LOW-TEMPERATURE GAMMA-RAY IRRADIATION EFFECTS OF POLYMER MATERIALS ON MECHANICAL PROPERTY

A low temperature gamma-ray irradiation equipment was constructed for the evaluation of the radiation resistance of polymer materials used in low temperature environment. The change of mechanical Property by irradiation at 77K was studied for glass fiber reinforced plastic (GFRP), poly(methyl methacrylate) (PMMA) and poly(tetra fluoroethylene) (PTFE), and compared with that by irradiation at room temperature. The decrease in flexural strength or in elongation at break showed a big difference between 77 K and room temperature irradiation. The ratio of dose at half strength or half elongation by 77 K and room temperature irradiation was 25 for GFRP, 17 for PMMA and 5 for PTFE. For GFRP the annealing effect at room temperature after irradiation at 77 K was observed scarcely by the flexural strength measurement at 77 K, which means that the degradation on mechanical property depends mainly on the temperature during irradiation.