Electron induced modifications in the optical properties of polypropylene

In this work, the effect of electron beam (EB) irradiation on polypropylene (PP) films has been studied via different techniques, namely: x-ray diffraction and UV-Vis absorption spectroscopy. The PP films were irradiated with a 1.5 MeV electron beam at doses of 5, 10, 20, 50, 70, 100 and 120 kGy. The crystallinity of the PP films was found to increase, slightly, by EB irradiation. The changes in the dipole strength, transition dipole moment, oscillator strength, optical band energy gap and activation energy have been investigated as a function of the irradiation dose. The results exhibited an increase in both the dipole moment and the oscillator strength; meanwhile, a decrease was found in both the energy gap and the activation energy with increasing dose. The obtained results explored a linear relation plotted between each of the dipole moment, the oscillator strength and the activation energy and the irradiation dose that showed good correlation coefficients. The results suggest the possible use of this polymer as a dosimeter for electron beams in the dose range of interest (0-120 kGy) by means of UV-Vis spectrophotometry.