Study On The Optimal Synthesis And Curing Of Difluoroamino Energetic Binder

Difluoroamino can decompose to produce a kind of gas with relatively low molecular weight and high heat,and fluorine has oxidizability,which can not only improve the oxygen balance of adhesive system,but also easily react with metal fuel components(such as aluminum or boron)in propellant to release heat,so it has special high-energy performance.As a new kind of energetic binder,it has an important application value in improving the energy of solid propellant.In traditional composite solid propellants,binder prepolymer is usually crosslinked with curing agent to form a three-dimensional network structure,which is used as the binding matrix of oxidant,metal fuel and other additives.Therefore,in this paper,3-difluoroaminom ethyl-3-methyloxyheterocy cl obutane(DFAMO)and 3,3-bisazidomethoxyheterocyclobutane(BAMO)were used as monomers to obtain different molecular weight copolymerized product adhesives(PDB)through cationic polymerization,and then isocyanate and non isocyanate curing were studied.The main work is as follows:DFAMO and BAMO were used as monomers to obtain the corresponding difluoroamino binder by cationic ring opening polymerization.PDB with different molecular weight was obtained by controlling the input ratio of solvent and monomer.When the amount of two chloroethane in the solvent was 4,5,6,6.5 and 7 times of the total mass of DFAMO and BAMO,the molecular weight of the obtained PDB was 6864 g·mol-1,5921 g·mol-1,4315 g·mol-1,3788 g·mol-1 and 3413 g·mol-1.Then the structure of the product was characterized by NMR and FT-IR.The typical aliphatic isocyanate curing agents,isophorone diisocyanate(IPDI)and biuret polyisocyanate(N-100),were used to cure PDB.The structure of PDB/IPDI and PDB/N-100 curing systems were analyzed by FT-IR and NMR,respectively.The results showed that there was no carbamate group in PDB/IPDI system,and N-100 destroyed the difluoroamino structure of PDB.Then,PDB/IPDI and PDB/N-100 curing system were simulated by using Materials Studio 6.0 software.The results showed that PDB and IPDI had no effective groups,while N-100 system was more inclined to react with difluoroamino group on PDB.The calculated results are consistent with the experimental results.Neither IPDI nor N-100 can be used for curing PDB.The typical curing agents TDI,NDI and MDI were used to cure PDB.The structure of PDB/TDI,PDB/MDI and PDB/NDI curing systems were analyzed by FT-IR and NMR.The results show that TDI,MDI and NDI can react with PDB and do not destroy the difluoroamino group in PDB chain.Then,the PDB/TDI curing system was simulated by molecular dynamics.The calculated results are consistent with the actual experimental results,so the three curing agents are suitable for the curing of PDB.Finally,the curing reaction kinetics of PDB/TDI was studied by DSC.The curing reaction kinetic parameters of PDB/TDI were obtained from Kissinger equation and crane equation.The structure of PDB/TPTM curing system was analyzed by FT-IR.The results show that PDB can react with TPTM in 1,3-dipolar cycloaddition at 60?,and the curing product of triazole cross-linking system is formed.The curing kinetic equation of PDB/TPTM system was obtained by DSC.