Effect of fluorination temperature on DC breakdown performance of bi-axially oriented polypropylene films
In order to improve the dielectric properties of bi-axially oriented polypropylene(BOPP)membrane,BOPP membranes were subjected to direct fluorination at 25 ℃,45 ℃,and 60 ℃ for 60 minutes.The direct current(DC)breakdown performances of the samples were studied through DC breakdown tests,and the surface physicochemical characteristics of the samples were characterized by attenuated total reflection infrared(ATR-IR)spectrum,X-ray photoelectron spectroscopy(XPS)analyses and scanning electron microscope(SEM)observation.The DC breakdown tests show that direct fluorinations at 25 ℃,45 ℃,and 60 ℃ increase the DC breakdown field intensities of BOPP films by 18.35％,22.75％,and 14.48％,respectively.The analysis of surface physicochemical characteristics shows that direct fluorination has changed the chemical composition and structure of the surface layer of BOPP membranes,forming a fluorinated layer that thickens with the increase of fluorination temperature.In addition,fluorination at a higher temperature of 60 ℃ has caused obvious micro-cracks on the surface of the sample.The improvement in breakdown performance is mainly due to the decrease in interface electric field or electrode charge injection caused by the fluorination,as well as the blocking effect of the fluorinated layer on charge entering into the sample.The micro-cracks on the specimen surface generated by the fluorination at higher temperatures have a negative impact on the charge blocking effect of the fluorinated layer.
bi-axially oriented polypropylenedirect fluorinationfluorination temperaturebreakdown field intensityfluorinated layerinterface electric fieldcharge blocking
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