CA/RDX复合材料超临界CO_2间歇法微孔发泡研究（英文）

Microcellular Foaming of CA/RDX Composites in a Batch Supercritical CO_2 Process

以醋酸纤维素(CA)为黏结剂,黑索今(RDX)为含能组分,通过超临界二氧化碳(SC-CO_2)间歇法发泡技术制备了微孔可燃复合材料CA/RDX。采用重量法研究了SC-CO_2在该复合材料中的吸收与解吸收过程,同时利用Fickian扩散定律,研究了SC-CO_2的扩散系数。采用扫描电子显微镜(SEM)研究了发泡温度和饱和压力对该材料内部形貌的影响规律。结果表明,CO_2的吸收量与扩散系数随着饱和压力的提高而增加,在20MPa,40℃饱和条件下达到最大饱和量11.16%。RDX和CA界面降低了微孔异相成核能垒,因此增加了微孔成核速率,微孔产生于RDX和CA界面间的微裂纹并逐步长大成为完整的气泡;在微孔成核后,微孔尺寸随饱和温度与发泡温度差(ΔT)的增加而增大;由于CO_2解吸收过程中扩散系数随饱和压力的增加而增加,因此饱和压力对泡孔形貌的影响不明显。

Microcellular combustible composites CA/RDX,based on cellulose acetate(CA)as binder and RDX as energetic component,were fabricated by the two-step microcellular foaming in supercritical CO_2.The sorption and desorption behaviour of SC-CO_2 in the composites were investigated by a weighing process,and the diffusivity was analyzed by Fickian diffusion.Scanning Electron Microscopy(SEM)was used to investigate the influence of foaming temperature and saturation pressure on the foamed structures.The results indicate that the CO_2 sorption amount increases with the sorption pressure and the largest sorption amount reached to 11.16% at 20 MPa and 40℃,with a corresponding increase in sorption diffusivity.The presence of a RDX/CA interface can reduce the activation energy barrier to nucleation,thereby increasing the nucleation rate.The micropores generate from microcracks between RDX particles and the CA binder,and develope into viable bubbles.Once the nucleation has occurred,the driving force for cell growth is directly related to the increased temperature from saturation temperature to foaming temperature(ΔT).The pore size increases withΔT.Simultaneously,the effect of saturation pressure is not evident as the foaming temperature,for the effect of pressure,was weakened by an increased diffusion coefficient.