Multiple enhancement of PVC cable insulation using functionalized SiO2 nanoparticles based nanocomposites

Manufacturing of a new insulation material for power cables has become necessary in order to withstand electrical and mechanical stresses. The current study aims to enhance the dielectric and mechanical properties of Polyvinyl Chloride (PVC), one of the wide used power cable insulation, by the insertion of chemically modified silica (silicon dioxide, SiO2) nanoparticles. The surface functionalization of the inserted SiO2 nanoparticles was performed using amino silane coupling agent, and the PVC/SiO2 nanocomposites were synthesized with different concentrations of nanoparticles. The surface morphology and chemical structure of the prepared samples were characterized by field emission scanning electron microscopy (FE-SEM) and Fourier transformation infrared spectroscopy (FT-IR). The mechanical properties of the obtained nanocomposites showed that the insertion of functionalized nanoparticles is able to increase the tensile strength and the Young's modulus of samples, however it decreases their elongation. In addition, the dielectric properties of PVC/SiO2 nanocomposites, such as relative permittivity (εr) and dielectric loss (tan δ), were also measured in a frequency range of 20 Hz-1 MHz. Moreover, AC breakdown voltage of the prepared samples was measured under uniform and non-uniform field, and AC dielectric strength was evaluated using finite element method (FEM) for non-uniform and uniform field. For further evaluation, DC dielectric strength was also measured under uniform field. The obtained data revealed that PVC/SiO2 nanocomposites with functionalized SiO2 nanoparticles exhibited better dielectric properties compared to that with un-functionalized one or that of neat PVC. The physical mechanisms behind the obtained enhancements have been discussed.