LOW-TEMPERATURE GAMMA-RAY IRRADIATION EFFECTS OF POLYMER MATERIALS ONMECHANICAL PROPERTY

A low temperature gamma-ray irradiation equipment was constructed for the evaluation of the radiation resistance of polymer materials used i n low temperature environment. The change of mechanical Property by ir radiation at 77K was studied for glass fiber reinforced plastic (GFRP) , poly(methyl methacrylate) (PMMA) and poly(tetra fluoroethylene) (PTF E), and compared with that by irradiation at room temperature. The dec rease in flexural strength or in elongation at break showed a big diff erence between 77 K and room temperature irradiation. The ratio of dos e at half strength or half elongation by 77 K and room temperature irr adiation was 25 for GFRP, 17 for PMMA and 5 for PTFE. For GFRP the ann ealing effect at room temperature after irradiation at 77 K was observ ed scarcely by the flexural strength measurement at 77 K, which means that the degradation on mechanical property depends mainly on the temp erature during irradiation.