Si mulation insights i nto the th ermal conductivity of carbon nanotube s bundles and carbon na nocomposites: A re verse non- equilibri um molec ular dyn amics stu dy

Understanding and modeling thermal tra nsport prop erties in na nostructured materials is an important concern for the design of high-performance nanoscale devices for specific applications. Ind ividual car bon nanotubes (CNTs ) typically self-assemb le into bundles containing tens to hundreds of hexag onally clos e-packed n anotubes [۱]. The thermal conductivity of the bundles in the directi on perpendi cular to the tube axis is considerable less than t he parallel value. This r eduction is due to those phonons, as predominant energy ca rriers in car bon nanostr uctures, which scattered at the interfaces. Here, in this study , we have chosen a (۱۰, ۱۰) nanotubes bundle. Using rever se non-equilibrium molecular dyna mics simul ations (RNEMD) [۲], the thermal c onductivity of the CNT bundle is investigated. The measured thermal conductivities showe d a value of about ۰.۵ W m-۱ K-۱ in the direction perpendicu lar to the tube axis at ۳۰۰ K, while the parallel values are about two to three orders of magn itude larger [۳]. Thus, although individual CNTs possess high axial conduc tivity as a best conductor, the bu ndles of CNTs act as an insulator i n the perpendicular direction of tube axis i.e., an isotropy in the thermal conductivit y. In addition to the neat CNTs bund les, we have also studied the CNT-polymer an d graphene- polymer nan ocomposites to understand the ori gin of the relatively low thermal conductivity in the nanocomposites. The main reason is the high interfa cial thermal resistance between the nanotubes and the polymer which hinders heat to be transf erred from the slow-conducting polymer into the fast-con ducting nan otubes and back into th e polymer.

کلیدواژه ها:

CARBON nanotubes ، molecular dynamics ، nanostructures ، polymer nanocomposite ، thermal conductivity