Effect of Negatively Charged SiO2-PMMA Filler on Properties of Epoxy Resin Composites

The electrical properties of epoxy resin (EP) composites are closely related to the dispersibility of their fillers. Nanoparticles have a large specific surface area and are prone to agglomeration, which prevents them from taking advantage of their advantages. In order to reduce the agglomeration of nanoparticles, a composite filler with charged encapsulation structure was prepared in this paper by choosing polymethyl methacrylate (PMMA) as the core and nano-SiO
2
as the shell. The SiO
2
was uniformly coated on the negatively charged PMMA by a one-step method, and the dispersed SiO
2
-PMMA microspheres were obtained according to the principle of mutual repulsion of homogeneous charges, which prevented the agglomeration of nano-SiO
2
in the epoxy resin matrix. The breakdown strength, dielectric constant, dielectric loss, volume resistivity and bulk resistivity of the SiO
2
-PMMA/EP composites were measured, which showed different degrees of improvement compared with pure EP and SiO
2
/EP composites.