Oblique Strain Markings in Oriented Polymers

Abstract

A brief review of the literature on strain markings is followed by a discussion of additional experiments showing the effects of pretreatment and environment on the occurrence of oblique strain marks in poly(ethylene terephthalate) fibers in terms of the implications of these effects on models of polymer fine structure. Oblique strain marks are concluded to be abrupt shear deformations commonly known as Lüders' lines, occurring mainly in compression in a manner analogous to neck formation in tension. The details of their formation are inconsistent with a metallurgical analogy for polymer deformation. The morphology of these markings is discussed and compared with transverse strain markings which often accompany tensile strains.