Preparation Of Ferrocene Nitrile Oxides And Their Click Immobilisation In HTPB And Self-healing Polyurethane

Ferrocene-based derivatives are commonly used as burn rate catalysts(BRCs)for solid propellants.However,the low catalytic efficiency and unsafe problems caused by the ease of migration,volatility and lack of all-round dispersion of ferrocene-based BRCs in solid propellant use,as well as the superposition of unsafe deterioration due to external load-induced damage,are disadvantages that have somewhat hindered the application of ferrocene-based BRCs in the field of solid propellants.Therefore,this thesis introduces nitrile oxides into the ferrocene structure to synthesise ferrocene nitrile oxides,which are directionally immobilised in a lattice of terminal hydroxyl polybutadiene(HTPB)and uniformly distributed in a selfhealing polyurethane encapsulated with ammonium perchlorate(AP)via a click reaction;thus achieving an integrated design of a combustion rate catalyst-binder and propellant microinterface damage resistance and external damage micro-interface self-healing of interfacially encapsulated AP.Specifically,the work in this thesis includes the following aspects:(1)the introduction of nitrile oxides into the small molecule ferrocene structure,and the characterisation of its structure and properties.The results show that the thermal decomposition temperature of AP is 293°C when 8% mass fraction of ferrocene nitrile oxide is added,which is 155°C earlier compared to pure AP.The weight loss of ferrocene nitrile oxide was 0.09% at 70 °C.The ferrocene nitrile oxide was also applied to HTPB to investigate the effect of ferrocene nitrile oxide on the mechanical and thermal properties of HTPB propellant and the migration resistance of ferrocene nitrile oxide.The results showed that the tensile strength and elongation at break of ferrocene nitrile oxide added with a mass fraction of 0.8% at R=1.2 were(1.62±0.01)MPa and(198±22.35)% respectively,which increased the tensile strength by 230% and the elongation at break by 30%.The two stages of thermal decomposition of ferrocene nitrile oxide added to HTPB remained mainly 270-440°C and 440-500°C,with 30% and 70% weight loss respectively.The addition of 0.8% mass fraction ferrocene nitrile oxide resulted in 21 d migration of 0 cm and 50 d migration of 0.2 cm.(2)Double bonds were introduced into the self-healing polyurethane structure to investigate the thermal,mechanical and self-healing properties of the self-healing polyurethane.The results showed that the synthesized polyurethanes had excellent tensile strength(4.87±0.03)MPa,maximum elongation at break(591±2.78)% and good self-healing properties(100%repair rate at 50°C for 3 h)and encapsulated AP properties(water absorption of 0.13% and impact resistance of 6 J).Self-repairing polyurethanes containing ferrocene were prepared to investigate the effect of the content of ferrocene nitrile oxide on the performance of the selfrepairing polyurethanes.The structure and properties were characterised and the results showed that the introduction of ferrocene groups into the self-repairing polyurethane resulted in a decrease in self-repairing properties,an increase in the time to 100% repair rate from 3 h to 5 h,and an encapsulation of AP properties(water absorption 0.49% and impact resistance1 J).The two stages of thermal decomposition remained mainly 200 to 335°C and 335 to435°C with a weight loss of 38% and 62% respectively.