| Composite solid propellants are high-energy mixtures which could produce a large driving force when burned.And it has been widely applied in the Aerospace area due to its high energy,low characteristic signal,excellent low-temperature mechanical properties and safe storage performance.In general,the composite solid propellant adhesive was cured due to the reaction between the terminal hydroxyl of the resin used and polyisocyanate.However,this curing system was very sensitive to humid conditions,the development and production of propellants are severely constrained by the season and environment.Some new solid fillers with high-energy,low-signal,such as nitroformamidine,ammonium dinitramide(ADN)and boron powder,are poorly compatible and have poor mechanical properties when combined with a hydroxyl-terminated binder/isocyanate curing system to prepare a composite solid propellant.Solid propellants with high-energy and low-characteristic signals are the targets that have been pursuing.So the high-energy azide propellant has aroused much attention among scholars both at home and abroad.The azide group increases the energy density of the binder and the polarity of the curing system,as a result,the problem of compatibility between binder and solid fillers is improved to a certain extent.Based on the principle of click chemistry,this article investigates the terminal alkynyl resin and azido curing agent binder system to solve the above problems.The main work carried out in this thesis is as follows:The kinetics of the reaction of bis-azido compounds(BPDBA)with methyl butynol was investigated by using nuclear magnetic methods.Reaction rates under non-catalytic and CuI conditions were studied respectively,and the optimal reaction conditions of the terminal alkynyl and azide compounds were explored to determine the process conditions of the terminal alkynyl resin and azido curing agent binder system.The results showed that the reaction of azide with alkyne was a secondary reaction.Taking all into consideration,the curing condition of polytriazole adhesive was determined,which was at 60 oC for 7 days and without catalyst.Polyether/polyester with terminal alkynyl groups,bis-alkynyl chain extender(BEBA),tri-alkynyl crosslinking agent(TMPTPE)and bis-azide curing agent(BPDBA)were synthesized to prepare a series of polytriazole elastomers.The effects of factors including curing parameters(Rt),hard segment content(H%),and crosslinking agentcontent(C%)on the mechanical properties of cured films were investigated.And the crosslinking network of polytriazole elastomer was evaluated by swelling experiment.The compatibility and mechanical properties of polytriazole adhesive with plasticizer were also studied.The results showed that the tensile strength of the polytriazole adhesive and the elongation at break were changed from 0.71 MPa to 5.72 MPa,300%to 720%,respectively.The polytriazole cross-linked network structure was able to be well controlled by the loading of crosslinking agent.Moreover,the strong polar plasticizer was compatible with polytriazole adhesive and formed a high plasticizer elastomer.Polyurethane elastomers were prepared from Polyethylene adipate diethylene glycol(PADG),bisphenol A,trimethylolpropane(TMP)and MDI.A series of polyurethane samples were prepared at the same equation parameters that of the polytriazole curing system(azide and alkyne groups),which were compared with the polytriazole samples at the mechanical and thermal properties.And effect of water on polyurethane and polytriazole adhesives curing system was explored.The experimental results showed that water had no effect on polytriazole adhesive curing system.Polytriazole elastomer had better mechanical properties and heat resistance than polyurethane elastomer.The higher carbon content the polytriazole elastomer had increased the energy of the adhesive to a certain degree.Therefore,polytriazole adhesive curing system is expected to become a new type of composite solid propellant curing system. |
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