抄録
Among many other uses, rubber is used in tubes and wire covers. Rubber exhibits considerable changes in mechanical properties over time and in temperature. To confirm the reliability of these products, we must evaluate how they degrade in humidity, sunlight, and under thermal loading. We therefore studied the thermal degradation of chlorosulfonated polyethylene rubber (CSM) and ethylene propylene diene methylene linkage (EPDM). We first measured thermal reduction of elongation and of fatigue strength of CSM and EPDM. To evaluate the degrading of these properties, we used Arrhenius's equation to confirm the relationship between temperature and exposure time. Using these evaluation methods we could predict thermal reduction of fatigue strength by taking into account the temperature and exposure time. The acceleration in thermal degradation of elongation and that of fatigue strength agreed well quantitatively. We next measured the viscoelastic behavior of virgin CSM and EPDM material and of thermally degraded material. We evaluated the thermal degradation of mechanical loss tangent by using Arrhenius's equation to confirm the relationship between the temperature and the time. The acceleration in thermal degradation of a mechanical loss tangent was in good agreement with the acceleration in thermal degradation of elongation and of fatigue strength.
