Study On Interfacial Properties And Numerical Simulation In Twin Screw Extrusion Of CL-20-Propellants Substitute

CL-20,as one of new cage polyamine compounds,has the advantages of high density and high energy.With the development of military science,the research based on CL-20 propellant is a hotspot,and the research on CL-20 gun propellant is not enough.In this work,CL-20 triple base propellant substitutes were made of melamine,cellulose acetate and glyceryl triacetate,and its microscopic morphology,crystal structure,thermal stability,tensile properties and rheological properties were studied.Scanning electron microscopy(SEM)was used to characterize the microscopic morphology of samples and the results shown that raw materials of CL-20 triple bases propellant substitutes can be uniformly mixed together.The results of infrared spectroscopy shown that the interfacial forces between the materials were enhanced by hydrogen bond from the mixing process.And X-ray diffraction(XRD)was used to study the functional groups and crystal structure,the results shown that there was a crystallization phenomenon throughout the preparation process and the melamine crystal form didn't change.The DSC results shown that the thermal stability of triple basic propellant substitutes was reduced compared with the raw materials.And the interfacial forces of triple base propellant substitutes were verified by mechanical properties from a macro perspective.At last,The rheological test results shown that the viscosity of the CL-20 triple bases propellant substitutes were gradually reduced with the increase of temperature,and its non-Newtonian index decreased first and then increased with the increase of temperature.At the same time,it was found that the particle size of melamine(CL-20)had no regularity effect on viscosity and non-Newtonian index of propellant.Luvodic software was used to simulate the continuous mixing extrusion process of CL-20 triple base propellant substitutes,and the arrangement and combination of screw elements were optimized.Meanwhile,the energy variation in screw extrusion was also analyzed.The rusults shown that the quantity and the position of the compression section had great influence on the energy distribution and the mixing degree of the extrusion process,however,the angle and position of the pinch block was not affect the extrusion parameters of the procedure.There was the better process parameter with the feed rate of 11.1kg/h and screw speed of 45 rpm in the structure of one expansion section and two compression sections(the compression section is in the first and the fourth section).