Molecular Modeling for Calculation of Mechanical Properties of Polyaniline-Carbon-Nanotubes

Author(s):  
Mariana Ionita

Atomistic models of polyaniline (PANI)-single walled carbon nanotubes (CNTs) were built in order to assess the effect of quantity and quality of CNTs and temperature on the calculated mechanical properties of PANI. Three different types of CNTs were considered: single walled carbon nanotubes m-polyaminobenzene sulfonic acid functionalized (CNTs-PABS), single walled carbon nanotubes octadecylamine functionalized (CNTs-ODA) and single walled carbon nanotubes carboxylic acid functionalized (CNTs-CX). Atomistic models were built for PANI-functionalized CNTs with a range of CNTs content, contained within periodic boundary conditions and were subject of multistage equilibration procedure. In order to test the mechanical behaviour of the models virtual uniaxial traction tests along the three perpendicular edges of the models were performed. The Young’s moduli generally increased with increasing of CNTs content and values range from 0.48 GPa in the case of pure PANI to 1.35–1.83 GPa in the case of PANI-CNTs-PABS composite system.

Author(s):  
Paola Jaramillo ◽  
Haym Benaroya

Carbon nanotubes are composed of C-C covalent bonds, which are the strongest bonds found in nature. Hence, carbon nanotubes are identified as the “ultimate fiber” due to their great strength in the direction of the nanotube axis and their ability to enhance the elastic properties of materials. The first indications of synthesizing carbon nanotubes date back to 1952. Russian scientists Radushkevich and Lukyanovich [1] were able to produce nanosized hollow carbon filaments. Nevertheless, it was until 1991 that multi-walled carbon nanotubes (MWCNTs) were discovered by Sumio lijima [2, 3] at NEC Corporation Lab, which was followed by his study and synthesis of single-walled carbon nanotubes (SWCNTs) in 1993. Since their discovery, there has been a constant pursuit to understand the properties and identify the optimal applications of these structures. The paper focuses on the importance of carbon nanotubes and their ability to enhance the mechanical properties of other materials due to their unique elastic properties. Additionally, carbon nanotubes can improve the capabilities and properties of other materials, like polymer composite. Currently, there is an ongoing process to accurately understand the fundamental characteristics of these structures, in particular, to develop the governing laws necessary to control, predict, and manipulate these properties. This will eventually have an impact on the bulk properties of materials where carbon nanotubes may be incorporated. The current research focuses on the ability to create simplified models that can accurately predict the response of carbon nanotube structures undergoing different types of loading conditions. In this way, the mechanical characteristics regarding single-walled carbon nanotubes (SWCNTs) through finite element modeling are computed. A simplified finite element model is created in ANSYS for different types of SWCNTs with varying input parameters. An input array for the elastic modulus and load is generated to control the physical effects of these parameters in the nanotube structure. The geometries of the nanotubes are altered through various thicknesses employed for the construction of the C–C bonds. The current work contributes to the generation of different model responses to monitor the stress distribution employing a wide range of parameter values. The ability to introduce variability in the parameters and boundary conditions without altering the capabilities and computational time in the model represents the main contribution of this work.


Author(s):  
Saeed Rouhi ◽  
Seyed H Alavi

In this paper, the elastic properties of functionally graded materials reinforced by single-walled carbon nanotubes are studied. Three different matrices, including steel-silicon, iron-alumina and alumina-zirconia are considered. Besides, the effects of nanotube length, radius and volume fraction on the Young’s modulus of functionally graded matrices reinforced by single-walled carbon nanotubes are investigated. It is observed that short nanotubes not only cannot increase the longitudinal elastic modulus of the matrices, but sometimes decrease their elastic modulus. Of the three selected matrices, steel-silicon matrix would have the most enhancement. Investigation of the effect of nanotube volume fraction on the mechanical properties of nanocomposites shows that increasing the volume fraction of long single-walled carbon nanotube results in increasing the elastic modulus of the nanocomposites.


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