Design,Synthesis And Performance Of New Neutral Polymeric Bonding Agents

Nitrate-plasticized polyether(NEPE)propellant has excellent energy density characteristics,which represented the developing direction of current high-energy solid rocket propellant.NEPE propellant was solidified via mixing nitrate(HMX or RDX),ammonium perchlorate(AP)particles and nitrate ester plasticized polyether polyurethane.In the propellant,the bond strength between oxidizer such as ammonium nitrate and ammonium perchlorate and the matrix of polyether polyurethane adhesive is weak,and the phenomenon of "dewetting" is easy to occur,which makes the mechanical properties of propellant fail to meet the requirements.The neutral polymer bonding agent(NPBA)invented by Kim C.S.has obviously improved the mechanical properties of NEPE propellant.With the update and development of NEPE propellant formula system and the improvement of solid rocket performance,the bond strength of traditional neutral polymer bonding agent gradually fails to meet the design requirements.In this paper,on the basis of the traditional neutral polymer bond,special bond functional groups such as amine group,Hein ring group and borate group were introduced to synthesize a variety of new neutral polymer bond,and the bond effect of the new bond was evaluated and studied.Firstly,the amine monomers were synthesized from methyl methacrylate and dimethylaminoethanol.Organic borate monomer was synthesized from n-butyl borate,propylene glycol and hydroxyethyl acrylate.Hydantoin,potassium hydroxide and 3-bromopropylene were used as raw materials to synthesize 3-allyl hydantoin.The three monomers were analyzed and characterized by infrared spectrometer,MRI,mass spectrometer and elemental analyzer.Secondly,acrylonitrile(AN)and hydroxyethyl acrylate(HEA)were used as comonomers to synthesize NPBA-1.NPBA-2 was synthesized using acrylonitrile,methyl acrylate(MA)and hydroxyethyl acrylate as comonomers.Using acrylonitrile,organic boric acid ester compound and hydroxyl acrylate as comonomers,the feeding ratio of organic boric acid ester compound was gradually increased to synthesize NNPBA-2-1,NNPBA-2-2 and NNPBA-2-3.;Using acrylonitrile,organic boric acid ester compound and hydroxyl acrylate as comonomers,the feeding ratio of organic boric acid ester compound was gradually increased to synthesize NNPBA-2-1,NNPBA-2-2 and NNPBA-2-3.Using acrylonitrile,3-allyl hydantoin and hydroxyl acrylate as commonomers,the feeding ratio of 3-allyl hydantoin was gradually increased to synthesize NNPBA-3-1,NNPBA-3-2 and NNPBA-3-3 as new bonding agents successively.Through titration and other tests,the optimal technological conditions for the synthesis of NPBA were determined.Finally,by measuring the Contact Angle and calculating the adhesion work,the interface adhesion properties of two traditional neutral polymer bond agents and nine new neutral polymer bonds with oxidants(RDX and AP)were studied.The results showed that: compared with the two traditional bond agents,the nine new bond agents had greater adhesion work with oxidants,indicating that the introduction of new bond functional groups into the traditional NPBA molecular chain enhanced the interface adhesion between bond agents and oxidants.The content of monomer containing new functional groups in the molecular chain of polymer bond agent has a certain influence on the interface bonding performance between bond agent and oxidant.In order to ensure the excellent bonding effect of new bond agent,the amount of monomer containing new functional groups is not easy to be too high.Among the 9 new types of bonding agents,NNPBA-3-1,NNPBA-3-2 and NNPBA-3-3,which contain hain ring group,have greater adhesion with oxidant,indicating that they have stronger interface bond with oxidant,and have better bonding effect in NEPE propellant containing RDX and AP.