Anisotropy of viscoelastic relaxation in low-density polyethylene in terms of an aggregate model

Abstract

The aggregate model for mechanical elastic anisotropy of oriented polymers is extended to a viscoelastic polymer in which one shear modulus is complex. It is shown that this model predicts the anisotropy of the α relaxation in cold-drawn sheets of low-density polyethylene. This anisotropy relates to the orientation of the crystalline regions of the polymer, determined by wide-angle X-ray diffraction and nuclear magnetic resonance. It is, therefore, concluded that the α relaxation in low-density polyethylene is activated by shear in the c direction in planes containing the c-axis.