Tensile Deformation of Oriented Polyethylene

Tensile test specimens have been cut from high-density polyethylene sheet which had been fully cold-drawn. The angle between the tensile axis and the draw direction was varied from 30° to 75°. The tensile deformation of such specimens was analyzed with the aid of a grid printing technique and was shown to be predominantly simple shear in the molecular chain direction. However, detailed analysis has shown that associated with the simple shear process there was a reorientation of the material, which is compared with the predictions of an aggregate theory for oriented polyethylene. A yield criterion and the absence of any work hardening for large deformations have been established.