Synthesis Of High Nitrogen Azole Ferrocene Burning Rate Catalyst And Study On Its Combustion Catalytic Performance

Burning rate catalysts(BRCs)are additives which can regulate burning rates of solid state propellants.They can increase burning rate and reduce the pressure index of a propellant,and also maintain combustion stability of the propellant.Ferrocene-based BRCs such as Catocene have wide applications in composite solid propellants.However,they show high migration and high volatility problems and crystallization at low temperature during prolonged storage of the propellants.These shortcomings will shorten service life of the propulsion systems and increase defense expenditures,and even fail to achieve the predesigned ballistic performance of the missiles.Therefore,it is of great significance to develop new types of ferrocene-based burning rate catalysts with low migration trends and high thermal stability as well as excellent catalytic properties.The previous studies found that ferrocenyl-functionalized amino compounds synthesized by click reaction exhibit almost no migration and has excellent catalytic effects on the thermal decomposition of AP,RDX and HMX.Based on the above advantages,twenty new nitrogen-rich ferrocenes were designed and synthesized.The main research work is as follows:(1)Using ferrocenylmethanol?1,1 '-ferrocenyldimethanol?3-bromopropyne and others as raw materials ferrocene derivatives with mono(imidazolyl,pyrazolyl and triazolyl-1H-1,2,3-triazolyl)groups(1-10)and bis(imidazolyl,pyrazolyl or triazolyl-1H-1,2,3-triazolyl)groups(11-20)were designed and synthesized.The structures of the new compounds were characterized by multiple techniques such as 1H NMR,13C NMR,FT-IR and UV/Vis.The crystal structures of six compounds(1,2,5,6,9 and 10)were additionally determined by single-crystal X-ray diffraction.(2)The thermal stability of they 20 new compounds was tested by TG technique.The results showed that compounds 11-20 have higher thermal stability than compounds 1-10 and Catocene.The volatility of the compounds was evaluated by TG at 70? for 24h.The results showed that the weight losses of the new compound were in the range of 0.14%?2.66%,which is significantly lower than the weight loss of Catocene(4.52%).(3)The electrochemical behavior of the compounds 1-20 were determined by cyclic voltammetry.It was found that the oxidation potentials of the new compounds were higher than those of the common commercial ferrocene-based BRCs under the same conditions,indicating that the new compounds have stronger antioxidant capacity.The electrochemical behavior of compounds 1-10 in different solvents(DMSO,CH2Cl2,CHCl3)was also studies.It was found that the peak shapes of their CV curves were dependent closely on polarity of the solvents.The greater the polarity of a solvent,the better the peak shape of its redox peak.It was found that the peak current value of compound 3 has linear relationship with the square root of the scan rate in DMSO.The results showed that the electrochemical behavior of compound 3 is controlled by the diffusion rate at room temperature and follows Fick's law.(4)Choose five compounds(3,4,9,16,20)as representatives to evaluate their migration tendency at 50? for four weeks,with ferrocene and Catocene as references at same conditions.It was found that the migration trends of the five compounds were not obvious after four weeks,meanwhile the migration distances of ferrocene and Catocene after four weeks were 2.4 cm and 1.3 cm,respectively.The results indicated that anti-migration abilities of the new compound are extremely better than those of ferrocene and Catocene.(5)DSC technique was used to evaluate catalytic properties of these new compounds on the thermal decomposition of AP,RDX and HMX.It was found that AP with compounds 1-20(5 wt.%)as additives can release heat ranged between 1101.10 J·g-1 and 1937.71 J·g-1,much higher than AP itself(746.53 J·g-1),and the temperature range of AP during exothermal decomposition is narrowed from 175.5? to less than 117.7?.The results indicated that the addition of compounds 1-20 in AP obviously increased the released heat and narrowed the temperature range of AP,and the high temperature decomposition peak significantly moved forward,indicating that 1-20 exhibit great effects on the thermal decomposition of AP.Similarly,the addition of compounds 1-20(5 wt.%)in RDX can increase the released heat of RDX from 692.93 J·g-1 to 1007.90 J·g-1?1935.28 J·g-1,showing that the new compounds can promote thermal disintegration of RDX.The mixtures of 2,4,7,10 or one of 11-20(1 wt.%)with HMX(99 wt.%)can release heats in the range of 1057.34 J·g-1?1267.45 J·g-1,a little higher than that of HMX itself(1052.74 J·g-1),whilst the addition of other new compounds in HMX can reduce the released heat of HMX,these results showed that the new compounds exert weak effect on the thermal decomposition of HMX.In addition,it was found that the catalytic effects of compounds 11-20 were better,in the whole,than compounds 1-10 on the thermal degradation of AP,RDX and HMX,indicating that high nitrogen content in the new compounds was favorable for improving their combustion catalytic abilities.(6)The thermal behaviors of RDX and HMX catalyzed by four compounds 1,6,15 and 16 were studied under non-isothermal conditions by DSC.The results showed that compounds 1,6 and 16 as additives can reduce activation energy of RDX by 37.10 kJ·mol-1,96.45 kJ·mol-1 and 37.75 kJ·mol-1,respectively.Compounds 6 and 15 can reduce activation energy of HMX by 50.14 kJ·mol-1 and 103.74 kJ·mol-1,respectively.The related thermal decomposition kinetic parameters and mechanism functions were also obtained.