,

Corporate Author : SRI INTERNATIONAL MENLO PARK CA MOLECULAR PHYSICS LAB

Personal Author(s) : McMillen, D. F. ; Erlich, David C. ; He, Chun ; Becker, Christopher H. ; Shockey, Donald A.

PDF Url : ADA331299

Report Date : OCT 1997

Pagination or Media Count : 143

Abstract : A powerful analytical tool has been developed for in-situ, real-time measurement of the thermally and mechanically induced transient decomposition processes of energetic materials, and has been applied to the new, insensitive high explosive, nitro-1,2,4-triazol-5-one (NTO). Modification of the vacuum chamber of a laser-desorption mass spectrometry apparatus has enabled us to perform simple-shear and compressive fracture of pressed pellets directly beneath the sampling region: fragments spontaneously emitted from fractured NTO pellets are measured by single-photon ionization (SPI) time-of-flight mass spectrometry. The fracture-induced fragments of NTO are dominated by a single peak, m/z 99, which is completely absent in either the thermal- or laser-desorption spectra obtained in the same apparatus. This difference suggests that under the marginal stress of subcritical mechanical fracture, intermediates of mass 100 and/or 101 are diverted to the closed-shell, relatively stable species at mass 99, which then tends to accumulate, rather than going on to produce a next generation of unstable intermediates at m/z 85, 71, and 43. Thus, in its first use, this combination of techniques has enabled identification of intermediates not previously observed in NTO decomposition and allowed us to propose a reasonable sequence of reactions that involves all of these intermediates, reconciles a substantial portion of previous slow thermal decomposition data, and potentially explains the initiation insensitivity of NTO as resulting from diversion to a relatively stable 'dead-end' species.

Descriptors :   *INSENSITIVE EXPLOSIVES, *MASS SPECTROMETRY, REAL TIME, SHOCK(MECHANICS), ENERGETIC PROPERTIES, THERMAL DEGRADATION, KETONES, NITRO RADICALS, AZOLES, EXPLOSIVE DECOMPOSITION.

Subject Categories : Ammunition and Explosives
      Mechanics
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE