Carbon-nanomaterial-filled polymer composites with controlled nanostructure for wide-area strain sensing

Abstract

This study investigates carbon-nanomaterial-filled-polymer composites as sensing materials by monitoring the electrical resistance of the sensors under flexural loading. Multi-walled carbon nanotubes (MWCNTs) and exfoliated graphite nanoplatelets (xGnPs) were used as conductive fillers. The use of electrical resistance has been explored for damage detection in CNT composite parts with promising results. This work focuses on MWCNT- and xGnP-polymer composite sensors as stand-alone devices that can be affixed, embedded or otherwise integrated into existing structures. The sensing performance was studied by bonding the sheet-type nanocomposite sensor to a substrate and subjecting it to three-point bending. In addition, nanocomposite sheets with mechanically aligned MWCNTs via extrusion were used as anisotropic strain sensors with pre-defined orientations that allow tailored sensitivity in different directions. Moreover, the effects of interfacial bonding between the carbon nanomaterials and the polymer matrix on piezoresistivity were investigated. Chemical functionalization of carbon nanomaterials occurred via acid treatment. The results suggest that the piezoresistive strain sensing performance can be tailored by controlling the nanostructure of composites by nanofiller alignment and nanofiller-polymer interface.