What is Mechanism of Space Charge Accumulation in Polyethylene with Surface Fluorination?

Several researches has proved that surface fluorination of polyethylene has a significant barrier effect of space charge, so whether the surface fluorination treatment of poly (ethylene-co-vinyl acetate) (EVA) loaded with carbon black particles electrode has the same effect? In this study, the space charge distribution in polyethylene under different electrode fluorination conditions was measured with laser-PWP method to observe the blocking effect of surface fluorination. Experimental results show that the homo space charge distribution inside the polyethylene heat-pressed with fluorinated electrode increases, which is exactly the opposite of the situation of surface fluorination of polyethylene. ATR-IR spectra reveal that a fluorinated layer is formed on the surface of the fluorinated electrode, which blocked the impurities from diffusing into the polyethylene. The surface fluorination of EVA+CB electrode may have the effect of blocking the diffusion of impurities, instead of suppressing the charge injection. While the homocharge injection from electrode unchanged and the heterocharge generated by impurities reduces, the measured charge in the apparent result is greatly increased. And the fluorinated layer on polyethylene blocks both impurities and carbon black particles, resulting in a significant reduction in the total charge distribution.