Transversal thermal transport in single-walled carbon nanotube bundles: Influence of axial stretching and intertube bonding

Abstract

Using reverse nonequilibrium molecular dynamics simulations the influence of intermolecular bridges on the thermal conductivity (λ) in carbon nanotube (CNT) bundles has been investigated. The chosen cross linkers (CH2, O, CO) strengthen the transversal energy transport relative to the one in CNT bundles without bridges. The results showed that λ does not increase linearly with the linker density. The efficiency of the heat transport is determined by the number of linkers in the direction of the heat flux, the type of the linker, and their spatial ordering. The influence of a forced axial stress on the transversal λ has been also studied. The observed λ reduction with increasing axial stretching in a neat CNT bundle can be (over)compensated by cross linkers. The present computational data emphasize the contribution of phonons to the transversal heat transport in CNT bundles with intertube bonds.

Interfacial thermal transport and structural preferences in carbon nanotube–polyamide-6,6 nanocomposites: how important are chemical functionalization effects?

“…56 has been employed for the polymer matrix. 14,26,27,33,52 The Lorentz-Berthelot mixing rule has been used to describe the interaction between the polymer matrix and the nanotube. In contrast to these uncharged fragments, the amide hydrogens, carbons and nitrogens as well as the oxygen atoms carry nonzero charges in the adopted f1-UA force field.…”

“…To model the grafted PE chains we have adopted the united atoms force field originally introduced by Paul et al 57 Also this force field couples the hydrogen and carbon atoms of the CH 2 and CH 3 moieties to a single united atom fragment. 27 Thus these tube atoms do not participate in a perfect cylindrical CNT shape. The PE chains grafted to CNT contain either 10, 20 or 40 united atom methylene groups, corresponding to L = 5, 10, 20 monomers.…”

“…In contrast to this enhancement the thermal conductivity in the perpendicular direction is reduced. 26,27 When considering the information mentioned above, it should not be a surprise that neither experiments nor computer studies of the MD type on CNT-polymer composites reported l values significantly larger than in the bare polymer. [10][11][12][13] Even in the absence of chemical bonds between the different polymer components the phonon density of states (DOS) profiles have been employed to explain or to predict the heat transfer in these systems.…”

Review of Recent Developments on Using an Off-Lattice Monte Carlo Approach to Predict the Effective Thermal Conductivity of Composite Systems with Complex Structures

“…This is because at low $R_{\text{SWNT-SWNT}}$, heat prefers to transfer through SWNT-SWNT contacts, thus the SWNT bundles would be more effective heat transfer channels than the mono-dispersed SWNTs. It can be inferred that the detrimental effect of the SWNT bundles could be reduced by decreasing the $R_{\text{SWNT-SWNT}}$ to be less than $R_c$, which may be achieved by covalent functionalization to enhance the phonon coupling and weaken the phonon scattering at a SWNT-SWNT interface [58,59]. …”

Understanding thermal conductance across multi-wall carbon nanotube contacts: Role of nanotube curvature

“…Currently, there exists a disconnection between experimental and simulation efforts from the perspective of addressing questions projected above. While most thermal conductance experiments have been performed on MWCNTs (diameter > 20 nm up to 100s of nm) [15][16][17][18][19] primarily due to experimental challenges, almost all numerical modeling has been performed on singlewall CNTs (SWCNTs) (diameter < 2 nm), because of the limitations associated with computational costs [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. In this study, we aim to bridge this gap by performing comprehensive molecular dynamics (MD) simulations with more realistic models for the first time, i.e., modeling contact thermal conductance between MWCNTs up to 8 nm diameter and up to 10 walls along with modeling their flat graphitic counterparts, i.e., multi-layer graphene nano-ribbons (MLGNRs).…”