Date

2016-8

Author

Fatima, Bushra

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In this study, multi-walled carbon nanotubes (MWNTs) and multi walled carbon nanotube reinforced epoxy composites (CNTRPs) are investigated by means of computational modelling. To begin with, individual tubes of MWNTs are modelled with varying chiralities through equivalent continuum modelling in order to examine their essential mechanical properties including Young’s modulus, shear modulus, and Poisson’s ratio. The finite element models developed incorporate beam elements that represent Carbon-Carbon bonds within each nanotube and spring elements that represent van der Waals interaction between concentric tubes. Unlike the models reported in literature, this study considers the variation of intershell spacing with varying inner diameters. Similarly, the literature has so far neither reported any results for the chiral configuration of MWNTs nor have reported any comparison between polychiral and monochiral configurations. This study determines the properties of MWNTs by considering both the polychiral and monochiral configurations. Novel relationships of tensile resistance and torsional stiffness are also obtained in terms of outer tube diameter of an MWNT. In the second part of the thesis, CNTRPs are modelled that embed 5 percent by volume of MWNTs, already modelled in the first part, as reinforcement elements in the epoxy resin. Continuum modelling and discrete modelling approaches are employed to model CNTRPs. In the former model, the interphase region is assumed to have perfect bonding with the polymer matrix and the MWNT, whereas in the latter the interphase is modelled using weak Van der Waals interactions that are characterized by Lennard-Jones “6-12” potential. The simulated Young’s moduli show good agreement with the published computational results and analytical continuum rule of mixtures. In addition, influence of chirality and size of MWNTs on the Young’s modulus and Poisson’s ratio of CNTRPs are also studied. In general, CNTRPs reinforced with polychiral MWNTs are stiffer than the ones reinforced with monochiral MWNTs which are more resistant to lateral deformation.

Subject Keywords

Multi-walled carbon nanotube, Carbon nanotube reinforced epoxy composite, Van der Waals, Finite element method, Polychiral, Monochiral, Continuum modelling, Discrete modelling

URI

https://hdl.handle.net/11511/69711

Collections

Northern Cyprus Campus, Thesis