无定型硼粉/硅橡胶复合材料的耐γ辐射老化性能

Resistance of amorphous boron powder/silicone rubber composites to gamma radiation aging

在核医学、航空和航天等尖端领域中,高分子材料因长期暴露于电离辐射等极端环境而面临严峻挑战,对材料的服役可靠性提出了极高的要求,因此,提升高分子材料的耐辐射老化性能成为迫切需求。无定型硼粉(B)外层存在的空轨道能够提供一个与自由基相互作用的空轨道,并与辐照产生的自由基反应,从而保护高分子材料减少辐射损伤。本工作据此制备了无定型硼粉/硅橡胶(B/SR)复合材料,并通过系统研究辐照前后材料的机械、热学及交联密度等性能变化,深入探讨了B对硅橡胶耐辐射性能的影响。实验结果表明:B/SR0.3样品在吸收剂量为200 kGy时,其断裂伸长率保持率可维持在(49.4±3.1)%,而纯SR仅为(24.7±2.7)%;0.3份B的加入使辐照后硅橡胶复合材料的初始分解温度从454.9℃提升至472.8℃,显著增强了硅橡胶在辐射环境中的热稳定性。同时采用紫外灯-电子顺磁共振(UV-EPR)谱仪进行实时测量,揭示了B可以有效清除辐照过程中硅橡胶复合材料内部产生的自由基。本研究为提升硅橡胶复合材料的耐辐射性能提供了有效策略,同时也为开发新型耐辐射高分子材料奠定了坚实基础。

In cutting-edge fields such as nuclear medicine,aviation,and aerospace,polymer materials face severe challenges owing to long-term exposure to extreme radiation environments.These environments impose stringent requirements on the service reliability of materials,which makes it imperative to improve the radiation resistance and aging resistance of polymer materials.To this end,amorphous boron powder(B)was used to prepare amorphous boron powder/silicone rubber(B/SR)composites because of the possible radical-scavenging characteristics of the empty orbitals present on the outer layer of amorphous boron powder.The impact of B on the radiation resistance of silicone rubber was investigated through systematic studies on the changes in the mechanical,thermal,and crosslink density properties of the material before and after irradiation.The experimental findings demonstrated that,at an absorbed dose of 200 kGy,the retention rate of elongation at break of B/SR0.3 sample can be maintained at(49.4±3.1)%,whereas pure SR is only(24.7±2.7)%.The initial breakdown temperature of irradiated silicone rubber composites raised from 454.9℃ to 472.8℃ by adding 0.3 parts of B,which significantly enhanced its thermal stability in radiation environments.To visually demonstrate the changes in the internal radicals of the silicone rubber composite during irradiation,this study used a UV lamp-electron paramagnetic resonance(UV-EPR)spectrometer for real-time monitoring and revealed that B could effectively eliminate the free radicals generated in the silicone rubber composite during the irradiation process.This study provides an effective strategy to improve the radiation resistance of silicone rubber composites and lays a solid foundation for the development of novel radiationresistant polymer materials.