High Explosives
Explosive Materials
The purpose of AWE’s Explosive Materials group is to develop new explosive ingredients and formulations, and to characterise existing explosives.
The new materials team undertakes synthesis of novel explosive ingredients, new energetic polymers and explosives, the synthesis of inert polymers, and the development of formulations of explosives and polymers. The new materials team is also particularly active in AWE Technical Innovation Fund (ATIF) programmes.
Explosive materials are characterised during development using various techniques, including Thermogravimetric Analysis (TGA) to assess stability, Gel-Permeation Chromatography (GPC) and/or Mass Spectroscopy to measure molecular weight, density measurement, Differential Scanning Calorimetry (DSC), Multinuclear Nuclear Magnetic Resonance (NMR), Infra-Red Spectroscopy (IR) and Scanning Electron Microscopy (SEM).
The majority of this work is carried out at AWE in an explosive-licensed research facility, however the team also manages external contracts placed with academia and industry, in support of in-house synthetic and analytical programmes. Patents are arising from the innovative research programme actively pursued by the team.
Ageing Assessment
The Ageing Assessment team undertakes real-time and accelerated ageing studies in support of warhead life assessment. The main goals of ageing studies are to gain an understanding of the science of explosives ageing, and to develop a predictive model for ageing effects in service. This involves the setting up and management of a variety of accelerated-ageing experiments, together with assessment of material arising from in-service surveillance programmes.
Non-isothermal ageing techniques for explosive materials are being developed with the aid of experience gained by Surrey University working on an AWE-funded EMR contract, which focused on the use of tritium labelling / tracer techniques as an alternative method for the characterisation and monitoring of nitrocellulose degradation.
Chemical Characterisation
The Chemical Characterisation team investigates components using a range of modern analytical techniques. Gel-permeation chromatography (GPC) is used to quantify molecular-weight changes in energetic binder systems, and high-performance liquid chromatography (HPLC) to investigate stabiliser depletion rates.
Traditional methods of analysis are still required in some instances, such as composition analysis. The team is constantly looking towards improved characterisation and analytical techniques for energetic materials, which has led to a long-term collaboration with the Defence Ordnance Safety Group (DOSG).
Hazard Assessment
The Hazard Assessment Team is responsible for assessing the potential for unintended explosion. Explosives produce large amounts of energy when intentionally detonated, but associated with this is the potential for unintentional release of energy as a result of stimuli, such as impact, friction, electric discharge, sparks, heat and flame.
Tests are conducted on both powders and pressed explosive to assess the sensitiveness, which is the threshold of reaction to stimuli, and the explosiveness, which is the magnitude of an event if it occurs. The dimensions and shape of the explosive particles in pressed polymer-bonded explosives influences the packing and filler surface area, which in turn affects the mechanical, hazard and detonics properties.