本质阻燃连续玻璃纤维增强聚酰胺6接枝聚磷腈复合材料的制备、性能及阻燃机理研究

The sustainable development of environmental resources has aroused a worldwide interest in the environmental-friendly flame-retardant materials. Continuous glass fiber reinforced polyamide 6 matrix composites suitable for resin transfer molding process is difficult to be flame retardant. In this project, N-acylcaprolactam polyphosphazene will be synthesized as the activator for caprolactam anionic ring opening polymerization and the flame retardant, which can prepare the environmentally friendly and efficient inherently flame-retardant polyamide 6 grafted polyphosphazene (PA6-g-PPZ). Then the GF/PA6-g-PPZ composites can be prepared. We will develop controllable preparation of grafting density and molecular weight of PA6 grafted to polyphosphazene molecular chains. The influence discipline of molecular chain structure of PA6-g-PPZ on crystallization behavior, mechanical properties, heat resistance and flame retardancy will be mainly revealed. The formation of interfacial microstructure of GF/PA6-g-PPZ composites will be analyzed after modifying the surface of glass fiber. The relationship between the structure and properties of the composites will be identified and its flame retardant mechanism will be clarified. These results will further provide the theoretical guidelines for the optimization design of molecular chain structures of inherently flame-retardantPA6-g-PPZ and lay a theoretical foundation for the development of GF/PA6-g-PPZ composites with excellent comprehensive performance.

环境资源的可持续发展使得绿色环保本质阻燃材料的研究在国际上备受关注。针对适合树脂传递模塑成型工艺制备连续GF增强PA6树脂基复合材料难以阻燃的问题，本项目通过分子设计合成N-酰基己内酰胺化聚磷腈作为己内酰胺单体进行阴离子开环聚合的大分子活化剂兼阻燃剂，制备环保高效本质阻燃PA6接枝聚磷腈（PA6-g-PPZ）树脂，进一步制备连续GF/PA6-g-PPZ复合材料。开展阴离子聚合PA6在PPZ分子链上的接枝密度及其分子量的可控制备，揭示PA6-g-PPZ树脂分子链结构对其结晶行为、力学性能、耐热性能及阻燃性能的影响规律；通过对GF表面进行改性，分析连续GF/PA6-g-PPZ复合材料界面微观结构的形成，明确复合材料微观结构与性能之间的关系，阐述其阻燃机理，为进一步优化设计本质阻燃PA6-g-PPZ的分子链结构提供理论依据，为开发综合性能优异的连续GF/PA6-g-PPZ复合材料奠定理论基础。

采用RTM成型的连续GF/PA6复合材料可以得到形状复杂的构件，且力学性能优异，在汽车领域具有广泛的应用前景。但适合RTM成型工艺的阻燃剂要求可以溶解或共熔融于在己内酰胺熔体中，且不影响聚合活性，同时其熔体粘度须低于1 Pa·s。本研究从分子结构设计出发，成功合成了PA6接枝聚磷腈（PA6-g-PPZ），研究了PPZ含量对PA6-g-PPZ结构性能的影响，发现随着PPZ含量的增加，PA6-g-PPZ的阻燃性能增加，但机械性能降低。由于PA6-g-PPZ与PA6树脂基体具有较好的相容性，采用高PPZ含量的PA6-g-PPZ为阻燃剂。发现随着PA6-g-PPZ含量的增加，PA6树脂的阻燃性提高，同时冲击韧性提高。由于PA6-g-PPZ树脂的分子量较大，加入己内酰胺熔体中引起树脂熔体粘度增大，因此不能加入大量的PA6-g-PPZ，从而对提高GF/PA6复合材料的阻燃性效果不明显。下一步我们将向PA6-g-PPZ分子链中引入残炭率高的官能团或设计合成高残炭率的环磷腈作为RTM成型的连续GF/PA6复合材料的阻燃剂，提高复合材料的阻燃性。