Near-Ultraviolet Absorption Spectrum of Polyethylene

Abstract

The apparent absorption spectrum of polyethylene is studied between 1μ and the onset of true polymethylene absorption (described in the following paper) at 1780 Å. The apparent absorption is found to be caused by surface and Rayleigh scattering, by unsaturation in the polymer chains, and by a number of products of oxidation reactions some of which consist of polycyclic aromatic molecules. The aromatic compounds are at least partially responsible for the fluorescence, phosphorescence, and thermoluminescence of polyethylene, for its various chemical reactions under uv irradiation, and probably also for much of its electrical conductivity; the same may be true also for solid and liquid alkanes. A simple method is found for removing most of the oxidation products from polyethylene, so increasing its chemical purity and enabling the oxidation products themselves to be studied separately in solution.