Simulation On Properties Of Nitrate Ester Based Solid Propellants

The density functional theory(DFT)was used to study theoretically the binding energy when combine with H+,the wiberg bond indexes(WBI),the nucleus-independent chemical shift(NICS),affinity energy and gap energy of 19 different stabilizers in solid propellants.The strength of the nucleophilic capacity,the stability,the aromaticity and the ability to attract electrons were compared.The propertied and compatibility 6 different components in solid propellants were studied by molecular dynamic simulation.By using the molecular dynamic simulation,the binding energy,cohesion energy density,solubility parameter and Flory-Huggins interaction parameter were obtained.The compatibility of constituents was predicted by comparing the discrepancy of solubility parameters and Flory-Huggins interaction parameter.The origin of molecular interaction between the constituents was probed by analyzing the binding energy.Finally we studied the glass transition temperatures on pue HTPB,ATPB and GAPA,and their double mixtures with other propellant components,and then we compared with the glass transition temperature obtained in the experiment.This paper included the following three sections:1.The structure of stabilizers were inverstigated by using the density function theory(DFT)method at the B3LYP/6-311G**level.We chose 19 solid propellant stabilizer,including AK2,M1-M5,STAB-1,new(2-ndpa),diphenylamine(DPA),dimethyldiphenyl urea(C2),diethyl diphenyl urea(EC),dibenzoyl urea(DPA),N-(2-methoxyethyl)p-nitroaniline(MENA)and so on.We compared the strength of nucleophilic capacity,by calculating the binding energy when combine with H+.The stabilization effect decreases with the increase of dissociation energy.The correlation between WBI and NICS measured for the stabilization effect shows stability.2.The propertied and compatibility of 1,2,4-butanetriol trinitrate(BTTN),nitroglycerine(NG),cyclotetramethylenete-tranitramine(HMX),hydroxyl-terminated polybutadiene(HTPB),dioctyl sebacate(DOS)and ethyl centralite(EC)were studied by molecular dynamic simulation.By using the COMPASS force field,the binding energy,cohesion energy density,solubility parameter and Flory-Huggins interaction parameter were obtained.The compatibility of constituents was predicted by comparing the discrepancy of solubility parameters and Flory-Huggins interaction parameter.The origin of molecular interaction between the constituents was probed by analyzing the binding energy.3.The glass transition temperature of the propellant was calculated by molecular dynamics simulation.Some of the components of the solid propellant were hydroxyl-terminated polybutadiene(HTPB),azido-terminated polybutadiene(ATPB)and glycidyl azide polymer azide(GAPA).The glass transition temperature was obtained by plotting the specific volume of the material at different temperatures.After the comparison with the experimental data,the problems in the calculation were found and the improvement measures were provided.And then,we calculated the glass transition temperatures of HTPB,ATPB and different plasticizers such as 1,2,4-butanetriol trinitrate(BTTN)and nitroglycerin(NG),to compare the effect of adding different plasticizers is good or bad.