| Microporous propellant has extremely important application value in the field of propellant charge due to its excellent increasing burning rate.In order to explore the extrusion processing technology of microporous propellant,cellulose acetate（CA）was used as a substitute for nitrocellulose（NC）and supercritical CO2（Sc CO2）micro-foaming extrusion method was used to prepare microporous propellant substitute.Under different process conditions,a slit rheometer was used to study the rheological properties during the extrusion process,and the micropore morphology was observed with a scanning electron microscope（SEM）.Finally,the impact strength of the product were tested by a drop-weight impact tester.And summarized the relevant laws,analyzed the reasons,Meanwhile,related laws were summarized and the reasons were analyzed,which laid the experimental foundation for further research.The experimental results show that during the extrusion foaming process,as the barrel temperature increases from 40℃to 50℃,the apparent viscosity of the sample decreases,and the pressure drop rate first increases from 0.09MPa/s to 0.12MPa/s（45℃）,then dropped to 0.10 MPa/s.The volume flow rate increases with the barrel temperature from 0.18cm3/s to 0.22cm3/s,but the rate of increase gradually slows down.The increase in CO2 injection volume has obvious plasticizing effect,the increase in pressure drop rate reaches 36.36%,and the increase in volume flow rate reaches 63.16%.Increasing the solvent ratio increases the volume flow rate from 0.16cm3/s to 0.29cm3/s,which has an increase up to 81.25%.The increase of the screw speed also allows the sample to obtain better fluidity,and the increase in pressure drop rate and volume flow rate are 55.56%and 66.67%,respectively.Research on the morphology of the micropores shows that as the temperature of the barrel increases,the cell size increases from 2.310μm to 16.277μm,the cell density decreases by two orders of magnitude,and the porosity increases sharply from 7.808%to 27.329%.As the solvent ratio increases,the cell size increases from 2.645μm to 10.477μm,the porosity increases from 2.928%to 18.634%,and the cell density decreases from 12.437×109/cm3 to1.855×109/cm3.When the CO2 injection rate was increased from 0.18m L/min to 0.22m L/min,the cell size decreased by 4.764μm,and the cell density increased by 30.597×109/cm3.With the screw speed increased from 8r/min to 14r/min,the cell size decreased by 1.286μm,and the cell density increased by 7.630×109/cm3.The increase in die temperature makes the porosity increase from 3.372%to 14.020%and the cell size increase from 1.716μm to8.595μm,while the cell density decreases from 39.491×109/cm3 to 4.403×109/cm3,but the temperature was too high.Low will affect product quality.But the temperature is too low will destroy the quality of the product.Through the analysis of the impact strength of the microporous sample,it is found that the smaller cell size and cell micropore density are beneficial to improve the mechanical properties of the sample.Therefore,both increasing the screw speed and the amount of CO2injection can improve the impact strength of the product,and the impact strength of the sample has been increased by 11.37KJ/m2 and 12.35KJ/m2,respectively. |
