Impact of the spatial distribution of high content of carbon nanotubes on the electrical conductivity of glass fiber fabrics/epoxy composites fabricated by RTM technique

To incorporate high content of carbon nanotubes (CNTs) into a polymer matrix is greatly desired to obtain highly conductive structural composites, but it is difficult in practice to be realized due to increased resin viscosity along with dispersion difficulty. In this study, we demonstrate the production of carbon nanotubes (CNTs)-integrated glass fiber fabrics (GFF)/epoxy composites by resin transfer molding (RTM), in which the mass fraction of CNTs on GFF varies from 0 to as high as 8 wt%. Three different methods were compared to load CNTs on GFFs, which include one-step in-situ CVD growth, catalyst pre-deposited two-step CVD growth and CNT suspension casting. For each type of CNTs-GFFs, a series of RTM composites with varied CNT contents were prepared. The impact of the CNT spatial distribution on the composite in-plane and through-plane electrical conductivities was compared at different CNT loading levels by subtracting contact resistance between the sample and the electrodes. It was found that the composites reinforced with one-step CVD-grown CNTs/GFFs show the best electrical conductivity among the three types of the composites studied, due to good CNT structure and their alignment on GF surface. A detailed discussion was made on the composite conductive behavior with the different CNTs-GFFs. This study helps to provide insight to the production of high-performance structural composites functionalized with high contents of CNTs at low cost.