Nitrate ester plasticized thermoplastic polyurethane elastomers propellant

A novel thermoplastic polyurethane elastomer based on co-polyether (ethyleneoxide-tetrahydrofunan) as soft segments, isophorone diisocyanate and 1,4-butanediol as hard segments was synthesized. It was used as propellant binder. In order to increase the miscibilities of thermoplastic polyurethane elastomers with nitrate ester, polyethyleneglycol was incorporated with co-polyether (ethyleneoxide-tetrahydrofunan) as soft segments. When the molecular weights and contents of polyethyleneglycol were controlled to 4000 and 6% of soft segments respectively, the properties of thermoplastic polyurethane elastomers were perfect. The plasticizing ratio that nitrate ester to thermoplastic polyurethane elastomers exceeded 4 and no crystallinities were determined under room temperature. The propellant sample was prepared by conventional absorption-rolling-extrusion process and the mechanical and combustion properties were evaluated. The maximum impulse reached up to 2 598 N · s/kg-2 648 N · s/kg and was a little higher than HTPB propellant. Measured results revealed that a promising TPE propellant candidates showed good processing temperature (< 393 K) and excellent mechanical properties. The burning rate pressure exponent reached as low as 0.36, which lends to a easy control in propellant combustion without the addition of burn rate catalysts.