Effect of Hybrid Fillers on GFRP Epoxy Composites with Water Immersion and Thermal Conditioning

Abstract

AbstractGlass fiber reinforced epoxy composite with graphene nanoplatelets, multi‐walled carbon nanotubes, and aluminium trihydrate fillers are fabricated by the pultrusion method. The role of fillers in complementing each other, improving the dielectric properties of the epoxy matrix is not fully understood. The objective of this work is to investigate the effects of nano and micro fillers combination by short‐duration laboratory ageing techniques. A comparison of aged and unaged specimen is carried‐out by impedance spectroscopy and gravimetric analyses. The dielectric properties are observed to be dependent on the interaction between the fillers and the epoxy matrix, also on the relative permittivity of individual nanofillers, dissolved ions that diffuse with water into the bulk of the composites. The composite specimens are immersed in distilled water up to 360 h for water ageing and the temperature is varied from 25 °C to 200 °C for thermal ageing. The impedance spectroscopy of the composites is measured over the frequency range (10 Hz–8 MHz). The observed reduction in the impedance values indicate that dipolar polarization is occurring due to absorbed water molecules during water immersion and mobilization of free electrons is taking place due to an increase in temperature. This study indicates that the effect of ageing can be quantified in terms of changes in the impedance spectra. From the results obtained, the effect of fillers is implicit since diffusion coefficient values are reduced from 5.58 × 10−9 m2 s−1 of the base epoxy composite to 3.48 × 10−9 m2 s−1 in hybrid nanocomposites. The percentage of water absorption at equilibrium condition is reduced from 0.68% to 0.46% of the total mass.