“Environmentally Friendly Energetic Processing Via Resonant Acoustic® Mixing (RAM)” by Dr. Eric Beckel
Plastic-bonded explosives (PBXs) are critical secondary energetics due to their ability to generate high theoretical maximum density (TMD) materials that are stabilized via elastomeric polymers to increase the insensitive nature of the explosive. PBXs are currently manufactured in significant quantities, generally via slurry or cast-cure processes. However, these processes generate significant amounts of energetically contaminated waste and scrap, which requires some type of remediation to avoid environmental release issues. In this research, we utilize Resonant Acoustic® Mixing (RAM) technology to generate secondary explosive pressing powder and cast-cure formulations that minimize the use of processing and cleaning solvents and reduce the amount of energetic scrap and waste. For the pressing powder work, we are developing processes for the waterless generation of these formulations that only use small amounts of non-hazardous air polluting (non-HAP) solvents that can be recovered and reused. The developed processes ensure that non-HAP solvents can be recovered at high yields for reuse in subsequent batches. For the cast-cure work, we are developing new formulations that eliminate the use of the toxic isophorone diisocyanate (IPDI) crosslinker. Polyisocyanate materials are available that perform crosslinking reactions as effectively as IPDI with much less inhalation toxicity due to vastly decreased vapor pressures of the polyisocyanate material. Moreover, we are additionally developing processes that enable cast-cure formulations to be mixed in-item of complex geometry munitions to eliminate transfer of the energetic material to the item, thus eliminating the wastes associated with the mixing vessel.
“Mix-In-Case Green Processing with RAM” by Dr. Andrew Nelson
The effective processing of highly-filled composite materials can be a challenging task. Conventional mixers and vacuum casting techniques impose limitations on the amount of solid fillers as well as the liquid binder ingredients available to the material formulator. In many cases, the performance and insensitivity of high-energy composites can be enhanced by increasing to the solid particle loading within the composite and increasing the particle surface area. However, in current state-of-the-art high-energy composites formulations, these changes increase material viscosity and quickly eliminate conventional bladed mixing techniques to produce novel materials. RAM offers the ability to overcome these limitations of conventional mixers. This presentation describes the advantages of RAM over legacy processing techniques for preparing novel high-energy composite formulations. Process-related lessons learned and the safety steps implemented to prepare novel, high-energy composite materials will be described. In addition, we will discuss the advantages of in-case mixing and casting, and the ability to process multiple end items in a single mixing step.
Dr. Andrew Nelson is a senior research chemist at the Naval Air Warfare Center Weapons Division, China Lake, California. Andrew has worked as the principal investigator of a variety of basic, applied and demonstration research projects focused on the development and demonstration of new rocket propellant and explosive technology. Recently he has worked with the RAM technology to produce novel high energy propellants and PBX formulations. His current RAM related research projects are focused on the demonstration of mix-in-case, and continuous RAM operations to increase production rates and reduce the accumulation of hazardous waste associated with standard batch mixers. He has authored more than 30 peer-reviewed and International Traffic in Arms Regulations (ITAR)-restricted research papers and patents, including several on resonant acoustic mixing of high energy materials. He earned a bachelor's degree in chemistry from Bethany College in 1998 and he holds a doctoral degree in organic chemistry from The University of Nebraska-Lincoln (2004). Prior to joining the Department of Defense at Naval Air Warfare Center Weapons Division - China Lake, he was a Petroleum Research Fund (PRF) Alternative Energy Fellow at Northwestern University (2005 to 2007).
Dr. Eric Beckel is a Research Chemical Engineer at the United States Army Armament Research, Development, and Engineering Center (US Army ARDEC) located at Picatinny Arsenal, New Jersey. Eric’s current primary assignment is to research novel energetics for improved explosive and insensitive munition performance, and energetic processing techniques for improved environmental impact. To research and design new explosive formulations, Eric utilizes the RAM technology to allow for the generation of higher solids loadings materials that could not otherwise be processed using legacy equipment. Prior to working at the US Army ARDEC, Eric completed a two-year post-doctoral assignment at the Air Force Research Laboratory in Dayton, Ohio, in which he researched polymeric electro-optical devices for light modulation applications. Eric received his bachelor’s degree in chemical engineering from the University of Washington in 1998 and a doctoral degree in chemical engineering from the University of Colorado in 2005 with a specialty in polymeric systems.