Rheological Property And Mechanical Property Of Energetic Material Substitute In Extrusion Process

In order to improve the quality of energetic materials in extrusion process,the cellulose acetate(CA)has been used as energetic materials substitute in single-screw extrusion process,while the supercritical carbon dioxide(SC-CO₂)acts as the plasticizer.The rheological properties of the CA and CA/SC-CO₂ solutions were measured by the slit die rheometer in extrusion process.The mechanical properties of the CA products in extrusion assisted with SC-CO₂ were studied by impact strength tester.In this paper,the research results provide some theoretical basis in safety,product quality and application of energetic materials in extrusion processing.The results show that both of the CA and CA/SC-CO₂ solutions are non-Newtonian pseudoplastic fluids during the screw extrusion process,with the presence of SC-CO₂,the shear viscosity,die pressure and viscosity coefficient of the CA solution decrease,the flow index and volumetric flow rate increase,respectively.Compared with CA solution,the viscosity coefficient of CA/SC-CO₂ solution decreases by 19.44%at 50°C and 1.20m L?g^-1,the viscosity decreases by 15.53%at 10s^-1,the die pressure decreases by 14.87%and the volumetric flow rate decreases by 37.75%at 10r?min^-1.The plasticizing effect of SC-CO₂on CA solution in extrusion processing is consistent with the increasing temperature or the increasing solvent ratio.The shear viscosity of the CA and CA/SC-CO₂ solutions gradually decreases with the increase of temperature or screw speed,solvent ratio.When the temperature exceeds 50°C,the shear viscosity of the CA/SC-CO₂ solution decreases unobviously.From 6r?min^-1 to 8r?min^-1,the larger decrease in shear viscosity of the CA and CA/SC-CO₂ solutions.The shear viscosity sensitivity index and the viscous activation energy of CA and CA/SC-CO₂solutions gradually decrease with the increase in temperature.The die pressure of CA and CA/SC-CO₂solutions gradually decrease with the increase of temperature or solvent ratio,and continuously increase with the increase of screw speed.From 40°C to50°C,the larger decrease in die pressure of the CA and CA/SC-CO₂ solutions.The volumetric flow rate of the CA and CA/SC-CO₂ solutions gradually increase with the increase in temperature or screw speed,solvent ratio.With the increase of screw speed,the little change in the impact strength of pure CA products,while the increase in the impact strength of CA products with the assistance of SC-CO₂.The impact strength of CA products with SC-CO₂gradually decreases with the increase of SC-CO₂gas flow rate or temperature,solvent ratio.When the gas injection flow rate exceeds 0.03mL·min^-1 or the temperature exceeds 55°C,the solvent ratio exceeds 1.20mL·g^-1,the cells appear to merge and collapse in the CA products.