Polyamide 4 (PA4) is a lactam-based aliphatic synthetic polymer with promising properties and admirable biodegradability. In this study, oriented PA4 fibers were fabricated by dry spinning followed by thermal drawing. Elastic modulus (El) of the crystalline regions (crystal modulus) of PA4 fibers in the direction parallel to the chain axis was evaluated from the X-ray diffraction peak shift owing to the tensile stress. The apparent El value of PA4 is 67 GPa for meridional 004 reflection and 119 GPa for 0010 reflection, respectively. The reason for the different El is that the decrease of crystallite size of PA4 by the applied stress brought extra shifts of 004 reflection peak to lower angle based on the Laue factor. In contrast, 0010 reflection peak received less effects from this effect, and the El value of 119 GPa obtained from 0010 reflection was considered to be a reliable value. The observed El value of PA4 is much lower than the calculated values assuming fully extended planar zigzag skeleton for PA4. Thus the low El value is attributed to the highly contraction (−1.9 %) from the fully extended conformation as observed for another polyamides.

中文翻译：

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聚酰胺 4 的微观结构和晶体模量在平行于链轴的方向上α


聚酰胺 4 （PA4） 是一种基于内酰胺的脂肪族合成聚合物，具有广阔的性能和令人钦佩的生物降解性。在这项研究中，通过干纺和热拉丝制备了取向 PA4 纤维。从拉伸应力引起的 X 射线衍射峰偏移评估了 PA4 纤维在平行于链轴的方向上晶体区域（晶体模量）的弹性模量 （El）。PA4 的表观 El 值分别为 67 GPa（经向 004 反射）和 119 GPa（0010 反射）。El 不同的原因是 PA4 的晶粒尺寸因施加的应力而减小，导致 004 反射峰向基于 Laue 因子的较低角度的额外偏移。相比之下，0010 反射峰受到这种效应的影响较小，从 0010 反射获得的 119 GPa 的 El 值被认为是一个可靠的值。观察到的 PA4 的 El 值远低于假设 PA4 完全伸展的平面锯齿形骨架的计算值。因此，低 El 值归因于从完全伸展构象的高度收缩 （-1.9 %），就像在另一种聚酰胺中观察到的那样。