硼掺杂石墨烯/苯并噁嗪-环氧树脂高性能纳米复合材料的构筑和陶瓷化成炭机制的研究

Aiming to overcome the current problems of brittleness, flammable, low thermal resistance and low char yielding during combustion of aircraft epoxy resins, POSS-containing benzoxazine with self-toughening, flame retardant effect, char formation and aromatic structures will be synthesized; meanwhile, boron doped graphene nanosheets serving as flame retardant synergist and charring agent will also be fabricated; subsequently, POSS-containing benzoxazine and boron doped graphene are to be incorporated into epoxy matrix to obtain high performance boron doped graphene/benzoxazine-epoxy nanocomposites. The effect of the structure of POSS-containing benzoxazine and the interfacial behaviors and dispersion state of boron doped graphene on the thermal stability and mechanical properties of the epoxy nanocomposites will be investigated, the relationship between structure and properties of the epoxy nanocomposites will be discussed, and the reinforcing mechanisms on the strength, toughness and thermal resistance will be clarified. Furthermore, systematic investigation will be emphasized on the flame retardant properties of the epoxy nanocomposites, and the compositions and structures of the gas and condensed phase products of the resultant epoxy nanocomposites during pyrolysis and combustion processes will be evaluated to find out the flame retardant mechanism. Also, the silicon and boron elements affecting the ablation resistance of the epoxy nanocomposites (including the composition, structure, morphology and thermal oxidative resistance of the char formed) will be studied to demonstrate the ceramic char forming mechanism. The implementation of this project will pave the way for the theoretical and experimental basis for the development of high performance epoxy nanocomposites with reinforced strength, toughening, thermal resistance, flame retardancy and ablation resistance.

本项目针对航空航天领域用环氧树脂存在性脆、易燃、耐热性较差以及成炭率较低等缺点，设计合成兼具芳杂环结构、自增韧侧基和阻燃元素的反应型苯并噁嗪，同时利用硼掺杂石墨烯具有优良的协效阻燃和催化成炭的性质，制备高性能硼掺杂石墨烯/苯并噁嗪-环氧树脂纳米复合材料。研究含POSS基团的苯并噁嗪的结构组成以及硼掺杂石墨烯的界面特性和分散状态对环氧树脂纳米复合材料的力学性能和热稳定性的影响规律，探讨材料的结构、组成和性能之间的关系，揭示含POSS基团的苯并噁嗪和硼掺杂石墨烯对环氧树脂基体的增强增韧以及耐热机制；系统研究材料的阻燃性能以及在燃烧过程中气相和凝聚相产物的变化规律，揭示环氧树脂纳米复合材料的阻燃机理；研究材料的耐烧蚀性能，分析硅和硼元素对炭层的结构组成、形貌和抗氧化性的影响，阐明材料的陶瓷化成炭机理，为研究开发具有增强增韧、耐热、阻燃和耐烧蚀的高性能环氧树脂纳米复合材料提供实验依据和技术支持。

在先进复合材料家族中，环氧树脂以其良好的粘接性、力学性能、化学稳定性、收缩率低和加工成型容易等优点，是目前应用最为普遍的树脂基体。但是，环氧树脂也存在一些固有的缺陷，如脆性大、耐热性不高、易燃烧以及成炭性较差等。本项目针对航空航天领域用环氧树脂存在性脆、易燃、耐热性较差以及成炭率较低等缺点，设计合成了具有自增韧、阻燃、耐热的反应型苯并噁嗪，并结合纳米复合、协效阻燃及陶瓷化成炭的原理，制备出兼具增强增韧、阻燃和耐烧蚀的硼掺杂石墨烯/苯并噁嗪-环氧树脂纳米复合材料。研究了硼掺杂石墨烯/苯并噁嗪-环氧树脂纳米复合材料的力学性能、热稳定性及阻燃性能，揭示了材料的阻燃机理和陶瓷化成炭机制。本项目制备出一系列高性能阻燃环氧树脂纳米复合材料，如拉伸强度达到60 MPa以上，冲击强度提升20%以上，极限氧指数达到30%以上，达到UL-94 V-0级，残炭量在30%以上。研究成果发表了SCI 收录论文8篇，申请发明专利2项，培养博士研究生3人，硕士研究生3人。本项目的实施对研究开发具有增强增韧、耐热和阻燃的高性能环氧树脂纳米复合材料提供理论和技术支持。