Synthesis Of Methacrylic Acid Polyethylene Glycol Diester And Its Toughening Effect On Nitramine Propellant

This thesis consists of two parts: esterification modification of methacrylic acid and improvement of mechanical properties of propellant.By orthogonal experiment method,the better conditions for the esterification of polyethylene glycol-400 and methacrylate were obtained.Through the single factor experiment method,the better conditions for the esterification of polyethylene glycol-2000 and methacrylate were obtained.Using nitrosamine propellant tablets as raw materials,methacrylic acid polyethylene glycol diesters with molecular weights of 461 and 2240 were added as toughening agents,and the 1%,2%,3%mass fraction of the esterified product nitrosamine propellant was suppressed by the semi-solvent method respectively.The pendulum impact tester and the drop hammer impact tester were used to test the radial and axial impact strength of the propellant sample,and the toughening mechanism of the propellant sample by the addition of methacrylic acid polyethylene glycol diester was discussed.The main research contents of this article are as follows:(1)Taking polyethylene glycol-400 and methacrylic acid as the main raw materials,adopting the orthogonal experiment design method,the four influencing factors were investigated.According to the analysis of the orthogonal experiment results,the bettert conditions for the esterification reaction between methacrylic acid and polyethylene glycol-400 are that the acid-alcohol molar ratio is 2.5:1,the reaction temperature is 110?,the amount of catalyst is 1.5%,and the amount of polymerization inhibitor is 0.5%.The structures were characterized by fourier transform infrared spectroscopy(FT-IR)and nuclear magnetic resonance spectroscopy(NMR).DSC analysis results show that compared withpolyethylene glycol,the esterification product has no crystallization phenomenon and the material structure has changed.(2)With polyethylene glycol-2000 and methacrylic acid as the main raw materials,the single factor experimental design method was used to investigate the five influencing factors.According to the results of single factor experiment,the optimal conditions for the esterification of methacrylic acid and polyethylene glycol-2000 are as follows: the molar ratio of acid to alcohol is 3.0:1,the reaction temperature is 100 ?,the amount of catalyst is 1.5%,the amount of polymerization inhibitor is 1.0%,and the vacuum degree is 0.09 MPa.The structures were characterized by fourier transform infrared spectroscopy(FT-IR).DSC results show that the glass transition temperature and melting temperature of PEG-2000 diester are lower than those of PEG.(3)In this paper,1% ~ 3% mass fraction of toughening agent was added to the propellant samples with polyethylene glycol methacrylate as toughening agent,and the effect of different content of esterified materials on the related properties of the system was studied.The results showed that: with the increase of the amount of ester,the propellant density decreases slightly.The radial and axial impact resistance tests found that at low temperature(-40 ?),the propellant sample with 1% PEG-400 esterified product had the best radial and axial impact strength.While at normal temperature(20 ?),the propellant sample with 3% PEG-2000 esterified product had the best radial and axial impact strength.