New High-energy Propellant Surface Treatment Technology Research

To improve the initial burning gas generating regulation and application properties of azidonitramine propellant (DA-propellant), a novel surface modification method was proposed in this paper based on the 1,3-dipolar cycloaddition reaction. A multiple acetylene-terminated compound was introduced as the deterrent precursor, it reacted with azidonitramine monomer to form polytriazole network, so that for one aspect the initial burning gas generating rate reduced and the effect of progressive burning was fulfilled, and the other aspect the long-storage stability of the deterred propellant was assured.Tripropargyl 1,3,5-benzenetricarboxylate (TPBC) was prepared by two steps with the raw materials of 1,3,5-benzenetricarboxyl acid and propargyl alcohol, and its purity and structure was characterized by HPLC, FTIR and 1H-NMR. TPBC was used as a deterrent, and the other two deterrents DBP (dibutyl phthalate) and PPA (poly(1,2-propylene glycol adipate)) were used as the comparative ones, DA-propellant was modified by rotating-drum technique to investigate their combustion property and long-storage stability. The results showed, the combustion property of DA-propellant deterred by DBP changed a lot after stored for 3 months under room temperature, and the deterrent of DA-propellant deterred by PPA migrated obviously after stored for 3 months under 50℃, so DBP and PPA could not be used as the deterrent for DA-propellant. For DA-propellant deterred by TPBC, the initial burning activity reduced from 6.3(MPa·s)-1 of undeterred DA-propellant to 3.3(MPa·s)-1,indicating that the initial burning gas generating rate was reduced obviously; the relative pressure Bm at the maximum burning activity was 0.498, the burning progressivity index Pi was 0.128 (Pi of undeterred DA-propellant was -0.176), demonstrating the effect of obvious progressive burning; the initial burning activity changed little after stored for 3 months under room temperature and 50℃, and the burning activity reduced a little just during the middle and late burning process, showing excellent long-storage stability.Acetylene-terminated triethylolamine (ATTEA) was synthesized successfully from raw material triethylolamine, bridge agent IPDI and capping agent propargyl alcohol. ATTEA was used as the deterrent, DA-propellant was modified by rotating-drum technique, the investigation results indicated:ATTEA showed good effect of deterring for DA-propellant, its initial burning activity was just about 1.5(MPa·s)-1; DA-propellant deterred by ATTEA had excellent effect of progressive burning, its relative pressure Bm at the maximum burning activity was 0.406, and its burning progressivity index Pi was 0.754; Heat accelerated aging test also demonstrated excellent long-storage stability of DA-propellant deterred by ATTEA.The results in this paper showed wide prospect of 1,3-dipolar cycloaddition reaction applied in the surface modification technique of azidonitramine propellant, and this approach was worthy of further investigation.