Effects of irradiation and rolling on the tensile behavior of polyethylene

Tensile properties of low‐pressure polyethylene subjected to both irradiation and rolling have been studied. Co 60 was used as the γ‐ray source. The anisotropic properties induced by rolling and irradiation were measured by testing the tensile behavior of specimens cut at 0°, 45°, and 90° to the direction of rolling. The yield strengths of specimens cut parallel to the direction of rolling increased with increasing reduction in thickness, but the yield strengths of those cut at 45° and 90° were scarcely affected. The yield strengths of specimens that were irradiated, or irradiated and rolled, increased doses, and then decreased with increasing irradiation, regardless of whether the specimens were irradiated after rolling or rolled after irradiation. The final elongations of the specimens that were irradiated after rolling and cut parallel to the direction of rolling decreased slowly with increasing irradiation, but those of the specimens cut at right angles to the direction of rolling decreased very rapidly. In contrast, the final elongations of all specimens that were rolled after irradiation decreased very slowly regardless of the cutting direction. It may be concluded from the experimental results that the tensile properties of polyethylene irradiated after rolling are more anisotropic than those of the polyethylene rolled after irradiation.