Electron microscopy of γ‐irradiated polyethylene

Abstract

In this paper, we have studied the structure and the phase transformations in thin films (obtained by evaporation from g-irradiated polyethylene bulks -ageing polymer) before and after laser irradiation. We made a comparison between the following samples: A -thin films obtained from g-irradiated polyethylene bulk and not subjected to laser irradiation; B -thin films obtained from g-irradiated polyethylene bulk and subjected to laser irradiation. We have revealed many modifications in the dielectric and structural properties of the thin films, depending on the dose, dose rate and the time of laser irradiation (in the case of samples B). The thickness of all deposited films was 90 nm. The samples (non-irradiated or irradiated) were analysed by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), in combination with selected area electron diffraction (SAED). We have also presented the structure of non-aged and non-irradiated thin polyethylene films (control polyethylene film), in which we observed a particularly puzzling phase between an incipient spherulitic phase and a fine structure of the spherulitic phase (specifically for thin PE films structure). After g-and laser irradiations, we observed a strong modification of the structure. The spherulitic phase was transformed. We observed large, amorphous, transparent crystals containing many defects, carbon precipitates, the beginning of crystallisation revealed by electron diffraction, treeing and breakdown figures (usually after laser irradiation).

The influence of orientation on the radiation-induced crosslinking/oxidative behavior of different PEs

“…1(g) and 2(c)). This increase has been manifested either through an increase in the size and height of initially existing craters or in the creation of some new hills and craters upon irradiation [37,38]. This can be explained by the formation of gaseous products during gamma radiolysis of PEs.…”