抄録
Degradation of polystyrene caused by dynamic fatigue combined with irradiation of ultraviolet rays is here under reported.
The fatigue behavior during the fatigue test, i. e. the dynamic deflection and temperature rises of the specimens, were also observed with the method as was reported in the previous paper.3) The degradation was determined by infrared and ultraviolet spectroscopy, X-ray diffraction, differential thermal analysis, thermogravimetric analysis and solution viscosity. The fatigue testing machine used here was the modified one of ASTM D-671-63T method B. The specimens were made of G. P. grade polystyrene by injection for the ASTM type. The condition of the sample prepapation are as follows: original, irradiation only of ultraviolet rays (48, 167hrs), fatigue only (48, 167hrs), irradiation (48, 167hrs) followed by fatigue (48, 167hrs) and irradiating fatigue (48, 167hrs), their alternating loads being 2.5kg for 48hrs and 1.6kg for 167hrs.
The results of the experiment show that for G. P. polystyrene, the degradation caused by the dynamic fatigue and the irradiation of ultraviolet rays are not remarkable, though photo-oxidation is observed in the case of polystyrene film, and so the photo-degradation may be limited to the specimen surface. As to the fatigue behavior of polystyrene, the dynamic deflection change was small and this phenomenon agrees with the small degradation observed in the present experiment.
