Study on Mixed Ester Gun Propellent Plasticized with Supercritical Carbon Dioxide during Screw Extrusion:In-line Rheometer Design and Experimental Measurement
Study on Mixed Ester Gun Propellent Plasticized with Supercritical Carbon Dioxide during Screw Extrusion:In-line Rheometer Design and Experimental Measurement
In order to improve the processing fluidity of mixed ester gun propellent,supercritical carbon dioxide(SC-CO2)as a plasticizer was injected during extrusion.For better observation of plasticization,an in-line slit die rheometer was construc-ted to measure the shear viscosity and rheological parameters of mixed ester gun propellent.The flow curves demonstrated that both of gas-free propellant and SC-CO2/propellant mixture are non-Newtonian pseudoplastic fluids.The power model is appro-priate to describe the rheological behavior of SC-CO2/propellant mixture.Experimental measurements of shear viscosity as a function of processing temperature and plasticizer content were conducted.Higher processing temperature was beneficial for reducing shear viscosity.The activation energy to flow decreased about 20kJ/mol after SC-CO2 injection.SC-CO2 was shown to be an effective plasticizer that significantly improved fluidity.More SC-CO2 leaded to a more ideal fluidity during extrusion,but continuously increasing plasticizer content could not lead to better plasticization without limit.
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