Strain Self-Sensing Tailoring in Functionalised Carbon Nanotubes/Epoxy Nanocomposites in Response to Electrical Resistance Change Measurement

Abstract

Carbon nanotubes (CNTs) are inherently multifunctional, conductive and possess piezo-resistive characteristics. Aiming at the multi-functionality of materials, nanocomposites made of epoxy resin with embedded CNTs are a promising solution for strain self-sensing applications. A critical parameter to achieve repeatable and reliable measure is the CNTs dispersion state in the resin. This study investigated the effect of CNTs concentration (0.01 wt% and 0.1 wt%), with different loading of surfactant Triton X-100, (0.0%, 0.2%, 0.5% and 1.0%) on strain sensing in terms of sensitivity and linearity based on electrical resistance data. The CNTs were synthesised directly using an injection floating catalyst chemical vapor deposition (ICCVD) process and their quality was characterised by Raman spectroscopy and scanning electron microscopy. Only the epoxy modfied with 0.1 wt% CNTs exhibited sufficient piezo-resistivity for the resistance measurements, and those with 0.01 wt% CNTs did not show sufficiently measurable conductivity so were excluded in our study, since their CNTs were highly entangled, and conductive network failed to be established. It was observed that, with 0.1 wt% CNTs, adding 0.5% content of the surfactant improved gauge factor. With more content of the surfactant (1.0 %), surprisingly, we observed a drop of gauge factor by the order of two. Therefore, by comparing the conductivity change between 1.0% and 0.5% surfactant, we postulated that the relatively high content surfactant has reached critical micelle concentration, and negatively affects CNTs dispersion state. The research presented in this article shows that moderate content of surfactant could improve piezoresistivity gauge factor while excessive surfactant could cause adverse effect.

Piezoresistive response of carbon nanotube and carbon fiber/epoxy composites under cyclic loading

“…One of the potentially viable options is the use of carbon nanotubes (CNTs) as a filler within the epoxy resin. 25,26 Multiwall carbon nanotubes (MWCNTs) have been commonly added to polymeric matrix to increase their mechanical performance and fatigue behaviour 27 as they exhibit outstanding mechanical, electrical and thermal performance which makes them promising filler for enhancing properties of a wide range of composite materials. 28…”

“…24 One of the potentially viable options is the use of carbon nanotubes (CNTs) as a filler within the epoxy resin. 25,26 Multiwall carbon nanotubes (MWCNTs) have been commonly added to polymeric matrix to increase their mechanical performance and fatigue behaviour 27 as they exhibit outstanding mechanical, electrical and thermal performance which makes them promising filler for enhancing properties of a wide range of composite materials. 28 The earliest studies focused on the changes in electrical resistance of only carbon fibers but not the polymer to monitor the strain change and growth of damage in the composite structure with constant loading as polymer is a non-conducive material.…”

Mechanical Strain Tailoring via Magnetic Field Assisted 3D Printing of Iron Particles Embedded Polymer Nanocomposites

“…Moreover, multi-material plastic wastes and functional materials are ideal candidates to promote sustainability even further beyond the status quo for remanufacturing and reuse in multifunctional composites. [1,[7][8][9] Despite having several advantages, such as improved design flexibility, reduced production time, and lower costs, there are significant challenges associated with achieving the desired geometric features in mould-less composite manufacturing. These challenges primarily arise from the manipulation of process parameters.…”