Determination of Poisson's ratio and Young's modulus of low-density polyethylene

Abstract

The extensional moduli and Poisson's ratios of cold-drawn low-density polyethylene sheets have been determined by direct observation of the changes in dimensions under load of electron microscope grids printed on the surfaces of the sheets. The highly drawn sheets show incompressible behavior only for vanishingly small strains. It is proposed that the departure from incompressibility is associated with the departure from linear deformation. It is suggested that the anisotropic behavior can be analyzed in terms of three deformation mechanisms: (a) the c-shear mechanism; (b) incompressible elastic deformation associated with the amorphous regions; and (c) a slip mechanism which produces the departure from linear deformation.