Effects Of Preparation Process Of Nano SiO₂/LDPE Composites On Dielectric Properties Of Materials

Low density polyethylene(LDPE) nanocomposite materials are widely usedin the field of electrical insulation. Study has shown that LDPE is used as matrix,adding the appropriate amount of nanoparticle powder as additive, improveelectrical endurance properties of the composite materials effectively, But addingnanoparticles powder dispersed in polymer matrix differently, have differentinfluence on electrical endurance properties of the composites.In order to study the dispersity of nano-silica particles in low densitypolyethylene matrix on the effects of composite materials electrical propertiesand improve the electrical properties of the polymer, the surface state ofuntreated nano-silica and nano-silica powder with suitable surface treatment isanalyzed by this article. Nano-silica untreated and nano-silica with suitablesurface treatment is selected as inorganic filler, low density polyethylene selectedas matrix resin, three kinds of mixer methods used to prepare1wt%nano-silicacomposites through a twin-screw extruder, an open mill machine and internalmixer machine, making quantitative characterization of nano-silica particlesdispersity, and space charge, breakdown characteristics, conductivity temperaturecharacteristics and dielectric spectroscopy of nano-silica composites is tested.Combining with SEM images of the nano silica/LDPE composites by threepreparation methods and using ImageJ software to extracte feature datas of nano-silica particles, and using Morishita’s index with math statistics method toanalyze the dispersity of nano-silica particles, the results show that dispersity ofmodified nano-silica/LDPE composites by open mill machine preparation is best,dispersity of modified nano-silica/LDPE composites by twin-screw extruderpreparation is second, dispersity of unmodified nano-silica/LDPE composite by internal mixer is worst. By testing breakdown field strength of composites andcombining with the shape parameter of Weibull distribution to representdispersity of nano-silica. Results is identical with statistical results of scanningelectron microscopy image.For1wt%nano-silica content, the space charge of modified and unmodifiednano-composite is suppressed, conductivity currents decreased and permittivityincreased than pure LDPE. Combining with result of quantitative characterizationof nano dispersity shows that the better dispersity of nanoparticles, the less spacecharge of nanocomposite.