Effect of Gamma Irradiation on the Dielectric Properties and X-Ray Phase Analysis of the Polypropylene Na+Montmorillonite Composite

Effect of γ-irradiation on the dielectric properties of polymer composites based on polypropylene (PP) with Na+-montmorillonite (MMT) nanoparticles has been investigated. It has been found that γ-irradiation in the dose range of 100-200 kGy leads to slight deterioration in the dependences of ε = f(T) (a) and tgδ = f(T) of the polypropylene-based composite with Na+MMT filler. Further increasing the radiation dose, a sharp increase in ε and tgδ above the temperature ~ 440 K has been observed. The obtained results show that after irradiation, the active centers, radicals, and defects formed in the polymer structure interact with filler nanoparticles, reducing the mobility of the polymer chain and consequently decreasing the values of ε and tagδ of the composite. But at an irradiation dose of 300 kGy, the properties of the interphase layer deteriorate as a result of incipient destruction, which leads to an insignificant increase in the values of ε and tgδ. The results of the analyses showed that the introduction of Na nanoclays (MMT) into polypropylene in an amount of 0.5% by volume leads to some improvement in the dielectric properties before and after irradiation. It is assumed that the deterioration of the dielectric properties during irradiation in composites occurs due to changes in the crosslinking and destruction processes in the polymer matrix and at the polymer-filler interphase boundary. It is shown that due to γ-irradiation of polymer composites, it is possible to expediently control its dielectric and electrophysical properties.