A two-level homogenization method for polymer nanocomposites with coated inclusions

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2021-2-04

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Güzel, Dilek

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Polymer nanocomposites are materials which have polymer matrices and nano-scalereinforcement elements. Other than the matrix and the reinforcement element, an-other phase in nanocomposite systems has been observed and some of the propertyenhancement or deficiency has been attributed to this phase. The third phase inthe composite system is known as the interphase. The local properties of polymernanocomposites are not easy to distinguish since the length scale is very small andcharacterization at the nano-scale is not a simple procedure. Macroscopic behaviorof nanocomposites can be deducted by homogenization of a representative volumeelement in many different ways. The aim of the thesis is to propose a new homoge-nization approach to model the polymer nanocomposites with coated inclusions. Un-derstanding the structure of nanocomposites, formation of the interphase and differentcharacterization techniques for the interphase are important for this aim. Interphaseproperties affect the overall macroscopic mechanical behavior. So it is important tomodel the interphase and obtain the effective composite properties accordingly. Dif-ferent homogenization techniques and applications related to this problem are studiedand a new approach is proposed. This method aims to model load transfer betweenthe matrix and the reinforcement element through the interphase in a correct way.Furthermore, a computational gain is aimed with the proposed model in comparisonto a full three-phase finite element simulation. Another goal is to extend the proposedmethod to viscoelasticity. For this purpose two-dimensional and three-dimensional fi-nite element codes are developed for a viscoelastic homogenization framework. Theformulations regarding the viscoelastic homogenization are derived and presented.

Subject Keywords

Homogenization, Coated inclusion, Interphase, Polymer nanocomposites

URI

https://hdl.handle.net/11511/89650

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

D. Güzel, “A two-level homogenization method for polymer nanocomposites with coated inclusions,” M.S. - Master of Science, Middle East Technical University, 2021.