常压射流等离子体处理含水PPTA纤维微观结构演变及作用机理研究

The presence of moisture in hydrophilic polymer can deepen the treatment effects of atmospheric pressure plasma jet (APPJ) from surface modification to inducing changes in macromolecular aggregation structure. In order to investigate and verify the treatment efficiency and mechanisms of using APPJ to modulate microstructure and improve performance of PPTA fibers during the fiber forming procedure, in this project, the interaction process between APPJ treatment and wet as-spun PPTA fibers is set as research model. The treatment utility would be studied in three aspects: fiber macromolecular aggregation structure, surface microscopic physical and chemical characteristics and performance. The evolution mechanisms on macromolecular aggregation structure of wet PPTA fiber initiated by APPJ treatment would be explored through analyzing the correlation of variations in "fiber moisture contents-intermolecular hydrogen bonds-crystalline structure". Based on the perspective of free radical reaction, the interaction mold of APPJ-H2O-PPTA and its working principle of activating fiber surface microscopic physical and chemical characteristics would also be disclosed. The relationship between fiber structure and performance would be established and finally the synergistic effects of modulating macromolecular aggregation structure and chemical activation during the APPJ-wet PPTA fiber treatment process would be clarified. The implementation of this project aims to lay foundation for developing a new method pattern based on APPJ technology applicable for improving PPTA fiber's microstructure and property during the fiber forming procedure which is one of the key scientific problems referring to developing high performance aramid fiber. The results obtained would provide a new approach and lay scientific basis for solving this problem and be of great theoretical and practical significance.

聚合物中水分的存在可以使常压射流等离子体（APPJ）的作用效果从表面改性深化至调整大分子聚集态结构。为了论证APPJ用于PPTA纤维成型过程调控微观结构和优化性能的功效及作用机理，项目确立以APPJ处理含水PPTA 初生纤维的过程为研究模型，从纤维大分子聚集态结构、表面微观物化结构、性能三个方面系统探讨APPJ对PPTA纤维的影响效用；从纤维含水-分子间氢键-晶态结构的关联机制角度解析APPJ诱导含水PPTA纤维聚集态结构演变的机理；从自由基反应角度揭示APPJ-水-PPTA交互反应“活化”表面微观物化结构的过程原理；建立纤维结构与性能的对应关系，进而阐明APPJ对含水PPTA纤维聚集态结构调整和化学活化协同作用改性的机理。项目研究为建立基于APPJ技术的PPTA纤维结构性能调控方法体系奠定基础，为解决高性能芳纶纤维研制过程中的关键科学问题提供新思路和科学依据，具有重要的理论和实践意义。

聚合物中水分的存在可以使常压等离子体的作用效果从表面改性深化至调整大分子聚集态结构。为了论证常压等离子体用于PPTA纤维成型过程调控微观结构和优化性能的功效及作用机理，项目选择干喷-湿纺制得PPTA初生纤维为研究对象，重点模拟工业生产过程中纤维的含水状态，采用不同工作条件常压等离子体对其进行处理，然后对处理前后纤维的物理化学微观结构及其性能表现进行测试表征，剖析阐释了常压等离子体-纤维中水分-PPTA交互反应“活化”微观物化结构的过程原理，分析了纤维微观结构演变与性能改善的关联变化关系，所取得的主要研究结果如下：1）常压等离子体处理具备诱导PPTA初生纤维高效放湿的效能。研究表明纤维中水分衰减速率与等离子体放电辐射条件密切相关，等离子体活性粒子浓度越大，能量越高，处理时间延长，越有利于纤维内部的间接吸附毛细水析出到纤维表面参与等离子体反应，脱水效率越高；2）适当增加等离子体输入功率，延长处理时长，增加氩气流量等，等离子体处理使纤维表面产生点、块状微细粗糙结构。纤维初始含水率越低，处理后的纤表粗糙程度越小。等离子体处理通过诱导纤维脱水放湿，促使纤维大分子结构中分子间氢键的重建，有利于大分子聚集态结构变得紧密。这使得处理后纤维样品的强度和模量均有不同程度的增加；3）在等离子体的物理刻蚀和化学活化协同作用下，纤维表面粗糙度和和含氧极性基团量增加，使得处理后纤维与树脂基体的界面剪切强度均有不同程度增加，同时也赋予纤维更好的反应活性，有利于在成型制备后处理过程中实现功能化整理；4）采用去质子化法解离PPTA初生纤维可以制得纳米芳纶纤维分散液，采用质子化还原方法可以使芳纶纳米纤维通过分子间氢键重建组装形成新的结构形态。项目研究为PPTA纤维工业生产后处理工艺的创新完善提供数据和理论基础。