基于界面结构调控构筑高效柔性中子屏蔽复合材料的研究

It is of great significance to shield neutron radiation emissions in order to protect human health and ensure equipment safety. The uniform dispersion of thermal neutron absorption borate fillers in hydrogen-rich polymer matrix is one of the key factors that have great influence in the neutron shielding performance of flexible neutron shielding composites. Interfacial structure control of the polymer and boride fillers to enhance the interfacial interactions have been proved to be effective to solve the problem of dispersion of borate fillers. However, the traditional surface modification methods would cause the problems like processing difficulty, weak interfacial interactions between the substrate and adhesive layer. This project intends to learn from the adhesion mechanism of Marine mussels to synthesize catechol molecules with unsaturated bond, which is similar to the structure of adhesion proteins. We would use self-assembled monolayers to provide hydrogen bonds at the molecular scale interface, which would greatly improve the interfacial adhesion between catechol molecules and boron nitride, and the interfacial interactions between boron nitride and EPDM would be improved. Moreover, it forms direct chemical bridge with EPDM during the vulcanization process, and thus would realize the uniform dispersion of boron nitride in EPDM, so we would obtain the high-efficiency and flexible neutron shielding materials. The implementation of the project is expected to improve the shielding efficiency of neutron materials in the fields of national defense and military industry, aerospace and nuclear energy, provide a new path for the design of neutron shielding materials, broaden the application of neutron shielding materials.

中子辐射的有效屏蔽对于确保操作人员的安全性、设备的可靠性具有重要的意义。具有热中子吸收作用的硼化物填料在富含氢元素聚合物基体中的均匀分散是影响中子屏蔽性能的关键因素之一，而通过对聚合物与硼化物填料的界面结构调控来增强界面作用力是解决填料分散不均的有效途径。然而，传统改性方法会引起加工困难、与基底的作用力较弱等问题。启发于贻贝的粘附机理，本项目拟设计合成一类含不饱和键的邻苯二酚类分子，利用自组装单分子层手段提供在分子尺度界面上的氢键作用，极大地增强其与羟基氮化硼之间的粘附强度，由此可提高氮化硼与三元乙丙橡胶基体之间的界面作用力，然后在硫化过程中与三元乙丙橡胶基体直接形成化学桥接，实现氮化硼在三元乙丙橡胶基体中的均匀分散，提高柔性复合材料的中子屏蔽效率。本项目的顺利实施有望提升国防军工、航天、核能等领域中所需柔性中子屏蔽材料的屏蔽效率，为设计中子屏蔽材料提供新思路，拓宽中子屏蔽材料的应用。

针对国防军工、航天、核能等领域中所需柔性中子屏蔽材料的迫切需求，具有热中子吸收作用的硼化物填料在富含氢元素的橡胶基体中的有效分散是提高中子屏蔽效率的有效途径。本项目致力于对橡胶基体与硼化物填料的界面结构调控来增强界面作用力从而解决硼化物填料分散不均问题，该项目开展了硼化物填料的界面结构调控与表征、具有交替多层结构新型柔性中子屏蔽材料的构建及中子屏蔽性能研究。针对硼化物填料界面结构调控及表征研究，本项目成功合成了含有不饱和键的邻苯二酚类分子，通过对氮化硼填料的羟基化处理，含不饱和键邻苯二酚类分子与羟基氮化硼形成的氢键作用极大地增强其与羟基氮化硼之间的粘附强度，提高了氮化硼与三元乙丙橡胶基体之间的界面作用力，利用表面接触角测试及光学电镜等手段验证了改性氮化硼在三元乙丙橡胶基体中的分散效果显著提升。同时本项目采用多层共挤出技术构建了具有不同层数的交替多层结构的EPDM/(EPDM/BN)，通过硫化成型获得了不同层数的柔性中子屏蔽材料。采用了中子散射谱仪平台开展了中子屏蔽性能的表征；采用万能拉伸试验机对不同层数的柔性中子屏蔽材料力学性能进行了表征；采用了LFA闪射法导热仪对柔性中子屏蔽材料的导热性能进行了表征；研究表明，通过对填料的界面结构调控，复合材料的中子屏蔽性能、力学性能和导热性能均有所提升，同时，交替多层结构有利于中子屏蔽材料力学性能的提升。本项目所研究的柔性中子屏蔽材料可为设计中子屏蔽材料的设计提供理论基础和技术方案支撑。