新型聚芳醚纤维成纤过程中大分子的有序化及非晶取向行为研究

Poly (aromatic ethers) polymers containing phthalazinone moieties are novel high-temperature resistant polymers. Our previous study demonstrates that a series of poly (aromatic ethers) polymers such as poly(phthalazinone ether ketone)s (PPEK) and poly(phthalazinone ether sulfone ketone)s (PPESK) can be spinned to the fibers with excellent chemical resistant and higher mechanical properties by using a low consumpted solution spinning method. Moreover， this new kind of fiber is amorphous， which is different from the tranditional high-performance fibers with high crystallinities. In this case, controlling of molecular chains ordering and amorphous oritention is a key to promote the mechanical properties of amorphous poly (aromatic ethers) fibers. However, the characterization of amorphous orientation is difficult and the relationship between morphology and mechanical properties for amorphous PPEK and PPESK fibers are rarely reported before. This project focuses on the macromolecular odering and amophous orientation behaviors of amorphous poly (aromatic ethers) fibers in the flow field of fabrication processing during spinning.In this research the birefringence, intensity distribution of X-ray diffraction and synchrotron will be adopted to measure the as-spun fibers and heat-treated fibers. The radial distribution function will be used to characterize the distribution of molecular chains in amorphous. And the orientation distribution function will be used to characterize the orientation behavior of amorphous structure with partly oriented segments.Besides the off-line analysis of morphology, the on-line measurement of the evolvement of orientation behavior during heat-treatment and elongation will be approached. The achievements of this research will provide some important theoretic basis for the development of amorphous PPEK and PPESK fibers as a novel heat-resistant fibers. It will also be significant for the improvement of high-performance fibers with very low crystallinity such as polyimide fibers.

含二氮杂萘酮结构聚芳醚树脂是一类特种耐高温聚合物。前期实验证明，该类树脂采用溶液纺丝工艺可制成低成本、强度较高的纤维。区别于传统的结晶性高性能纤维，新型聚芳醚纤维是非晶的。无定形区大分子的取向控制是提高纤维力学性能的关键要素。然而无定形的取向结构的表征和模拟，一直是学术界的难题。 本项目重点研究新型聚芳醚纤维纺丝流动场中大分子的有序化和无定形区的取向结构的控制和表征方法论。采用双折射、常规X-射线衍射仪和同步辐射设备等对纤维的结构进行多尺度解析，采用径向分布函数对无定形区的分子链间距、采用取向分布函数对非晶取向态的局部有序结构进行表征，构建聚集态结构模型。结合纤维热拉伸过程中结构演变的原位检测和动态粘弹谱分析，构建无定形-非晶取向结构与力学性能关系理论模型。研究成果将为以非晶为特征的新型聚芳醚耐高温纤维的应用提供理论指导。

含二氮杂萘酮联苯结构（DHPZ）聚芳醚树脂（PPEK）是一类新型可溶解耐高温聚合物，是一种耐高温无定形高分子材料，在航空航天等诸多领域有着重要应用前景。本项目探讨其作为耐高温纤维的应用前景，重点研究其可纺性和纺丝过程的聚集态结构，尤其是无定形大分子取向结构的演变，研究微米级连续纤维及纳米级电纺丝的结构调控及应用。主要成果如下：.1）研究了含DHPZ单体结构的一些列聚合物溶液的流变特性，优化了聚合物溶液干法纺丝参数，改造了纺丝设备的热处理和牵伸装置，优化了多道牵伸速度的匹配和温度调节，成功得到了PPEK连续纤维。.2）区别于常规半结晶纤维的取向结构研究方法，关于无定形纤维的取向结构几乎没有定量研究，本项目首次通过X射线衍射强度的精细解析，采用径向分布函数对取向的无定形分子链间距做出了定量计算，证明了与纤维轴不同夹角取向的无定形分子链间距不同，并通过外加张力下X射线衍射强度的变化，计算了相邻PPEK分子链间的模量，证明PPEK在成纤过程中相邻分子间具备足够的相互作用力使其凝聚成型。.3）通过电纺获得了有序排列的PPEK微纳米纤维，实现了对无定形纳米纤维聚集态结构和性能调控。通过取向的PPEK微纳米纤维与结晶性聚合物聚对苯二甲酸丁二醇酯（PBT）微纳米纤维的对比研究，阐明了无定形刚性链聚合物纳米纤维中分子链和微观结构的取向对大分子刚性和几何特征的依赖性。.4）通过PPEK与聚偏氟乙烯(PVDF)复合溶液电纺微纳米纤维，分析了纳米尺寸下刚性链对柔性链的运动性、结晶性以及聚集态结构的影响。通过刚性链和柔性链之间相互作用的调控，实现了复合纤维中物理交联、聚集态结构和力学性能的变化，研究了其介电性能及其作为高性能锂离子电池隔膜材料的应用。.项目研究期间，发表学术论文11篇，培养博士毕业生2人，硕士毕业生2人，尚未毕业的博士和硕士研究生3人，在结题后该三名学生将继续本项目的延伸研究。