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In this paper, an investigation into the thermal conductivity of cross-linked functionalized carbon nanotubes under physical adsorption of polyethylene (PE) chains (cfCNTs/PE) is performed using molecular dynamics (MD) simulations. To have a comprehensive study, the covalently attached functional groups with two types of distribution patterns, namely mapped and wrapped configurations, are used. The cfCNT/PE shows a smaller thermal conductivity than that of pure one. Also, the results demonstrate that the thermal conductivity of cfCNTs reduces by the physisorption of PE chains. By rising the weight percentage of physisorbed PE, the thermal conductivity of cfCNT/PE reduces more. Based on the results, for the constant weight percentage of non-covalent PE chains, the thermal conductivity increases as the number of cross-linked PE chains augments. [ABSTRACT FROM AUTHOR]

Herein, the interfacial properties of new three-dimensional (3D) configurations of metallic carbon, namely T6 and T14, incorporated to different polymer matrices (T6 and T14@polymers) are studied using molecular dynamics (MD) simulations. The effects of two types of shape models for T6 and T14, i.e. beam- and plate-like models, various square cross-sectional areas for the reinforcements, pull-out velocity and polymer structure on the interaction energy and pull-out force of final system are investigated. The results reveal that the interfacial resistance of the system is improved by imposing a high pull-out velocity to the nanofillers. For each pull-out velocity, the effect of beam-like T6 and T14@polycarbonate (beam-like T6 and T14@PC) on increasing average pull-out force is more remarkable than that of similar models surrounded by polypropylene (PP). The beam- and plate-like structures@polymers possess the lowest and highest interfacial resistance, respectively. As the aspect ratio (length-to-width ratio) of nanofillers changes from the lowest value to the highest one, the average pull-out force decreases. The average pull-out force of plate-like T6@polymers is higher than their plate-like T14 counterparts. Besides, higher absolute values of interaction energy in plate-like T6 and T14@polymers in comparison with others imply that the load-carrying capacity from the surrounding matrix to the plate-like nanofillers is significantly increased. Image 1 • Studying the interfacial properties of T6 and T14 structures incorporated to different polymer matrices (T6 and T14@polymers) using MD simulations • Using two types of configurations for T6 and T14 (beam- and plate-like models) • Investigating effects of square cross-sectional areas for the reinforcements, pull-out velocity and polymer structure on the pull-out force and interaction energy [ABSTRACT FROM AUTHOR]

In this paper, the free vibration of hybrid carbon boron-nitride heteronanotubes (CBNNTs) is analyzed through molecular dynamics (MD) simulations. In the vibration analysis, various CBNNTs (C x ∣ (BN) y and C-BN models) according to two geometrical arrangements of constituent segments are considered. By introducing vacancy defects in nanotubes, the influence of defects on the vibrational response is studied in terms of the weight percentage and distribution pattern. The highest vibration frequency is reported and CBNNTs' results are compared with those of carbon nanotubes (CNTs) and boron-nitride nanotubes (BNNTs). It is observed that CBNNTs possess natural frequencies which lie between the values for CNTs and BNNTs. The natural frequency is found to be reduced by increasing the defect percentage. At each defect percentage, the defective C-(BN) model I and C 1.5 ∣ (BN) 1.5 experience almost the same natural frequency in both distribution patterns. Vibration frequencies of defective C-(BN) model II and C 4.5 ∣ (BN) 4.5 are nearly close together at a defined percentage of defects. Despite the minor differences between natural frequencies in either distribution pattern, regularly defected CNTs tend to have a bit higher frequency than randomly defected CNTs, however, the results are opposite in the regularly and randomly defected BNNTs. Moreover, the C-(BN) model II vibrates at a higher natural frequency than that of the C-(BN) model I. It is found that the vibrational behavior of the C-(BN) model I is mostly affected by the BN segment than the C segment. Further, the natural frequency's drop in the defected C 1.5 ∣ (BN) 4.5 is found to be more significant than other CBNNTs by rising the defect percentage. C-(BN) model I and defective C-(BN) model I experience higher deformations in comparison with the C x ∣ (BN) y configurations when vibrating at their natural frequency. [Display omitted] • Vibrations of hybrid CBNNTs are analyzed using MD simulations. • Vacancy defects are considered in the analysis. • Natural frequencies of CBNNTs are between those of CNTs and BNNTs. • Natural frequency is decreased by introducing the defect sites. [ABSTRACT FROM AUTHOR]

