Supervisor’s Foreword
This thesis describes a truly innovative approach to rationalize and predict for the
first time the relative impact and shock sensitivities to initiation of a range of
energetic materials. Energetic materials (exemplified by explosives, propellants, gas
generators, and pyrotechnics) release heat and/or gaseous products at a high rate
upon stimulus by heat, impact, shock, spark, etc. They have widespread military
and civilian uses that include munitions, mining, quarrying, demolition, emergency
signaling, automotive safety, and space exploration. One of their most important
properties is sensitivity to accidental initiation during manufacture, transport,
storage, and operation; Consequently, this has important implications for their safe
and reliable use. The prediction of the sensitivity of energetic materials to initiation
by shock and impact is widely recognized as being very challenging and represents
a significant barrier for the design, discovery, and preparation of safer materials.
The research described in this thesis highlights how experimental and computational methods have been used to develop various models with increasing levels
of complexity and sophistication, which can be used rationalize the experimentally
observed sensitivities of a range of energetic materials to initiation by impact and
shock. A key aspect of the research has been to correlate successfully the experimentally measured sensitivities with knowledge of crystal structures, vibrational
properties, and energy-transfer mechanisms. In particular, the importance of the
various mechanisms of vibrational up-pumping of energy within the crystalline
solids has been highlighted. These correlations have been demonstrated for several
classes of compounds including azides and nitramines, thereby highlighting the
wide applicability of this approach. This work therefore opens the door to a new,
fully ab initio approach for the design of safer energetic materials based solely on
knowledge of their solid-state structures.
The introductory chapter of this thesis provides a very accessible introduction to
energetic materials and the various methods that have been attempted previously in
order to rationalize and predict sensitivities to initiation. Chapter 2 describes the
experimental and computational approaches that have been employed during this
research. The subsequent chapters detail the results of these studies on a series of
compounds, demonstrating excellent clarity of expression and a highly developed
v
This thesis describes a truly innovative approach to rationalize and predict for the
first time the relative impact and shock sensitivities to initiation of a range of
energetic materials. Energetic materials (exemplified by explosives, propellants, gas
generators, and pyrotechnics) release heat and/or gaseous products at a high rate
upon stimulus by heat, impact, shock, spark, etc. They have widespread military
and civilian uses that include munitions, mining, quarrying, demolition, emergency
signaling, automotive safety, and space exploration. One of their most important
properties is sensitivity to accidental initiation during manufacture, transport,
storage, and operation; Consequently, this has important implications for their safe
and reliable use. The prediction of the sensitivity of energetic materials to initiation
by shock and impact is widely recognized as being very challenging and represents
a significant barrier for the design, discovery, and preparation of safer materials.
The research described in this thesis highlights how experimental and computational methods have been used to develop various models with increasing levels
of complexity and sophistication, which can be used rationalize the experimentally
observed sensitivities of a range of energetic materials to initiation by impact and
shock. A key aspect of the research has been to correlate successfully the experimentally measured sensitivities with knowledge of crystal structures, vibrational
properties, and energy-transfer mechanisms. In particular, the importance of the
various mechanisms of vibrational up-pumping of energy within the crystalline
solids has been highlighted. These correlations have been demonstrated for several
classes of compounds including azides and nitramines, thereby highlighting the
wide applicability of this approach. This work therefore opens the door to a new,
fully ab initio approach for the design of safer energetic materials based solely on
knowledge of their solid-state structures.
The introductory chapter of this thesis provides a very accessible introduction to
energetic materials and the various methods that have been attempted previously in
order to rationalize and predict sensitivities to initiation. Chapter 2 describes the
experimental and computational approaches that have been employed during this
research. The subsequent chapters detail the results of these studies on a series of
compounds, demonstrating excellent clarity of expression and a highly developed
v