1991 年 19 巻 2 号 p. 72-75
The high-density polyethylene (HDPE) films have been prepared either through melt quenching or isothermal crystallization. The fatigue behavior of those HDPE films under constant strain amplitude has been investigated based on dynamic viscoelastic and small angle light scattering (SALS) measurements during the fatigue process. Non-linear viscoelastic behavior under cyclic fatigue has been observed for both melt quenched and isothermally crystallized HDPE's. Melt quenched HDPE showed greater fatigue strength compared with isothermally crystallized HDPE. The SALS measurement under cyclic fatigue can reveal the deformation process of spherulitic structure during the fatigue process. Melt quenched HDPE showed elongation of spherulitic structure under cyclic fatigue. On the other hand, isothermally crystallized HDPE didn't show any elongation until the onset of fatigue fracture. The short fatigue lifetime and small deformation of spherulitic structure for isothermally crystallized HDPE can be ascribed to the sharp boundary between spherulitis.