OPTICAL-PROPERTIES OF GAMMA-IRRADIATED LOW-DENSITY POLYETHYLENE

A detailed study of the optical absorption as a function of the sample thickness and gamma-irradiation dose for low-density polyethylene (LD PE) is presented. Samples of thickness from 0.02 to 2.0 cm were prepar ed. The optical absorption spectra were measured in the wavelength ran ge from 200 to 1100 nm at integrated gamma-doses from 1 to 300 Mrad. T he calculated absorption coefficient, absorption index and the determi ned values of energy gaps (E(opt)) and DELTAE) were found to be gamma- irradiation dependent. For thicknesses up to 0.5 cm, parameters such a s absorption edge, E(opt) and DELTAE can be readily determined. Beyond 0.5 cm thickness it was not possible to determine these parameters. T he results indicated that, for LDPE, the validity of the Urbach rule d epends on the sample thickness and the irradiation dose.