开展了鞘气聚焦高效率纺丝射流喷射的研究。搭建了带有微弱电流检测模块的鞘气聚焦电纺喷射实验平台, 讨论了鞘气约束作用下纺丝射流的流变与运动行为, 结合理论模型分析了鞘气供气压强等工艺参数对纺丝电流的作用规律。实验显示: 鞘气聚焦促进了射流的拉伸细化, 降低了射流喷射临界启动电压, 减小了纳米纤维的直径、提高了电纺纳米纤维的均匀性。当供气压强由0 kPa上升到50 kPa时, 射流喷射平均临界启动电压由10.2 kV降低至2.9 kV; 施加电压为4 kV时, 经4.4 s产生峰值为532 nA的冲击电流, 稳定喷射阶段纺丝电流为300~500 nA。 鞘气聚焦还减小了射流直径和表面电荷密度, 纺丝电流减小至没有鞘气聚焦时纺丝电流的1/7; 纺丝电流随着鞘气压强、喷头至收集板距离的增加而降低, 随着施加电压和溶液质量百分数的增加而增大。得到的结果表明: 鞘气聚焦抑制了射流喷射过程的电荷干扰, 减小了纺丝射流直径, 提高了静电纺丝的稳定性。 该方法为改善静电纺丝技术的控制水平提供了新的途径。

How to increase the ejection efficiency of an electrospinning jet by inducing sheath gas focusing was investigated, and an electrospinning experimental setup with sheath gas focusing was built up. The ejection and movement behaviors of electrospinning jet under the sheath gas was analyzed. The effect of some of technological parameters such as the pressure of sheath gas on a electrospinning current was studied based on the theoretical model. The experiments indicate that the sheath gas promotes the stretching and thinning of the electrospinning jet, by which the critical voltage of electrospinning and the diameter and distribution area of a nanofiber have been decreased. As the pressure of sheath gas is increased from 0 kPa to 50 kPa, the critical voltage of electrospinning decreases from 10.2 kV to 2.9 kV. When the applied voltage is 4 kV, the front-end of electrospinning jet takes 4.4 s to reach a collector and produces a peak current of 532 nA. The electrospinning current ranges from 300 nA to 500 nA during the stable ejection process. Moreover, both the diameter and surface charge density of electrospinning jet have been decreased by the sheath gas focusing, and the electrospinning current is only one seventh of that without sheath gas. Under the sheath gas focusing, the electrospinning current decreases with the increasing of gas pressure and the distance between nozzle and collector, but increases with the increasing of applied voltage and the concentration of polymer solution. It concludes that the sheath gas focusing restrains the charge interferences in electrospinning processing, decreases the diameter of electrospinning, improves both the injection stability of electrospinning and uniformity of nanofiber. This work provides a good way to improve the control level of electrospinning technology.