IN-SITU DETERMINATION OF EXOTHERMIC TRANSIENT PHENOMENA : ISOTOPIC LABELLING STUDIES - Download this document for free, or read online. Document in PDF available to download.

Abstract : Condensed phase kinetic deuterium isotope effects DIE and isotopic product exchange IPE represent two complementary, non-intrusive in-situ approaches for determining the transient mechanistic features which regulate the exothermic energy-releasing processes of energetic compounds and conventional explosives. Application of DIE and IPE to the complex highly exothermic events represented by decomposition, combustion, thermal explosion, and detonation selectively reveal the key microscopic transient mechanistic features and in some cases, may suggest a mechanistic commonality among these various events. DIE research investigations can identity the actual kinetic rate-limiting chemical reaction step and associated covalent bond rupture responsible for controlling the global energy release rate of a given exothermic event. The DIE approach also suggests the rate-controlling feature can change with the physical state of an energetic compound, which in turn is determined by an experiment-s design and externally applied boundary conditions. The IPE technique supplements DIE findings by showing the extent to which all covalent bonds are ruptured and infer the route of the chemical reactions by which transient species reform into products during an event-s overall exothermic process. Additionally, IPE can quantify the extent to which reactive transient species interactions are limited by diffusion in a pure compound or in a mixture of compounds during a detonation event. The unique microscopic mechanistic information obtained from both the DIE and IPE approaches also provides a scientific link between the microscopic and macroscopic behavioral characteristics encountered in the exothermic events of energetic compounds. The condensed phase DIE and IPE approaches are discussed, and cases where they bridge micro-and macroscopic issues are noted.

Author: S. Shackelford



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