Effect of the Spin-Line Temperature Profile on the Translocation of the Solidification Point and Jet Thinning in Unconfined Melt Electrospinning
Effect of the Spin-Line Temperature Profile on the Translocation of the Solidification Point and Jet Thinning in Unconfined Melt Electrospinning
复制标题
无侧限熔体静电纺丝中纺丝线温度分布对凝固点移位和射流稀化的影响
DOI：
10.1021/acsapm.0c01082
复制
发表时间：
2021
影响因子：
5
通讯作者：
Gorga, Russell E.
中科院分区：
文献类型：
--
作者：
Shabani, Elnaz;Yancheshme, Amir Azimi;Ronen, Avner;Gorga, Russell E.
这项工作旨在提供有效的策略和实用的工具来控制纤维的直径，这是自由表面熔体静电纺丝应用中的一个长期挑战，主要是通过突出凝固点的重要性。通过背光成像技术和计算流体动力学数值模拟，实验开发了一种系统的方法来映射熔体静电纺丝过程中电流体动力学射流中的凝固点和温度分布。研究了不同的纺丝线温度分布对工艺的鲁棒性以及纤维形态的影响。扫描电子显微镜分析表明，在高自旋线温度分布，纤维直径下降了四倍相比，室温自旋线环境。无论是在原位背光图像的射流在自旋线和数值相分数分析显示，立即凝固的射流，这是延长两次的情况下，高自旋线温度分布。作为延迟凝固的结果的高自旋线温度分布的伸长的冻结长度被确定为有助于射流变薄和随后的纤维直径减小的主要因素之一。基于模拟，射流的温度曲线表明，在非凝固部分（凝固长度）中沿射流长度沿着下降约20 °C，提出粘度下降是纤维直径减小机制中的第二个因素。最终，板上的熔融膜厚度被确定为半物理限制参数，控制所形成的锥体的尺寸和随后的纤维直径，尽管无限制熔体电纺丝的自由表面性质。
This work aims to provide effective strategies and practical tools to control the diameter of fibers, a long-lasting challenge in the application of free surface melt electrospinning, mainly by highlighting the importance of the solidification point. A systematic approach to mapping the solidification point and temperature profile in an electrohydrodynamic jet in the melt electrospinning process was developed experimentally through the backlit imaging technique and numerically through computational fluid dynamics. The effect of the different spin-line temperature profiles on the robustness of the process as well as the fiber morphology was investigated. Scanning electron microscopy analysis demonstrated that at high spin-line temperature profiles, the fiber diameter dropped by four times compared to the room temperature spin-line environment. Both in situ backlit images from the jets in the spin line and the numerical phase fraction analysis revealed an immediate solidification of the jet, which is elongated twice in the case of the high spin-line temperature profiles. The elongated freezing length for the high spin-line temperature profiles as a result of the delayed solidification was identified as one of the main factors contributing to the jet thinning and subsequent fiber diameter reduction. Based on the simulation, the temperature profile of the jet demonstrated an approximately 20 °C drop along the jet length in the nonsolidified portion (freezing length), proposing the viscosity drop as a second factor in the fiber diameter reduction mechanism. Ultimately, the molten film thickness on the plate was identified as a semiphysical confinement parameter, controlling the size of the formed cones and subsequently the fiber diameter, despite the free surface nature of the unconfined melt electrospinning.