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A hierarchical multiscale modeling approach towards the estimation of the elastic properties of CNT-polymer nanocomposites with damaged CNTs

Gustavo Domínguez Rodríguez (Centro de Investigación Científica de Yucatán, Unidad de Materiales), Gary Seidel (Virginia Polytechnic Institute and State University), Jorge Tapia González (Universidad Autónoma de Yucatán), Francis Avilés Cetina (Centro de Investigación Científica de Yucatán, Unidad de Materiales)

Advances in Nanocomposites for Thermal and Structural Applications

Tue 4:20 - 5:40

Barus-Holley 165

The introduction of defects in the carbon nanotube (CNT) structure formed during CNT synthesis, functionalization, or during fabrication of CNT/polymer composites can reduce the CNT mechanical properties. Here we explore the influence of various states of damage in CNTs on the effective mechanical properties of polymer nanocomposites (NCs) through a hierarchical multiscale modeling strategy. Analysis begins with the assessment of damage effects on CNTs using an atomistic finite element analysis (FEA) approach where covalent bonds between carbon atoms are modeled as beams whose elastic properties are based on the mechanical deformation energy of the bonds in a molecular mechanics approach. Atomistic FEA, requiring less computational resources than ab initio methods, allows one to analyze different nanostructures, i.e. CNTs with different chirality, lengths, and distribution of vacancies. Density functional theory was used to identify the valid range of application of the atomistic FEA approach through a direct comparison of the properties predicted for different undamaged CNT structures. Effective undamaged and damage CNTs are then used to construct polymer NC representative volume elements, the effective properties of which are obtained from a Mori-Tanaka approach using a combination of analytic and computational methods to obtain the requisite dilute strain concentration factors. For example, the Eshelby solution can be used for the undamaged CNTs, whereas the composite cylinder method can be used when the undamaged CNTs are coated with an interphase layer (representing load transfer), while for damaged CNTs, FEA approaches are used. Finally, the mulsticale modeling approach is applied towards predicting the effective properties of composites consisting of CNTs with different levels of damage, interphase properties and random orientation distribution, allowing for a reasonable comparison with experimentally obtained NC mechanical properties.