冷間圧延したPPの疲労特性に及ぼす応力振幅と環境温度の影響

抄録

Effects of the stress amplitude and the test temperature on the fatigue property of rolled PP under the room temperature and the low temperature have been examined according to the variation of dynamic visco-elasticity factor during the fatigue process. The result shows that the un-uniformity of material property in the specimen section is improved by rolling processing and the E'falls off while the tan δ rises. Therefore, the material becomes much ductile and the crack due to the fatigue is restrained. Although a tendency of ductile fatigue fracture is found with the increase of the stress amplitude under low rolling ratios less than 40% and the fatigue life becomes short, the specimen stretches uniformly without rupture corresponding to all stress levels under high rolling ratios more than 60%. As the molecule orientation becomes strong the elasticity and the strength properties are improved. Experimental results demonstrate that the rolled PP specimen has a fatigue resistance much superior to the unrolled PP specimen.