Radiation induced degradation of silica reinforced silicone foam: Experiments and modeling

We experimentally and theoretically investigate the effect of radiation on the mechanical behavior of silica reinforced silicone foam (SRSF). A series of uniaxial tension tests are performed for the gamma irradiated SRSF with γ-radiation dose from 0 to 600 kGy. The tensile modulus of SRSF increases with the increase of radiation dose, while the fracture strength and fracture strain generally decrease. Scanning electron microscope (SEM) observations of the fracture surface of SRSF show that the microporous structure of SRSF have not been changed for the γ-radiation up to 600 kGy. In other words, the alternation of mechanical properties mainly comes from the evolution of polymer network. So, a constitutive relation of irradiated SRSF is proposed by incorporating the radiation induced polymer network evolution, i.e. the evolution of the effective crosslink density and chain length, into the eight chain network model, which describes the experimental results very well. The methodology presented herein is also suitable for other polymers in radiation environment and beneficial to design high radiation resistant polymers for nuclear power plants and outer space structures.