Amorphous Phase Properties Of Oriented Polyethylene Solids

Abstract

Solid-state deformation of polyethylene results in a preferential orientation of both crystalline and amorphous regions. Usually, one major problem in the prediction of the mechanical and thermal expansion properties of anisotropic polyethylene lies in determining values for the amorphous phase properties and, particularly, at a given level of solid-state deformation. This paper outlines simple procedures for determining the two-dimensional amorphous orientation function and values for the mechanical and thermal expansion properties of the oriented amorphous phase. Mathematical expressions for determining the tensile and shear moduli, Poisson ratio and thermal strain of the amorphous phase for anisotropic polyethylene at any level of orientation are defined. Comparison between the predicted amorphous phase tensile modulus and the experimental measurements yields an agreement within 30%.