Study On The Mechanical Properties Of Carbon Nanotubes Containing "Junction" Carbon Nanotubes And The Embedding Behavior Of Graphite Belt In Carbon

Contents of this paper are divided into two parts:(1) Torsional mechanical properties of the carbon nanotubes with junctions;(2) Behavioral characteristics of the interaction between graphene nanoribbons and carbon nanotubes. Torsional mechanical behavior of carbon nanotubes and electrical force characteristics of carbon nanotubes’heterojunction have important implications for the design and application of nano-electronic mechanical systems. Many scholars have made some deep studies of the mechanical properties of carbon nanotubes and the electrical properties of junctions. However, the study of torsional mechanical properties of the carbon nanotubes with junctions is not enough at present. Clearly, the study of mechanical properties of carbon nanotubes with junctions may be an important part of effective use of its electrical and mechanical properties coupling effect. Besides, interactions with graphene nanoribbons and carbon nanotubes may have important implications for understanding the formation mechanism of multi-walled carbon nanotubes.During the study of the mechanical properties of carbon nanotubes with junctions when rotating them, we built two models:(1) The single-wall carbon nanotube (SWCNT) model with junction which consists of a circunference band of alternating5-and7-membered rings is linked by the armchair (n, n) and zigzag (2n,0) carbon nanotubes;(2) The single-wall carbon nanotube models with trapeziform junctions are linked by the (m, m) and (n, n) of armchair carbon nanotubes and by the (m,0) and (n,0) of the zigzag nanotubes. We axially constrained the two ends of our models during torsion, and calculated the axialforce and the torque of carbon nanotubes with junctions which had various diameters’in torsional process by molecular dynamics (MD). There torsional shapes and stress distribution were analyzed to get some meaningful results:(1) Before the torsional buckling, the carbon nanotubes which have right size of diameters with junctions which consist of a circunference band of alternating5-and7-membered rings can eliminate the inherent Poynting effect of ordinary carbon nanotubes during torsion, and this could be applied in the designing of the torsional pendulum.(2) There are multiple buckling points arised in the changes of torsional torque of carbon nanotubes with junctions which consist of a circunference band of alternating5-and7-membered rings during torsion, in general, the arising of each buckling point brings an emergency of a knot, but to the torsional shap, when there is a knot arises, it does not correspond to the appearancec of new buckling point.(3) Both of the armchair style and the zigzag style carbon nanotubes with trapeziform junctions can lead to the phenomenon of bending and then straightening in torsional process, this is caused by the difference of torsional stiffness between the two different segments of carbon nanotube which are distributed at the right side and the left side of the trapeziform junctions, and it is also related to the special structure of the trapeziform junction.(4) To the carbon nanotubes with junctions, the "junction" parts always have the smallest torsional stiffness, and the stress is arised first at the parts of junctions, and then spread to the two different segments which one is at the right side and the other is at the left side of the "junction" part, when rotating, the torsional shape first appears at the segment with smaller torsional stiffness and then influences to the segment with stronger torsional stiffness.In the study of the interaction between graphene nanoribbons and carbon nanotubes, we employed molecular dynamics (MD) simulations to calculate and analyzed the interaction between the graphene nanoribbons with different widths and single-wall carbon nanotubes with different diameters. We found that the process of graphene nanoribbons encapsulating single-wall carbon nanotube is spontaneous. Those dangling bonds of graphene nanoribbon and ends of single-wall carbon nanotube are removed in random bonding ways for edge atoms of graphene nanoribbon and single-wall carbon nanotube during the process of graphene nanoribbon encapsulating so that graphene nanoribbon can display different configurations in single-wall carbon nanotube.