Abstract
Plastic deformation processes in oriented polyethylene are investigated by the X-ray method, and changes in texture produced by transverse compression are interpreted in terms of twinning, slip and phase transformation. The crystal structure of the new form produced by the phase transformation is determined, and the unit cell is a monoclinic one with a=8.09, b=2.53, c=4.79 Å and β=107.9°. The phase transformation is considered to be of diffusion-less type and a transition mechanism similar to that of twinning is proposed.