The Effect Of Nitrated Bacterial Cellulose On Mechanics And Combustion Performance Of Propellant

In order to meet the requirements of ultra-long-range artillery and high-pressure armor-piercing projectiles,and to further improve the safety of the current artillery,it is necessary to develop high-energy propellants with excellent mechanical properties.In this paper,a kind of Nitrated Bacterial Cellulose(NBC)was used as the energy-enhancing material of the propellant.By adding 5%NBC to improve the mechanical properties of high-energy propellant,and further studied the influence of solvent ratio,solvent type and different plasticizer systems on the performance of NBC propellant.The morphology and structure of the propellant were characterized by SEM,XRD and FTIR.Its mechanical properties were tested through impact test,tensile test and compression test.The thermal decomposition performance was studied by thermogravimetric analysis and differential scanning calorimetry.The energy and combustion performance were analyzed through explosive heat test and closed explosive test.Research indicates:After adding NBC,the propellant matrix also presents a three-dimensional spatial network structure,and the mechanical properties of the nitramine propellant were greatly improved,and the impact strength at-40°C,20°C and 50°C was increased by 41.73%,141.18%and 156.04%,respectively,the compressive strength increased by 36.76%,30.28%and 48.68%,respectively,the tensile strength at-40°C also increased by 48.63%,and the tensile strength at 20°C and50°C remained unchanged.By adding 5%NBC,the energy of the nitramine propellant was increased by 0.74%,and the burning rate coefficient was increased by 4.16%,5.25%,4.52%at-40°C,20°C,and 50°C,respectively.The burning rate pressure index increased by 1.57%,1.02%,and 2.13%respectively.Because the solvent of ethyl alcohol ether has poor dissolving ability for NBC,when the solvent was used for kneading,the material was loose,and it was difficult to prepare qualified propellant.On the whole,the NBC nitroamine propellant sample used the ethanol-acetone mixed solvent(volume ratio is 2:1)in the kneading process had better mechanical properties than using the ethanol-ethyl acetate mixed solvent.Take the sample containing NG/DEGN propellant as an example,the impact strength,tensile strength,and compressive strength of samples using alcohol and ketone solvent at-40°C are 3.18%,5.53%,and 31.67%higher than those of alcohol ester solvent samples.When alcohol ester solvents are used,the burning rate coefficient of the propellant is larger,and the burning rate pressure index is greater than 1,the burning rate is greatly affected by pressure,which is not conducive to the smooth combustion of the propellant.The NBC nitramine propellant using DEGN as a plasticizer has high impact resistance(at-40°C,20°C and 50°C,reaching 16.71k J/m~2,46.42k J/m~2 and 57.00k J/m~2,respectively)and higher tensile and compressive strength.When NG was used as a plasticizer,its energy(1134.06J/g)was higher and burning rate was faster.At-40°C,20°C,50°C,compared NBC-NG nitramine propellant with the NBC-TMETN nitramine propellant,the burning rate coefficient of the amine propellant was increased by 2.17%,4.85%,and 4.26%,and the burning rate pressure index was increased by 5.65%,4.16%,and 8.27%.