Mechanical behavior of carbon nanotube and graphene junction as a building block for 3D carbon nanostructures

Mina Moradi,Jamshid Aghazadeh Mohandesi

doi:10.1063/1.4936560

Abstract

The incorporation of defects in junction area of 1D and 2D carbon nanostructures has a major impact on properties of their 3D structures. In the present study, molecular dynamics simulation is utilized to examine the mechanical behavior of graphene sheet (GS) in carbon nanotube (CNT)-GS junctions. The tensile load was applied along the GS in connection with CNTs of different chiralities. The adaptive intermolecular reactive empirical bond order potential was chosen to model C-C interactions. It provided a reliable model for CNT, GS and their junctions. The results revealed that the connection of CNT to the GS with a hole could improve the mechanical properties of defective GS, which appeared to be independent of CNT type. It was found that the high strength C-C bonds postpone the crack propagation and motivates new crack nucleation. When a hole or CNT placed on the GS, it caused stress concentration, exactly along a line on its side. The lower mechanical properties were consequently associated with crack nucleation and propagation on both sides in a way that cracks encountered each other during the failure; while, the cracks in pristine GS propagate parallel to each other and could not encounter each other.

Highlights

During the last decade, carbon nanotube (CNT) and graphene sheet (GS) have attracted considerable attention of scientists owing to their extraordinary mechanical strength,[1,2,3,4,5] thermal conductivity[6,7,8,9] and anisotropic electronic properties.[10,11] These interesting properties are confined to the individual CNT and GS but their junctions exhibit novel properties that have not been observed in pristine building blocks
Molecular dynamics simulation is utilized to examine the mechanical behavior of graphene sheet (GS) in carbon nanotube (CNT)-GS junctions
The results revealed that the connection of CNT to the GS with a hole could improve the mechanical properties of defective GS, which appeared to be independent of CNT type

Summary

Introduction

CNT and GS have attracted considerable attention of scientists owing to their extraordinary mechanical strength,[1,2,3,4,5] thermal conductivity[6,7,8,9] and anisotropic electronic properties.[10,11] These interesting properties are confined to the individual CNT and GS but their junctions exhibit novel properties that have not been observed in pristine building blocks. Electrical and thermal rectification in CNT junctions has been well demonstrated theoretically and experimentally.[12,13,14,15,16,17] Mechanical behavior of five possible X-junctions of ultrathin CNT (4 Å in diameter)[18] under uniaxial[19] and biaxial[20] loading have been investigated These junctions mimic three stages behavior of individual CNTs i.e. elastic change in the bond angles, elastic altering the bond length and rapid bond breaking processes.[21] the junction deformation depends on defect structures at the connection area i.e. without “elastic bond length altering stage” when necking occurs in some types of junctions.[20]

Objectives

Methods

Results

Conclusion