Effects of the amount and size of hexagonal boron nitride on the radiation resistance of silicone rubber

To enhance the radiation stability of silicone rubber (SR) and ensure its safe and reliable performance, hexagonal boron nitride (h-BN) was incorporated into SR as a functional filler. The effects of the filler amount and size on the mechanical properties, thermal stability, and radiation resistance of SR composites were investigated. The mechanism through which h-BN improved the radiation stability of SR was explored. The experimental results of stress-strain and hardness tests showed that the SR composite filled with 20 parts of h-BN (BN/SR-20) exhibited excellent mechanical properties. The tensile strength, 100% constant tensile stress (S100), and hardness of BN/SR-20 improved by 5.9%, 69.1%, and 15.6%, respectively, compared with those of unfilled SR (SR-U). BN/SR-20 displayed higher radiation resistance than SR-U, and its tensile strength and S100 were significantly better than those of SR-U in an ionizing-radiation environment. A larger transverse size of h-BN was found to be more effective in slowing down the radiation-aging process of SR. In addition, gas chromatography analysis of the radiolytic gas (hydrogen) yield and oxygen consumption of the composites and free-radical-scavenging experiments revealed that the addition of h-BN reduced the diffusion rate of O2 in SR and enhanced the radiation resistance of the composites.