EFFECT OF MGO NANOPARTICLES ON THE MECHANICAL, THERMAL AND ELECTRICAL PROPERTIES OF LINEAR LOW DENSITY POLYETHYLENE (LLDPE) NANOCOMPOSITES FOR CABLE APPLICATION

Abstract

This study discusses with development of insulating materials for High Voltage Direct Current (HVDC) cable insulations by reinforcing nanomagnesia (MgO) particles with linear low-density polyethylene (LLDPE). The main work is to investigate the DC breakdown voltage performance of LLDPE/MgO nanocomposites as a function of filler. Increase in DC breakdown strength is very important for long-term reliability and safety of HVDC cable insulation. Besides electrical performance, tensile strength, thermal and morphological studies were made as complementary studies to check the mechanical, thermal stability and quality of particle dispersion. The LLDPE/MgO nanocomposites were prepared by melt blending technique with different ratios of MgO nanoparticles. A modifier was used to reduce the agglomeration of MgO nanoparticles inside the LLDPE matrix. DC breakdown voltage tests were conducted on the samples to determine their breakdown voltage. Improvements have been observed in tensile strength (23%), flexural strength (21.5%), impact strength (15.6%), thermal stability (35.42 °C), dielectric breakdown strength (48%) and melting point (3.4 °C) of 6 wt% MgO nanocomposites compare to neat LLDPE. Field Emission Scanning Electron Microscopy (FESEM) was undertaken to complement the results, which included the dispersion quality of MgO particles and the filler interfacial bonding. Results indicated that nanomagnesia incorporation improved the DC breakdown voltage of LLDPE, with the optimum value of 6 wt% MgO. At this loading, the material showed the strongest dielectric strength while retaining reasonable tensile properties. Thus, this study has proven that LLDPE reinforced with 6 wt% nanomagnesia is a viable and efficient insulation material for HVDC cable applications.