Deformation mechanisms in ionic liquid spun cellulose fibers
Deformation mechanisms in ionic liquid spun cellulose fibers
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DOI：
10.1016/j.polymer.2016.07.007
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发表时间：
2016-09
期刊：
影响因子：
4.6
通讯作者：
N. Wanasekara;A. Michud;Chenchen Zhu;S. Rahatekar;H. Sixta;S. Eichhorn
中科院分区：
文献类型：
--
作者：
N. Wanasekara;A. Michud;Chenchen Zhu;S. Rahatekar;H. Sixta;S. Eichhorn
从离子液体溶剂纺丝系统生产的一系列下一代再生纤维素纤维的分子变形和晶体取向与宏观纤维性质相关。纤维在纺丝阶段被拉伸以增加分子和晶体取向，以实现高拉伸强度和杨氏模量，用于工程应用中的潜在用途。利用拉曼光谱来量化在张力下变形的纤维的分子应变和取向。用X射线衍射仪对纤维的晶体取向进行了表征。这些技术被示出为提供关于纤维的微观结构的补充信息。在拉伸变形下，跟踪从纤维素聚合物链的主链结构发出的特征拉曼带的位置的移动，该特征拉曼带最初位于λ 1095 cm-1。结果表明，这条带相对于应变的位移速率随纤维的拉伸比而增加，表明纤维素链的轴向分子排列和随后的变形增加。纤维的拉曼谱带位移速率与模量之间存在线性关系，表明纤维具有一系列有序排列的晶畴和非晶畴的聚集体结构。广角X-射线衍射数据表明，晶体取向随着拉伸比的增加而增加，并且使用结晶链滑移模型来拟合取向随纤维拉伸比的变化。除此之外，提出了一种新的模型，该模型更好地考虑了纤维的分子变形。使用这个模型的纤维素-II结构的晶体模量的预测（83 GPa），这是在良好的协议与其他实验方法，其确定。
The molecular deformation and crystal orientation of a range of next generation regenerated cellulose fibers, produced from an ionic liquid solvent spinning system, are correlated with macroscopic fiber properties. Fibers are drawn at the spinning stage to increase both molecular and crystal orientation in order to achieve a high tensile strength and Young’s modulus for potential use in engineering applications. Raman spectroscopy was utilized to quantify both molecular strain and orientation of fibers deformed in tension. X-ray diffraction was used to characterize crystal orientation of single fibers. These techniques are shown to provide complimentary information on the microstructure of the fibers. A shift in the position of a characteristic Raman band, initially located at ∼1095 cm−1, emanating from the backbone structure of the cellulose polymer chains was followed under tensile deformation. It is shown that the shift rate of this band with respect to strain increases with the draw ratio of the fibers, indicative of an increase in the axial molecular alignment and subsequent deformation of the cellulose chains. A linear relationship between the Raman band shift rate and the modulus was established, indicating that the fibers possess a series aggregate structure of aligned crystalline and amorphous domains. Wide-angle X-ray diffraction data show that crystal orientation increases with an increase in the draw ratio, and a crystalline chain slip model was used to fit the change in orientation with fiber draw ratio. In addition to this a new model is proposed for a series aggregate structure that takes into better account the molecular deformation of the fibers. Using this model a prediction for the crystal modulus of a cellulose-II structure is made (83 GPa) which is shown to be in good agreement with other experimental approaches for its determination.