Energetic thermoplastic elastomers as binders in solid propellants
Publish date: 2003-01-01
Report number: FOI-R--0866--SE
Written in: English
ADN is a very desirable oxidiser with respect to energy and environmental aspects, but it is also known to decompose in the presence of common binder ingredients. In order to develop alternative binders, different thermoplastic elastomers have been synthesised. Successful attempts were made to produce copolymers of polyNIMMO with poly(ethylene-co-1,2-butylene)diol and pentanediol respectively. The cured materials had glass transition temperatures between -11°C to -16°C. The plates made of polyNIMMO-poly(ethylene-co-1,2- butylene)diol also had a melting peak between 50°C - 80°C. The Tg for the co-polymers is too high to match the service temperature requirements of -40°C to +60°C. Also, the mixtures solidify when removed from the heat source, making them difficult to work with. Since these copolymers are too difficult to melt process at temperatures below 90°C, they are for the moment not suitable for ADN-based propellants. A series of polyNIMMO-polyTMPO block-copolymers were made and also melt blends of polyNIMMO and polyTMPO were formed. The polyNIMMO-content in the copolymers was not more than 20mol% and the energy content compared to pure polyNIMMO was low. The copolymers showed to have acceptable elastic properties in the service temperature interval, while blends did not. However, small, exothermal phase transitions were discovered in the copolymers in the temperature interval of -15 - +5ºC, which could cause problems in ADN-matrix applications. A GAPpolyTMPO-copolymerization was also performed, but it was not successful.