Study on positron annihilation lifetime spectrum of polysilicone rubber after proton radiation

The positron annihilation lifeti me spectrum(PALS) method was employed to study the effect of proton radiation on microstructure of the space grade KH-L-Y polysilicone rubber. The results show that both t 3, and I3 of the longest lifetime component and the free volume Vf decrease with the increase of the radiation fluence at the beginning and become level off after 1015cm- 2 radiation fluence. The proton radiation causes decrease in both the free volume of polysilicone rubber, and the distance between the molecules when the radiation fluence is less than 1015cm- 2. However, the proton radiation makes the free volume of silicon rubber increase when the radiation fluence is greater than 1015cm- 2. Both the experimental results of the cross-linking density and DMA indicate that the cross-link