Tuning dielectric response of polyethylene by low gamma dose: Molecular mobility study improvement by dipolar probes implementation

Abstract

Dynamic Dielectric Spectroscopy is a powerful method to study the molecular mobility of dipolar polymers. As Linear Low Density Polyethylene is globally non polar, the dielectric experimental signal needs to be seriously improved. The aim of this study is to implement carbonyl groups by gamma irradiation, that act as dipolar probes in order to increase the signal to noise ratio. A specific attention is paid to induce as less modification as possible. Films were gamma irradiated in dioxygen media with different absorbed doses from 0 kGy to 100 kGy. After irradiation, better signal to noise ratios have been obtain thanks to polar probes introduction. The study of dielectric relaxation modes is then possible, extended and much more precise. One should irradiate the polymer with the lowest dose, between 12.5 kGy and 25 kGy, to obtain satisfactory Dynamic Dielectric Spectroscopy results with virtually no chemical and physical changes in the gamma irradiated samples.