Study on the effect of nano porous structure on the conductivity current of LDPE/SiO2 nano-composites

In order to study the influence of nanoparticles with porous structure on the dielectric properties of nanocomposites, two kinds of porous nano-SiO2 doped with LDPE composites materials and a common nano-SiO2 doped with LDPE composite material with different doping concentration were prepared. First, the porosity of the three types of nano-SiO2 was measured. It was found that the nano-SiO2 with the porous structure has larger specific surface area and more nano-pores. By measuring the crystallinity of the composite and observing with scanning electron microscopy (SEM), the results show that the crystallinity of the LDPE doped with nanoparticles have increased and the SEM micrographs show that the nanoparticles in all the samples were well dispersed. Conductivity current tests found that conductivity of composites decreased significantly compared to pure polyethylene and the conductivity of nano-SiO2 composite polyethylene with porous structure is lower, especially the surface-modified hydrophobic SiO2-doped composite has the lowest conductance. The doping of nanoparticles effectively increases the interfacial effect in the material, introducing more trap levels and trap densities which can capture charges, and this kind of phenomenon in nano-composite doped with nanoparticles with porous structures was even more pronounced. It can be assumed that the presence of nano-pores can effectively increase the number of traps to reduce the carrier mobility and reduce the conductance, which proves the influence of the nano-pore structure on the dielectric properties of the LDPE/SiO2 nano-composites, and the important role of special nanostructures in nano-dielectrics.