ORIENTATIONAL ORDER IN POLYETHYLENE FOILS - A POLARIZED RAMAN-SPECTROSCOPIC STUDY

Polarized Raman spectroscopy was used to determine the order parameters of the orientational distribution function for a series of stretched polyethylene foils with a relatively low degree of molecular orientational order. By combining measurements of the foil under study and of an isotropic polyethylene foil, simple backscattering experiments are sufficient to determine the orientation order parameters of the foil with molecular orientation. Practical considerations for obtaining polarized Raman spectra are discussed. The results are in good agreement with the order parameters obtained by IR dichroism and wide-angle x-ray diffraction. Differences between the various methods are discussed. The Raman method proves to be a relatively rapid method for obtaining information concerning the molecular orientation in polyethylene films.