It has been well known that increasing the molecular weight of ultra-high weight polyethylene (UHMWPE) has a positive effect on obtaining high-strength fibers, but the structural advantages brought by such event still lack clear-cut verification. This study selects fibers with different molecular weights (MW) and investigates the trend of structure and property changes by controlling the draw ratio (DR) and temperature during hot drawing process. The results show that all fibers can achieve saturation of orientation with the increase of DR, but the strength of the higher MW fiber is significantly larger than that of the low MW ones. Meanwhile, the higher MW brings more shish content and longer shish length. Because higher molecular weight means fewer chain end defects, which has benefit for the formation of continuous shish crystals. As adjusting the shish content and length by means of changing DR and operation temperature, the positive correlations between strength and shish content or shish length are found. Therefore, the effect of MW on strength is due to changes in the crystalline structure of fibers, especially shish content and length are key structural factors for inducing superior strength. This work provides a reference for achieving high-performance fibers through structural regulation.

中文翻译：

---

揭示分子量对高取向 UHMWPE 纤维机械增强的作用


众所周知，增加超高重量聚乙烯 （UHMWPE） 的分子量对获得高强度纤维具有积极作用，但此类事件带来的结构优势仍缺乏明确的验证。本研究选择不同分子量 （MW） 的纤维，并通过控制热拔过程中的牵伸比 （DR） 和温度来研究结构和性能变化的趋势。结果表明：随着 DR 的增加，所有纤维都能实现取向饱和，但高分子量纤维的强度明显大于低分子量纤维;同时，较高的分子量带来更多的 shish 含量和更长的 shish 长度。因为更高的分子量意味着更少的链端缺陷，这有利于形成连续的 shish 晶体。通过改变 DR 和工作温度来调整齿槽含量和齿槽长度，发现强度与齿槽含量或槽长呈正相关。因此，MW 对强度的影响是由于纤维晶体结构的变化，尤其是 shish 含量和长度是诱导优越强度的关键结构因素。这项工作为通过结构调控实现高性能纤维提供了参考。