The Relationship Between Dielectric Properties And Nanoparticle Dispersion Of Nano-Silica/Epoxy Composites

Nanoparticle/Epoxy composite materials are widely used in the field ofelectrical insulation. In this paper, we study the relationship between dielectricproperties and nano-particles dispersion and nano-particles contents ofnano-Silica/Epoxy composites. There are three kinds of preparation methods to madenamo composites, unmodified namo-Silica/Epoxy composites made by “mechanicalmixing method”, modified namo-Silica/Epoxy composites made by “mechanicalmixing method” and modified namo-Silica/Epoxy composites made by “bubblemixing method”. For each kind of preparation method, we make contents of2wt%、3wt%、4wt%、5wt%and6wt%nano-Silica composites. Quantify the dispersion ofnano-Silica in the namo composites. Test the dielectric spectrum characteristics,corona-resistance characteristics and breakdown strength of the three kinds ofnano-Silica/Epoxy composites.When the content of nano-Silica is at5wt%, we take the SEM images of thethree kinds of nano composites. The software Image J was used to statistics thenano-Silica particles dispersion informations and the Morisita’s Index was also usedto analyzed the nano-Silica particles dispersion. From the quantitativecharacterization dispersion of nano-Silica in the namo composites, we know the bestdispersion is modified namo-Silica/Epoxy composites made by “bubble mixingmethod”, the better dispersion is modified namo-Silica/Epoxy composites made by“mechanical mixing method”, and the worse dispersion is unmodifiednamo-Silica/Epoxy composites made by “mechanical mixing method”.In the dielectric properties text, we find the permittivity, the dielectric loss andthe breakdown strength of three kinds of namo-Silica/Epoxy composites are biggerthan pure Epoxy, the corona-resistance is better than pure Epoxy. With the nano-Silica loading, the permittivities and the breakdown strengths of three kinds ofnamo-Silica/Epoxy composites increase firstly, then reduce; the dielectric-lossesgradually increase; the corona-resistance characteristics enhance. We use thepercolation theory to explain the change of the breakdown strength with nano-Silicacontent.When the content of nano-Silica is at5wt%, the permittivity, the breakdownstrength and the corona-resistance characteristics of three kinds namo-Silica/Epoxycomposites enhance. Then we summarize the rules that the nano-Silica particles arebetter in dispersion, the permittivity, the breakdown strength and thecorona-resistance characteristics of namo-Silica/Epoxy composites will be better.