环氧树脂及h-BN/环氧树脂复合材料的辐射效应

Radiation effects of epoxy resin and h-BN/epoxy resin composites

环氧树脂(EP)及其复合材料在核工业中有着广泛的应用,对其辐射效应的研究可为开发耐辐射环氧树脂材料提供参考。本工作以四氢邻苯二甲酸二缩水甘油酯(TADE)/甲基六氢苯酐(MHHPA)体系为研究对象,以两种不同平均粒径(7.5μm和757 nm)的氮化硼为填料制备氮化硼/环氧树脂复合材料。采用密度泛函理论(DFT)对环氧树脂交联结构的裂解方式进行了讨论,并研究了两种氮化硼/环氧树脂复合材料受不同吸收剂量的γ-射线辐照前后的力学性能和热稳定性能的变化规律。结果表明:环氧树脂交联点结构所包含的化学键中,异丙醇单元的C-C键键能最低,最易断裂,从而导致高分子交联网络被破坏。吸收剂量超过250 kGy时,环氧树脂及其复合材料的拉伸强度和热分解温度出现明显下降。辐照后的力学强度是BN粒径和添加量综合影响的结果,当吸收剂量达到1100 kGy时,质量分数为3%的n-BN/EP的拉伸强度最大,其热分解温度也最高。因此,少量添加亚微米级尺寸的h-BN可以提升环氧树脂的耐辐射性能。本工作对耐辐射环氧树脂复合材料的开发具有理论和实践指导意义。

Epoxy resin(EP)and its composites have extensive applications in the nuclear industry.The study of their radiation effects can provide critical guidance in developing radiation-resistant epoxy resin materials.In this study,an epoxy resin was synthesized from tetrahydrophthalic acid diglycidyl ester and methylhexahydrophthalic anhydride.Boron nitride(BN)particles with two average particle sizes(7.5μm and 757 nm)were used as filler to prepare two BN/epoxy resin composites.The possible bond cleavage of the crosslinking structural units of epoxy resin was investigated through density functional theory.The mechanical and thermal stability properties of the two BN/epoxy resin composites before and after gamma-ray irradiation under different absorbed doses were studied.The results showed that of all the chemical bonds consisting of a crosslinking structural unit,the C−C of the isopropyl unit had the minimum bond energy,making it easily breakable and leading to a breakdown of the polymer crosslinking network.When the absorbed dose exceeded 250 kGy,the tensile strength and thermal decomposition temperature of the epoxy resin and its composites noticeably decreased.The mechanical strength of the composite epoxy resins after irradiation depended on the combined effects of the BN particle size and the amount of added BN.When the absorbed dose reached 1100 kGy,n-BN/EP with a mass fraction of 3%exhibited the highest tensile strength and thermal decomposition temperature.Therefore,adding a small amount of submicron-sized h-BN can improve the radiation resistance of epoxy resin.This work has theoretical and practical significance for the development of radiation-resistant epoxy resin composites.