In fields such as aerospace and nuclear energy, silicone rubber materials often face the test of extreme radiation environments, such as cosmic rays and high - energy particle radiation. In - depth research on the performance evolution laws and protection mechanisms of silicone rubber in extreme radiation environments is crucial for ensuring the safe operation of related equipment.

When silicone rubber is irradiated, the radiation energy interacts with the silicone rubber molecules, triggering a series of physical and chemical changes that lead to changes in its performance. In the low - dose radiation stage, radiation mainly induces cross - linking reactions of silicone rubber molecular chains. The free radicals generated by radiation promote the formation of new chemical bonds between molecular chains, and the cross - linking density gradually increases. To a certain extent, this process will increase the hardness and modulus of silicone rubber and improve the tensile strength. For example, in experiments simulating low - dose cosmic ray radiation, after a certain period of radiation, the hardness of silicone rubber samples increased by 10% - 20%, and the tensile strength increased by about 15%. However, as the radiation dose increases, the degradation reaction of molecular chains gradually dominates. High - energy radiation can break the silicon - oxygen bonds in the silicone rubber molecular chains, leading to molecular chain breakage and a decrease in molecular weight. At this time, the mechanical properties of silicone rubber decline sharply, manifested as a significant reduction in tensile strength and elongation at break, and the material becomes brittle and prone to fracture. When the radiation dose reaches a certain threshold, the elasticity of silicone rubber is lost, and it can no longer meet the requirements of practical applications.
To improve the performance stability of silicone rubber in extreme radiation environments, researchers have explored various protection mechanisms. Adding radiation protectants is a common and effective method. Radiation protectants can capture the free radicals generated by radiation and inhibit the degradation reaction of molecular chains. For example, some nitrogen - containing and sulfur - containing organic compounds are added to silicone rubber as radiation protectants. In a radiation environment, the active groups in these protectant molecules can quickly combine with free radicals, reducing the damage of free radicals to molecular chains. Experiments show that for silicone rubber with an appropriate amount of radiation protectants added, the retention rate of tensile strength under high - dose radiation is 30% - 40% higher than that of samples without protectants. In addition, by modifying the surface of silicone rubber, such as coating a radiation - shielding coating, the intrusion of radiation energy can be effectively blocked. Some coatings containing metal oxides (such as zinc oxide and titanium dioxide) can absorb and scatter radiation particles, reducing the impact of radiation on the internal molecular structure of silicone rubber. After coating such coatings on the surface of silicone rubber seals in nuclear facilities, their service life in a radiation environment is significantly extended, effectively ensuring the sealing and safety of the facilities.



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