自旋线温度曲线对无约束熔体静电纺丝中凝固点移位和射流稀化的影响,ACS Applied Polymer Materials

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自旋线温度曲线对无约束熔体静电纺丝中凝固点移位和射流稀化的影响
ACS Applied Polymer Materials ( IF 4.4 ) Pub Date : 2020-12-17 , DOI: 10.1021/acsapm.0c01082
Elnaz Shabani ₁ , Amir Azimi Yancheshme ₂ , Avner Ronen _{3,

4} , Russell E. Gorga ₁

Affiliation

这项工作旨在提供有效的策略和实用工具，以控制纤维的直径，这对自由表面熔体静电纺丝的应用是一个长期的挑战，主要是通过突出固化点的重要性。通过背光成像技术并通过计算流体力学进行数值模拟，实验性地开发了一种系统的方法来绘制熔体静电纺丝过程中电动流体射流中凝固点和温度曲线。研究了不同纺丝温度曲线对工艺鲁棒性以及纤维形态的影响。扫描电子显微镜分析表明，在高纺丝线温度曲线下，与室温纺丝线环境相比，纤维直径下降了四倍。来自旋转线中喷嘴的原位背光图像和数值相分数分析均显示了喷嘴的立即凝固，在高旋转线温度曲线的情况下，该喷嘴被拉长了两倍。延迟凝固导致高纺丝线温度曲线延长的凝固长度被认为是造成射流细化和随后纤维直径减小的主要因素之一。基于模拟，射流的温度曲线显示未凝固部分沿射流长度（冻结长度）下降了约20°C，这表明粘度下降是纤维直径减小机制中的第二个因素。最终，将板上的熔融膜厚度确定为半物理约束参数，

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Effect of the Spin-Line Temperature Profile on the Translocation of the Solidification Point and Jet Thinning in Unconfined Melt Electrospinning

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.

更新日期：2021-01-08

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