Research On The Charged Characteristics Of Nanoparticles And Properties Of Polyethylene Nanocomposites

In recent years, the requirements for power system of high voltage directcurrent cable （HVDC） are increasingly critical accompanying with the rapiddevelopment of HVDC in domestic. Space charges can be effectively suppressedand the insulation properties and mechanical properties can be improved in theinsulator layer by mixing low density polyethylene （LDPE） with inorganicnanoparticles. The particularly important work is to choose different kinds ofnanoparticles to prepare the polyethylene nanocomposites with high dielectricproperties, it has become the focus of attention. Based on this, the paper focusedon the preparation of polyolefin nanocomposite latex with high dielectricproperties, the research on the relationships between charged characteristics ofinorganic nanoparticles and electrical characteristics and mechanical propertiesof polyethylene nanocomposite latex.The charged characteristics of inorganic nanoparticles are measured by Zetapotential. Given by the Zeta potential of nanoparticles, they were measured withthe ZetaProbe potential tester for the first time. They were measured in liquidparaffin owing to the similar structure between the liquid paraffin andpolyethylene. In the paper, four kinds of liquid paraffin suspension solutionswere made by four different kinds of nanoparticles.The results showed that Zeta potentials of nanoparticles modified bycoupling agent were larger than unmodified nanoparticles: Zeta potentials of fourkinds of50nm nano-SiO₂, nano-MgO, nano-TiO2and nano-BaTiO3particleswere-41.6mV,1.80mV,5.80mV,-0.67mV respectively. Zeta potentials of themodified nano-SiO₂, MgO, TiO2, and BaTiO3particles in the liquid paraffin are-53.40mV,10.12mV,6.40mV,6.59mV respectively. The results also revealed that The Zeta potentials were lower due to the increasing of the size of nano-SiO₂particles, their Zeta potentials were-68.40mV,-68.20mV,-53.40mVrespectively when the size of nano-SiO₂particles were at15nm,30nm,50nm.Zeta potentials indicted a decreasing trend after the first increase trend when thecontents of nano-SiO₂particles was increased, their zeta potentials were-58.30mV,-68.40mV,-36.40mV respectively when the contents of15nm-SiO₂particles was at1wt%,2wt%and3wt%.Comparing with the unmodified nanocomposites, the dispersion of thepolyethylene nanocomposites prepared by the four modified nanoparticles wasimproved, the electrical and mechanical properties are also improved to somedegree, while the changes of Zeta potential remained the same. The Zetapotential increases with the increment of the particle size of nano-SiO₂while theelectrical and mechanical properties of the polyethylene nanocompositesincreased. The Zeta potential showed a decreasing trend after the first increaseswhen the content of the nano-SiO₂was increased, the electrical and mechanicalproperties of the polyethylene nanocomposites increased.Polyethylene nanocomposites with optimum comprehensive performancewas obtained when the size of the SiO₂particle size is15nm and the content inpolyethylene is2wt%, and its tensile strength of13.9N/mm2, elongation atbreak of957.2%, work of fracture of14.3J, elastic modulus volume of116.3N/mm2, volume resistivity of20.8×1014·m, the breakdown field strength of30.73kV/mm.