Curing And Irradiation Effect Ofelectron Beam On Methyl Vinyl Silicone Rubber

On the background of the space application of silicone rubber, using a DD1.2 type high- frequency and high- voltage electron accelerator, it is studied on the cure by electron radiation, and the technology a nd mechanism of the modification by MQ silicone resin and Si O2 nano particles for methyl vinyl silicone rubber. The microstructure and property of the prepared materials were characterized based on many modern analysis methods.The electron radiation test shows that, the irradiation has a distinct curing effect on silicone rubber. The major mechanism of curing is the irradiation induced free radicals form three-dimension net structure through main chain growing and interstrand cross linking. The CASINO calculation illustrates that about 75% energy of 1Me V electron is lost in the 2mm- thick silicone rubber, which realizes the uniform curing. Within a certain irradiation fluence, the level of curing increased with increasing the fluence. The suitable irradiation fluence is determined as 1E14 e/cm2 according to the analysis on the measured results of mechanical property. The pure silicone rubber cured by electron beam shows excel ent optical property but lower strength and ductility.In order to further improve the property of the pure silicone rubber cured by electron beam, the modification was tried using MQ silicone resin and Si O2 nano particles. The analyses of cross link density, FTIR-ATR, and XPS shows that, the swelling and optical properties exhibit little change for the MQ SR silicone rubber with added 10 wt.% vinyl type of MQ silicone resin, while its mechanical and thermal stability properties are significantly increased. The main reason for that is the MQ silicone resin effectively promotes the chemical cross linking, resulting the three-dimension net structure is more easily formed. Due to the strong adsorptive act of Si O2 nano particles adding in MQ SR silicone rubber system, there is the interaction from hydrogen bond and/or Van der Waals’ force between the molecules of silicone rubber, leading to increase of cross link points and further improvement in the combination property of the system.Under the irradiation of 1Me V electrons, the properties of mechanics, thermal stability and optics are decreased with increasing fluence, while these properties show slight changes comparing to those of pure silicone rubber. It proves that the radiation resistance of the modified material is remarkably increased. The micro analysis indicates that, higher-fluence irradiation resulting in decrease of cross link density in the system, besides Si-OH bonds no formation of new bonds but showing decrease of content of each group and/or valence bonds, decrease in content of C, increase of content of O, Si with increase of the organic Si and decrease of the inorganic Si. It implies that the irradiation action is a combined process of cross linking and degradation while irradiation damage is mainly controlled by the degradation process.