Self-Monitoring Performance of 3D-Printed Poly-Ether-Ether-Ketone Carbon Nanotube Composites

Abstract

In this paper, poly-ether-ether-ketone (PEEK) carbon-nanotube (CNT) self-monitoring composites at different levels of filler loading (i.e., 3, 5 and 10% by weight) have been extruded as 3D-printable filaments, showing gauge factor values of 14.5, 3.36 and 1.99, respectively. CNT composite filaments of 3 and 5 wt% were 3D-printed into tensile samples, while the PEEK 10CNT filament was found to be barely printable. The 3D-printed PEEK 3CNT and PEEK 5CNT composites presented piezo-resistive behavior, with an increase in electrical resistance under mechanical stress, and showed an average gauge factor of 4.46 and 2.03, respectively. Mechanical tests highlighted that 3D-printed samples have a laminate-like behavior, presenting ultimate tensile strength that is always higher than 60 MPa, hence they offer the possibility to detect damages in an orthogonal direction to the applied load wit high sensitivity.

High-Performance PEEK/MWCNT Nanocomposites: Combining Enhanced Electrical Conductivity and Nanotube Dispersion

“…The electrical percolation threshold measured for PEEK/MWCNT nanocomposites in Figure 2 is within the range reported in the literature for PEEK nanocomposites [ 15 , 20 , 21 , 22 , 23 , 24 , 27 , 28 , 29 ]; an electrical percolation threshold between 1 and 3 wt.% of MWCNT is typically reported. With the incorporation of 1 to 4 wt.% MWCNT in the PEEK nanocomposites, the electrical conductivity levels attained allow electrostatic discharge applications, applications in the semiconductor range and, for the nanocomposites produced with >4 wt.% MWCNT, shielding applications (>10 −2 S/cm) [ 13 , 18 , 48 ].…”

“…From 1 to 2 wt.%, a percolation threshold is reached with electrical conductivity varying from 1.59 × 10 −7 to 2.34 × 10 −2 S/cm. An interconnected network of MWCNT, comprising individual MWCNTs and agglomerates, was formed at this loading [ 16 , 22 , 26 ].…”

“…Thermoplastic composites usually present an electrical percolation threshold at around 0.05–5 wt.% CNT [ 15 , 20 , 21 , 22 , 23 ]. PEEK–CNT composites produced via various techniques have been reported to present a percolation threshold in the range of 1 to 5 wt.% CNT, in applications such as high-performance EMI shielding and electrostatic discharge materials for advanced technologies [ 22 ].…”

“…Thermoplastic composites usually present an electrical percolation threshold at around 0.05–5 wt.% CNT [ 15 , 20 , 21 , 22 , 23 ]. PEEK–CNT composites produced via various techniques have been reported to present a percolation threshold in the range of 1 to 5 wt.% CNT, in applications such as high-performance EMI shielding and electrostatic discharge materials for advanced technologies [ 22 ]. Although there are many publications dealing with the electrical percolation threshold for polymer/CNT composites [ 12 , 16 , 18 , 24 , 25 ] produced by melt processing, only a limited number of publications report on PEEK/CNT composites [ 20 , 21 , 26 , 27 , 28 , 29 ].…”

Tunable afterglow for mechanical self-monitoring 3D printing structures

“…Currently, the most commonly used self-monitoring materials are piezoresistive composites, which are usually achieved by adding conductive materials to polymer matrices, i.e ., carbon fibres 45 , 46 , graphene oxide 47 and reduced graphene oxide 48 and carbon nanotubes 49 . The deformation of composites may lead to changes in the filler and conductive network and further increase the resistivity 50 . However, it still requires an external device as an auxiliary to detect the change, and the failure location is also difficult to accurately locate.…”