The effect of crystallite orientation on mechanical anisotropy in low-density polyethylene

We have recently studied the anisotropy of tensile modulus in cold-drawn low-density polyethylene films over the temperature range −125 to 60°C [l]. The pattern of anisotropy has been explained by a theoretical model [2] in which the polymer is regarded a s an aggregate of anisotropic units whose properties are those of the most highly oriented film. The compliances of this aggregate in the draw direction S33 and perpendicular to the draw direction S33 , using the Reuss scheme for averaging, are given by the following relationships.