The scattering of light from thin polymer films. IV. Scattering from oriented polymers

Abstract

Abstract The scattering of both unpolarized and polarized light by a series of stretched polyethylene films has been studied. The radiation envelope of the scattered light loses its cylindrical symmetry upon stretching. The dissymmetry depends upon the orientation of the stretching direction of the film as does the intensity of scattered light. The results imply a scattering unit which is anisotropic both in shape and in polarizability. The largest dimension and highest polarizability lie in the stretching direction. The Debye‐Bueche theory has been generalized to describe oriented anisotropic systems. The single parameter, a , describing the size of the heterogeneity is replaced by two parameters, a and c . The mean‐square dielectric constant fluctuation η 2 depends upon the principal polarizabilities of the scattering unit and upon its orientation. The parameters are evaluated for the series of polyethylene samples. A model is proposed which accounts for the variation of the parameters as well as the changes occuring during melting and crystallizing the polymer.