含杂萘联苯结构低温固化邻苯二甲腈树脂及结构性能研究

Phthalonitrile resins can form s-triazine structure after thermal curing, they have been widely used as matrices in advanced technologies, such as aerospace fields, due to their excellent comprehensive properties including long-term use at high temperature. However, the bottleneck problems of high temperature and long reaction period during curing have not been solved yet. In order to improve the above situation, in this project, Lewis acid-base composite curing agents were designed based on our previous work, and the curing reaction rates can be enhanced through synergetic curing, therefore, the curing temperature of phthalonitrile resins can be reduced. Meanwhile, with the help of molecular design, the twisted, noncoplanar phthalazinone moieties were introduced into the backbone of phthalonitrile resins, to develop a new kinds of thermosetting resins with higher heat resistance. Through investing the curing kinetics, optimizing the contents of Lewis acid-base composite curing agents and curing conditions, regulating the molecular chain structure of resins, the phthalonitrile resins bearing phthalazinone moieties was obtained, which can be cured at low temperature and showed excellent properties. Furthermore, the curing mechanism of phthalonitrile over novel curing agent also was tested, and the relationship between the molecular chain structure, curing agent and the comprehensive properties of resin were studied. This project will dissolve the scientific problem of high curing temperature and long reaction period during curing, which restrict the development of phthalonitrile resins, enrich the theory of designing these resins, and provide theoretical and practical basis for engineering phthalonitrile resins.

邻苯二甲腈树脂固化后可形成三嗪环结构，具有可在高温下长期使用等优异综合性能，在航天航空等高新技术领域具有广阔的应用前景。然而，该类树脂的固化工艺存在固化温度高、固化时间长的瓶颈问题始终未能得到实质性的解决。针对上述问题，本项目在前期工作基础上，设计Lewis酸-碱复合固化剂，通过协同固化，提高树脂固化速率，实现邻苯二甲腈树脂的低温固化。同时从分子结构设计出发，将扭曲、非共平面的杂萘联苯结构引入到邻苯二甲腈树脂分子主链中，开发一类耐热等级更高的热固性树脂。通过研究固化反应动力学，优化Lewis酸-碱复合固化剂及其固化工艺，调变树脂分子链结构，获得性能优异的可低温固化的含杂萘联苯结构邻苯二甲腈树脂。阐明新型固化体系的固化机理，揭示树脂分子链结构及固化剂组成对树脂综合性能的影响规律。解决制约邻苯二甲腈树脂发展的固化温度高、时间长的科学难题，丰富此类树脂设计理论，为其工程化提供理论支撑与实验依据。

本项目针对制约邻苯二甲腈树脂应用发展的固化工艺中固化温度高、固化时间长的关键科学问题，通过设计高性能的固化剂和具有低熔点的树脂前驱体实现邻苯二甲腈树脂固化工艺的改善。首先制备了四种Lewis酸-碱复合固化剂，包括氯化锌/尿素、氯化锌/4,4′-二氨基二苯砜（DDS）、氯化亚铜/DDS、氯化锌/三聚氰胺。通过非等温差示扫描量热法考察了不同固化体系的固化动力学，研究了其协同固化的特点，系统考察了复合固化剂中Lewis酸-碱的种类、组成和用量对固化工艺和树脂综合性能的影响，实验发现复合固化剂可以有效降低固化体系的固化温度和缩短固化时间。例如，氯化锌/尿素复合固化剂在300oC条件下可以完成对间苯二酚基邻苯二甲腈前驱体的固化，固化后树脂的热稳定性比以氯化锌为固化剂、在375oC下固化的要高很多，甚至可以和氯化锌在400oC固化条件下的相媲美，固化时间也由一般体系的大于20小时缩短到6小时。另外，分别制备了儿茶素基和三酚A基的邻苯二甲腈树脂前驱体（CA-Ph和TPPA-Ph），这两种前驱体不仅具有较低的熔点（<100oC）和熔融黏度，同时可以在不加入任何固化剂的条件下自固化。不仅克服了常用小分子芳香胺固化剂在高温固化条件下分解和升华所造成的树脂缺陷的问题，同时此自固化体系还具有较宽的加工窗口（116 oC）。为继续提高邻苯二甲腈树脂的综合性能，将杂萘联苯引入到邻苯二甲腈树脂前驱体和固化剂的分子结构中，分别制备得到了含杂萘联苯结构的聚芳醚腈邻苯二甲腈前驱体PPEN-Ph和氨基封端杂萘联苯聚芳醚酮齐聚物A-PPEK。TGA结果显示A-PPEK的5%热失重温度比常用的固化剂DDS高出69.3oC。同时尝试将双官能度的酸性离子液体作为PPEN-Ph的固化剂，其固化活性优于常用的固化剂ZnCl2，同时其固化得到的邻苯二甲腈树脂表现出了更为优异的热稳定性。上述工作对拓展具有优异综合性能的邻苯二甲腈树脂在航空航天、船舶、汽车等领域的应用提供了理论指导和实践借鉴。..