Performance investigation of hydrothermally stressed polyamide nanocomposites for insulation applications

Abstract

This paper investigates the performance of novel nano ZnO filled polyamide nanocomposites under hydrothermal conditions for cable insulation applications. Neat polyamide (PA0) and its nanocomposite with 0wt.% (PA0), 1 wt.% (PA1), 3 wt.% (PA3), 5 wt.% (PA5), and 7 wt.% (PA7) of nano ZnO were prepared and subjected to accelerated hydrothermal aging conditions in a programmable chamber at 85 oC and 85% relative humidity for 300 hours. The samples were analyzed with visual inspection, hydrophobicity evaluation, optical microscopy, Fourier Transform Infrared (FTIR) spectroscopy, leakage current and UV-Vis spectroscopy after every 100 hours of aging. Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) were employed for analyzing filler dispersion. Maximum filler dispersion was achieved in the case of 3wt.% of nanofiller. All the samples expressed surface degradation and increase in leakage current after aging. Maximum surface roughness and highest leakage current of 7µA were noticed for PA0, however PA3 expressed lowest leakage current and surface degradation. PA0 expressed the lowest hydrophobicity class of HC-3 and lowest contact angle of 75o after aging. Among the nanocomposites, PA3 expressed the highest hydrophobicity class (HC-1) and contact angle (112o) after aging. FTIR results expressed that all the samples suffered from oxidation and the C=O peaks at ~1728cm-1 increased by 120%, 100% and 120% for PA1, PA3 and PA7 respectively. The peaks of -OH group at ~3500cm-1 increased for all the sample indicating moister absorption. However, it is observed that the addition of nanofiller enhanced the overall performance of composites and among the composites PA3 performed better.