Tensile Characterization of Single-Walled Carbon Nanotubes with Helical Structural Defects

Abstract

Recently, evidence was presented that certain single-walled carbon nanotubes (SWNTs) possess helical defective traces, exhibiting distinct cleaved lines, yet their mechanical characterization remains a challenge. On the basis of the spiral growth model of SWNTs, here we present atomic details of helical defects and investigate how the tensile behaviors of SWNTs change with their presence using molecular dynamics simulations. SWNTs have exhibited substantially lower tensile strength and strain than theoretical results obtained from a seamless tubular structure, whose physical origin cannot be explained either by any known SWNT defects so far. We find that this long-lasting puzzle could be explained by assuming helical defects in SWNTs, exhibiting excellent agreement with experimental observation. The mechanism of this tensile process is elucidated by analyzing atomic stress distribution and evolution, and the effects of the chirality and diameter of SWNTs on this phenomenon are examined based on linear elastic fracture mechanics. This work contributes significantly to our understanding of the growth mechanism, defect hierarchies, and mechanical properties of SWNTs.

Strength of carbon nanotubes depends on their chemical structures

“…1a) 1 , which can be viewed as cylindrically rolled graphene sheets 2,3 , have been predicted as game-changing structural materials due to their outstanding theoretical strength per weight (strength-to-weight ratio; Fig. 1a) 4–13 . Ultimate intrinsic tensile strengths of more than 100 GPa 4–13 have been predicted.…”

Comparative study of single‐layer graphene and single‐walled carbon nanotube‐filled epoxy nanocomposites based on mechanical and thermal properties

“…In this epoxy nanocomposites system, the incorporation of SLG and SWCNT into the epoxy matrix leads to an enhancement in the fracture toughness which is mainly due to the extraordinary strength and modulus of SLG and SWCNT. As reported previously in many studies, SLG and SWCNT possess a modulus of about 1 and 0.98 Tpa, respectively, and a strength of about 130 and 45 GPa, respectively, which are extremely higher than the modulus and strength of neat epoxy . Thus, the remarkable properties of SLG and SWCNT help the epoxy nanocomposite to withstand higher load thereby preventing them from being easily fractured.…”

“…SEM images of the neat epoxy at magnification of (a) 100×, (b) 500×, Epoxy/SLG at magnification of (c) 10,000×, (d) 30,000× and Epoxy/MIX at magnification of (e) 10,000× and (f ) 30,000×. and strength of neat epoxy [8,9]. Thus, the remarkable properties of SLG and SWCNT help the epoxy nanocomposite to withstand higher load thereby preventing them from being easily fractured.…”

“…However, both materials have exceptional properties which afford them as excellent candidates used as fillers in polymer composites [7]. Previously, it has been reported that graphene and carbon nanotubes possess extraordinary mechanical properties with ultimate strengths of 130 Gpa [8] and [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] Gpa [9], respectively, and Young's modulus of 1 Tpa [8] and 0.98 Tpa [9], respectively. Furthermore, graphene and carbon nanotubes have excellent thermal conductivity up to 5,300 W/mK [10] and 3,500 W/mK [11].…”

Understanding the Mechanical and Conductive Properties of Carbon Nanotube Fibers for Smart Electronics

“…Among the various computational methods, classical and coarse‐grained MD simulations are widely used to predict the fracture mechanics of defect‐embedded CNTs, intertube sliding or bonding, CNT–polymer contacts, deformation of CNT network, strength of CNT fibers and CNT/polymer composite fibers . These studies have cast intensive light on the structure–performance relationship of CNT fibers.…”