超临界二氧化碳在螺杆挤出过程中塑化混合酯发射药的研究:在线流变仪设计与实验测量

Study on Mixed Ester Gun Propellent Plasticized with Supercritical Carbon Dioxide during Screw Extrusion:In-line Rheometer Design and Experimental Measurement

为了改善混合酯发射药的加工流动性,在其挤出过程中注入超临界二氧化碳(SC-CO_(2))作为增塑剂;为了更好地研究塑化过程,设计制造了一个在线狭缝流变仪用来测量混合酯发射药的剪切黏度和流变参数。流动曲线表明,混合酯发射药和SC-CO_(2)/发射药混合物都是非牛顿假塑性流体,幂律模型可以用来描述SC-CO_(2)/发射药混合物的流变行为。实验研究了剪切黏度随加工温度和增塑剂含量的变化规律,结果显示较高的加工温度有利于降低剪切黏度。在注入SC-CO_(2)后,黏流活化能降低了约20 kJ/mol。SC-CO_(2)被证明是一种有效的增塑剂,可以显著改善混合酯发射药的流动性。并且随着SC-CO_(2)含量的增加,挤出过程中的流动性会更好,但增塑剂含量的不断增加并不能无限制地提升塑化效果。

In order to improve the processing fluidity of mixed ester gun propellent,supercritical carbon dioxide(SC-CO_(2))as a plasticizer was injected during extrusion.For better observation of plasticization,an in-line slit die rheometer was constructed 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-CO_(2)/propellant mixture are non-Newtonian pseudoplastic fluids.The power model is appropriate to describe the rheological behavior of SC-CO_(2)/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 20 kJ/mol after SC-CO_(2)injection.SC-CO_(2)was shown to be an effective plasticizer that significantly improved fluidity.More SC-CO_(2)leaded to a more ideal fluidity during extrusion,but continuously increasing plasticizer content could not lead to better plasticization without limit.