Stress-induced twinning and phase transformations in polyethylene single crystals

Abstract

A detailed study has been made of the deformation modes which operate in polyethylene single crystals when drawn on a Mylar substrate. The orientation relationships associated with the stress-induced twinning and monoclinic phase transformations have been determined by electron diffraction and compared with predictions based on recently developed theories of the crystallography of martensitic transformations. The agreement between theory and experiment is good and the identification of the deformation modes has enabled the criteria which govern the operation of these modes to be established. These criteria and the crystallography of the transformation processes are discussed in detail.