Study of tensile properties of multiwalled carbon nanotube/polyether ether ketone polymer composites at the nanoscale

Abstract

This study demonstrates the microscale and nanoscale mechanical properties of a multiwalled carbon nanotubes/ polyether ether ketone (MWCNTs/PEEK) composite utilizing a novel in situ testing method. Nanoscale testing specimens of a composite of PEEK thin film dispersed with 6.5 wt% MWCNTs were successfully prepared using focused ion beam (FIB) and investigated by a tensile testing device accommodated inside a field emission scanning electron microscope. The average tensile strength of the nanocomposite was measured to be 388.66 MPa. The average Young's modulus measured at 6.52 GPa demonstrated a 23% increase compared to that of the bulk specimen, suggesting a sizedependent mechanism that limits the plastic deformation of the microscale specimens possibly due to the limited defects distribution and motion constraint of the polymer chain in the small specimen and the amorphous regions of the PEEK matrix.

Carbon nanotube/polyetheretherketone nanocomposites: mechanical, thermal, and electrical properties

“…Ashby plot. [79][80][81][84][85][86]89,93,94 Overall, the presence of CNTs can increase the elastic modulus E remarkably, while the increase in ultimate tensile strength r uts is still limited due to various problems. For example, the direct extrusion mixing can hardly result in a uniform distribution of CNTs among PEEK matrix, and thus the strengthening was still limited even at a high CNT fraction, as reported by Deng et al 85 When the fraction was up to 15 wt%, r uts was just increased from 93.55 to 110.90 MPa, by just 18.5%, whereas E was increased from 4.0 to 7.55 GPa, by 88.8%.…”

“…For the sandwich-like CNT film/PEEK composites, r uts and E were improved from 113.2 MPa and 2.67 GPa to 118.2 and 3.73 GPa, respectively. 89 In order to find out the upper limit of CNT reinforcement, Hsu et al 94 designed an in situ tensile testing inside a scanning electron microscope (SEM) on which dog-bone specimens with dimensions of 20 mm  4 mm  $800 nm were tested. From the stress-strain curves (Figure 2(d)), it is found that these samples were much stronger than and as stiff as the macroscopic samples, with r uts ¼ 369-417 MPa and E ¼ 5.99-7.36 GPa.…”

“…Figure 2(a) summarizes the recent development of CNT/PEEK nanocomposites by plotting the strength-modulusAshby plot [79][80][81][84][85][86]89,93,94. Overall, the presence of CNTs can increase the elastic modulus E remarkably, while the increase in ultimate tensile strength r uts is still limited due to various problems.…”

“…(c) Tensile stress-strain curves for PEEK composites reinforced by different CNTs 81. (d,e) A small-scale in situ tensile testing on CNT/PEEK composites 94. The stress-strain curves (d) indicate a strength up to 369-417 MPa, and the deformation process (e) shows clear CNT pulls-out at the fracture.…”

Morphology and properties of foamed high crystallinityPEEKprepared by high temperature thermally induced phase separation

“…PEEK adheres well to carbon fibers, 8 carbon nanotubes 9 and other fillers, 10 which can be used to further improve the mechanical and thermal properties of PEEK. PEEK and reinforced PEEK are widely used in biomedical applications as artificial scaffolds 11 or as implants without requiring any additional coatings or modifications because of their bioinert nature 12,13 .…”