Synthesis Of BAMO-GAP Based ETPE And Its Application In Gun Propellants

For the research and application of energetic thermoplastic elastomer (ETPE), the molecular structure and synthesis of BAMO-GAP based ETPE have been designed and studied. Based on the ETPE’s mechanical properties as evaluated standard, BAMO-GAP based ETPE’s synthesis process and materials distribution ratio have been studied, and its structure and properties also have been characterized; using BAMO-GAP based ETPE as the binder, its(the ETPE) application in the propellants has been carried out, and a comparative study has also been carried out with the GAP-MDI based ETPE and BAMO-AMMO based ETPE; using the dispersion D method, the dispertion of solid particles in the ETPE propellant(high solids content) has been evaluated, and based on the ETPE propellant’s mechanical properties and combustion properties as evaluated standard, the evaluated method of dispersion’s reliability has been analysed comparatively. The main findings are as follows:The ETPE’s soft segment has been designed to be glycidyl azide polymer (GAP), and its hard segments have been designed to be poly(3,3’-bis(azidomethyl) oxyetane)(PBAMO), 4,4’-diphenylmethane diisocyanate(MDI), and 1,4-butanediol (BDO, as a chain extender), and its synthesized method was prepolymerization. The BAMO-GAP based ETPE’s synthesized process conditions have been confirmed to be:using THF as solvent, prepolymerization temperature was 80 ℃, prepolymerizati-on time was 1.5h, mass fraction of catalyst was 0.9%, curing condition was storage at 60 ℃ for three days. And the material ratio was:isocyanate index (R) was 1.01, hard segment content (Y) was 50%, chain extender ratio (V) was 1:4:3. The ETPE sample has got the polyurethane structure and energetic group, which meant the expected product has been synthesized. The product’s tensile strength (σ) was 6.75MPa, glass transition temperature (Tg) was about -20℃,elongation at break (ε) was 1024.74%, softening point temperature (Ts) was 76℃, explosion heat (Qe) was 1221.3J·g-1 and combustion heat(Qc) was 22570.6 J·g-1.From the point of view of propellants’ preparation quality, BAMO-GAP based ETPE propellant was best; GAP-MDI based ETPE propellant was soft and its surface was a little rough; BAMO-AMMO based ETPE propellant’s volume swelled so that the density was reduced. From the actual performance, three propellants’combustion curves were smooth and their combustion properties were good; but their burning rate pressure exponents were large, which meant all propellants had greater space to be modified. BAMO-AMMO based ETPE propellant’s apparent burning rate rised high.GAP-MDI based ETPE’s brightness threshold ranged from 112 to 117, and BAMO-AMMO based ETPE’s brightness threshold ranged from 154 to 160; the samples’ spacing of parallel intervals were the same as their RDX particles’ size; the bightness of samples’ microscopic images hasn’t got effects on the dispersity evaluated results. The samples’ dispersitions from good to bad were:FNE-21, FNE-22, FNE-24, FNE-19, and FNE-23, FNE-17; mechanical strengthes from good to bad were FNE-21, FNE-22, FNE-24; combustion stabilities from good to bad were FNE-21, FNE-22, FNE-24, FNE-19, and FNE-23, FNE-17. The mechanical quality and the combustion properties’ quality were consistent with the dispersity evaluated results. So that dispersity evaluated results were accurate.