| Ferrocene compounds are mainly used in HTPB/AP composite propellant due to their excellent performances in modifying burning-rate (BR) of the propellants. At present, there are a large variety of commercialized ferrocene-based burning rate catalysts including n-butyl ferrocene (NBF), t-butylferrocene (TBF),2,2-(ethyl ferrocene)propane (Catocene), n-octyl ferrocene and bis(ethylferrocenyl)methane (Hycat 6D)). Although these ferrocenes can enhance burning rate of the composite propellants, they still have some drawbacks such as easy to migrate and volatile. Thus, researching for a kind of excellent ferrocene burning rate catalysts, which have the ideal combination of various aspects including excellent catalytic performances, high thermal stability, high electrochemical stability and low mobility, becomes the primary goal at this stage for all researchers.Ionic compounds were paid much attention by the researchers in the field of ferrocene-based burning rate catalysts, owing to the unique physicochemical properties of ionic compounds (higher density, lower vapor pressure, easier modification of both cations and anions). The researchers try to combine molecule of ionic compounds and ferrocene derivatives and design nitrogen-rich ferrocenyl ionic compounds with good thermal stability, low sensitivity and easier to reach balance during combustion.This thesis introduced polycyano anions into ferrocenyl ionic compounds, designed and synthesized a kind of dinuclear ferrocenyl imidazilium ionic compounds, aiming to lowering the migration tendency of the BR catalysts and meanwhile improving energy level of the propellants. The main contents of the thesis are as follows:(1) Using dinuclear ferrocenylalkylimidazilium iodides with different alkylene chains (n= 1,4-10), potassium 1,1,3,3-tetracyanopropenide, pyridinium 1,1,2,3,3-pentacyanopropenide, tetrethylammonium 1,1,2,5,6,6-hexa-cyano-3,4-diazahexadienide as raw materials, the thesis designed and synthesized 24 dinuclear ferrocenylimidazolium ionic compounds, with general molecular formula being [FcCH2(IM)(CH2)n(IM)CH2Fc]2+(X-)2[Fc=ferrocene; IM=imidazole; n=1,4-10; X-= 1,1,3,3-Tetracyanopropenide (compounds 1-8); X-= 1,1,2,3,3-Pentacyano- propenide (compound 9-16) and X-= 1,1,2,5,6,6-hexacyano-3,4-diazahexadienide (compounds 17-24). Environment friendly solvent water, together with little amount of methanol, was used in the synthetic procedures for the new compounds. The synthesis of the new compounds is simple and the products were easily purified with high yields. The new compounds were characterized by’H NMR and 13C NMR, EA, FT-IR, UV/Vis techniques. Additionally, the molecular structure of a compound was confirmed by single-crystal X-ray diffraction.(2) The electrochemical properties of the new compounds 1-24 were studied by cyclic voltammetry (CV). The results found that Ep1/2 of the compounds is in the range of 553-673 mV, higher by about 200 mV than those of NBF (394 mV), TBF (378 mV) and Catocene (347 mV), suggesting that the new compounds have better antioxidant capacity than the neutral ferrocene compounds.(3) The migration tendency of some compounds (2,4,7,10,18) and Catocene (Cat) was investigated. It is found that the migration percentage of Catocene was about 38.14% after 30 days aging, but those of 10 and 18 are 0.04% and 0.17%, respectively. Meanwhile, the migration percentages of 2,4,7 were 0% (not detected). Therefore, the high migration tendency of the neutral ferrocene derivatives was overcome by the characteristic properties of the ferrocenyl ionic compounds.(4) By DSC technique the combustion catalytic properties of the compound 1-24 and Cat on thermal decomposition of main components of solid propellants, ammonium perchlorate (AP) and 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), were evaluated. The results show that, when the optimal weight percentage (5 wt%) of a compound was added in AP, the phase transformation temperature peaked at 429.3℃ has no shift, but the peaks of both LDT and HDT stages of AP shifted significantly towards left, with the temperature peaks appeared in the range of 335.0-345.0℃, lower by 93.3-103.3℃ than the peak of the HTD stage of AP. The released heats of the mix systems are-875.1J·g-1 to-1611.1 J·g-1. When in RDX the new compounds were added in 5wt%, the released heats are between -831.SJ·g-1 and-1533.5J·g-1. Accordingly, the compounds 1-24 exert significant effects on thermal degradation of both AP and RDX.In summary, the 24 dinuclear ferrocenyl imidazilium ionic compounds reported in this thesis have significant catalytic effects on the thermal decomposition of main components of the solid propellants. They also have low mobility, high heat stability and strong antioxidant capacity. They have potential applications in composite solid propellants. |
PDF Full Text Request