Understanding the thermal ageing performance of epoxy aluminium nitride nanocomposites through space charge studies and by LIBS analysis

Abstract

Epoxy aluminium nitride (AlN) nanocomposites were prepared to understand the influence of thermal ageing on dielectric and space charge performance of the material. It is observed that the real relative permittivity values of epoxy AlN nanocomposites are higher than epoxy resin when wt% of AlN is >1 wt%. Also, the epoxy AlN nanocomposites depicted an increase in dielectric loss compared to the neat epoxy specimen. The space charge variations in the test specimens are analysed by adopting a pulse electro-acoustic technique. It is observed that the nanocomposites have lesser space charge in the bulk volume of insulating material compared with pure epoxy resin. Also, it is realised that the local electric field is less with nanocomposite material in both virgin and thermally aged specimens. The threshold electric field is observed to be lesser with epoxy resin compared to nanocomposites. Laser-induced breakdown spectroscopy (LIBS) analysis clearly indicates the reduction in plasma temperature with epoxy AlN nanocomposites compared to pure epoxy resin. Principle component analysis (PCA) has classified the nanocomposite materials having different filler concentrations from the pure epoxy resin, qualitatively based on their LIBS spectra. Thermally aged epoxy AlN nanocomposites are successfully classified from unaged nanocomposite specimens, using PCA.