The buckling behavior of cross-linked functionalized carbon nanotubes (CNTs) with polyethylene (PE) chains under physical adsorption of polymers (cfCNTs/polymer) is studied by classical molecular dynamics (MD) simulations, and the results are compared with those for the pure CNTs under the physical adsorption of polymers. Considering non-covalent functionalization, the effect of type of functional group, i.e. aramid and PE chains, on the interactions between polymers and cfCNTs is investigated. Based on the results, the gyration radius of cfCNTs/polymer increases by raising the weight percentage of non-covalent polymer chains. Also, the simulation results for most cases demonstrate that the gyration radius of cfCNTs/polymer is larger than that of pure CNTs/polymer for the similar weight percentage of non-covalent polymer chains. Moreover, the critical buckling force and the critical buckling strain of the cfCNTs/polymer are lower than those of pure CNT/polymer for the similar weight percentage of non-covalent polymer chains, although some exceptions can be observed. Besides, by raising the weight percentage of non-covalent polymer chains, the critical buckling force cfCNTs/polymer increases for a specific weight percentage of cross-linked PE chains. [ABSTRACT FROM AUTHOR]

Fabrication of novel metallic and stable three-dimensional (3D) forms of carbon, i.e. T6 and T14, has recently attracted a lot of interest due to their various potential applications. In the present work, the vibrational behaviors of T6 and T14 with interlocking hexagons are studied via molecular dynamics (MD) simulations. The natural frequencies and mode shapes of T6 and T14 are obtained for beam- and plate-like models. Moreover, the effects of different geometrical parameters such as length, width and cross-sectional area on the vibrational behaviors of these nanostructures are investigated. Also, the natural frequency of models is compared to that of single-walled carbon nanotubes (SWCNTs) with relatively similar dimensions. The results indicate that the natural frequency is strongly sensitive to the geometry, especially in the models with shorter lengths. Furthermore, it is observed that the natural frequency of 3D metallic carbon nanostructures is smaller than that of SWCNTs. [ABSTRACT FROM AUTHOR]

Abstract Young's modulus and the fracture of gold nanowires (GNWs) encapsulated inside single-walled carbon nanotubes (SWCNTs) are studied using molecular dynamics (MD) simulations. To investigate the mechanical behavior, two important parameters, i.e. ultimate tensile force and strain, are calculated. The obtained results from aforementioned nanostructures are compared with those of pure GNWs and SWCNTs. The results illustrate that SWCNTs filled with GNWs (GNWs@SWCNTs) and pure GNWs possess lower Young's moduli than those of pure SWCNTs in a similar length. As the length increases, Young's modulus of pure GNWs and GNWs@SWCNTs is reduced. In a particular length, the highest and lowest ultimate forces belong to the multishell GNWs@SWCNTs and pure multishell GNWs, respectively. Moreover, it is found that pure SWCNTs have the highest ultimate strains. Also, by rising the length, the ultimate tensile strain increases. To study the effect of selected boundaries on the tensile characteristics, the tensile loads are applied to the boundaries of surrounding SWCNTs instead of whole configuration (B model). The obtained results demonstrated that in the similar length, Young's modulus and ultimate force for B model are higher than those of A model, i.e. the model that the whole system is under the tensile loads. By contrast, in the particular length, B model shows lower ultimate strain compared to that of A model. Graphical abstract Unlabelled Image Highlights • Studying Young's modulus and fracture of GNWs@ SWCNTs by MD simulations • Calculating ultimate tensile force and strain • Considering effects of length and various cross-sectional area of GNWs • Comparing the results with those of pure GNWs and SWCNTs [ABSTRACT FROM AUTHOR]