Study The Effect On Two Additives The Properties Of NC-Based Propellant

In order to improve the mechanical properties of NC-based propellants containing RDX and NQ,NC-based propellants containing diglycerol tetraminitrate（DGTN）and thermoplastic polyurethane elastomer（TPU）were prepared by semi-solvent method.The effect of concentration of DGTN,concentration of TPU on the mechanical properties,thermal stability and safety properties of NC-based propellants were analyzed and discussed.The static mechanical properties（compression resistance and impact resistance）of propellant samples were tested by universal material testing machine and simply supported beam impact testing machine,and the effects of two additives on the propellant pharmacological properties were studied.The mechanical properties of NC-based propellants containing DGTN are less affected by temperature.Increase the content of DGTN in propellant,the density of propellant samples increases,the compressive strength decreases and the compression strain increases,but the impact strength increases.Temperature has a great influence on the mechanical properties of NC-based propellants containing TPU,especially the impact strength.With the concentration of TPU in NC-based propellants increases,the compressive strength of NC-based propellants decreases,the impact strength increases,and the compression strain gradually increases,and the low content of TPU has a great effect on the growth rate of compression strain.The thermal stability of propellant samples was tested by vacuum stability test.The results show that the gas release of the propellant samples per-unit mass is less than 2m L,and the thermal stability is qualified.The thermal decomposition process,thermal decomposition peak and thermal weight loss process of propellant were measured by differential scanning calorimetry（DSC）and thermogravimetry（TG）.The change of DGTN content has little effect on the T_P0of propellant.The thermal decomposition of NC-based propellants containing TPU can be divided into two stages.The first stage is at temperature range of 175℃-215℃,and the second temperature stage is about 215℃-260℃.With the concentration of TPU increases,the second decomposition stage becomes more obviously,and the T_P0of propellant gradually increases and the thermal stability of propellant is improved.The mechanical sensitivity（including impact sensitivity and friction sensitivity）,electrostatic spark sensitivity and thermal sensitivity of the propellant sample were used to characterize the safety performance of the propellant sample.The mechanical sensitivity,electrostatic spark sensitivity and thermal sensitivity of NC-based propellant containing DGTN are lower than those of triple-based propellant,and the safety of NC-based propellant is better than that of triple-based propellant.The explosive percentage of electrostatic spark sensitivity of NC-based propellant samples is zero.The insensitive to electrostatic spark stimulation shows that the electrostatic accumulation.In the range of 3%-9%DGTN content,with the increase of DGTN content,NC-based propellants become insensitive to impact and friction stimuli,and have little influence on the sensitivity of thermal stimuli.With the increase of TPU content,the mechanical sensitivity of NC-based propellant containing TPU has no obvious change rule,and becomes insensitive to thermal stimulation.