DEVELOPMENT OF A NEW GENERATION OF INSENSITIVE EXPLOSIVES AND GUN PROPELLANTS

For the last few decades, DRDC Valcartier has been involved in the synthesis of energetic thermoplastic elastomers (ETPEs) based on linear glycidyl azide polymer (GAP). A new generation of energetic polyester homopolymers was also developed at DRDC Valcartier, and their polymerizations yielded energetic thermoplastic elastomers containing ester groups that could be degraded. Some ETPEs were also synthesized based on polynitratomethylmethyl-oxetane (PolyNIMMO) and polyglycidyl nitrate (Polyglyn). These energetic homopolymers were used as macromonomers and were reacted with 4,4'− methylenebis (phenylisocyanate) to yield copolyurethane thermoplastic elastomers. These ETPEs are physically cross-linked rubbery materials that can be dissolved, recycled, and then be utilized to provide the basis for a new generation of insensitive explosives and high-energy low-vulnerability ammunition (HELOVA) gun propellants. The mechanical properties of these ETPEs were adjusted so that these compounds could be used as binders in propellant and explosive formulations demonstrating an insensitive character. First, the ETPEs were introduced into gun propellant formulations to yield HELOVA gun propellants. The latest developments yielded green HELOVA gun propellants with improved energy. Moreover, an insensitive explosive named XRT for "experimental rubbery TNT" was developed and led directly to the development of a new insensitive recyclable green explosive. Furthermore, our understanding of the environmental impacts of explosives during live-fire training led us to the development of concepts for a green weapon that will contain both green explosives and gun propellants. A major project named RIGHTTRAC for "revolutionary insensitive green and healthier training technology with reduced adverse contamination" was initiated in 2008 and will produce a green weapon based on these concepts. Because ETPEs are recyclable, they will allow for easier disposal and reuse of the new formulations at the end of their life cycle. This paper describes the syntheses of these ETPEs, the strategies that yielded the HELOVA gun propellants, the XRT and green explosives, the results describing their properties and insensitive characters, and the RIGHTTRAC project, which includes the concept and incorporation of green explosives and gun propellants.