Date of Award

12-2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

Committee Member

Dr. Huijuan Zhao, Committee Chair

Committee Member

Dr. Srikanth Pilla, Committee Co-Chair

Committee Member

Dr. Gang Li

Abstract

The paramount need for the development of multifunctional, smart and adaptive material systems for application in industries like automobile, aeronautical and aerospace is undeniable. Polymer composites are fast becoming the primary material options to this demand in light of their superior mechanical properties, low density, high corrosion resistance and easy manufacturability. The design flexibility offered in terms of achieving higher specific properties and light weighting is the key reason behind their success. Among all the properties that composites possess, it is the stiffness, strength and toughness that most applications mandate. These properties however, provide complimentary and contrasting characteristics for composites thereby limiting them for wide variety of applications. Hence it is critical to design composites with these triumvirate properties, which are capable of producing superior performance over their conventional counterparts.

This research aims at providing solutions to this problem by altering the constituent material architectures. ‘Roding’ architecture, innovated via this study, is an integration between ‘Rod’ and ‘Dampening’ elements. This is an ingenious design capable of realizing the above mentioned triumvirate properties, comprising of ‘Rod’ elements that are capable of improving the strength and stiffness and ‘Dampening’ elements that can enhance the toughness. This overarching goal of realizing these triumvirate properties in a composite material system can be achieved through various methods like iterating the combinations and modifications of the nanofiller’s shape, size, topology, chemical composition and even the surface charge. In this thesis however, this concept was proven via realizing the ‘Roding’ architecture at a nanoscale by covalently coupling ‘Rod’ like single walled carbon nanotubes and ‘Damper’ like hyperbranched polymers. This concept can potentially be translated into micro and macro scales to suit the mass production needs of the transportation industry. The catch here is not to restrict ourselves to a particular morphology but to explore the possibilities of customizing the composite material’s morphology, as per application needs.

Nanofillers with ‘Roding’ architecture were synthesized by optimizing the interplay between the individual nanoparticle’s shape, dimension, composition and interface. Integrating the triumvirate properties of strength, stiffness and toughness into the matrix by controlling the architecture of these nanofillers is the essence of this attempt. Once nanofillers with ‘Roding’ structure have been successfully synthesized, they were embedded into a thermoset matrix called ‘Diglycidyl ether of bisphenol-A’ (DGEBA). Techniques like FTIR, Raman, XPS, XRD, TGA, Gel Fraction, ATR and FE-SEM, have been used to characterize the physical, chemical and structural aspects of the hybrid ‘Roding Nanofillers’. This composite material then was also tested for its performance using standard tensile tests in order to analyze the properties of the material and the optimum loading ratios of the nanofillers. As expected the material exhibited increased strength and stiffness as well as mechanical toughness. A comprehensive study of potential applications of ‘Roding’ nanofillers into the more processable thermoplastic resins is presented. ‘Roding’ Nanofillers are but an example of the materials that can be custom made by engineering their morphology, to suit customer needs. In a gist, advanced nanocomposites with higher order smart architectures that have the potential to exhibit triumvirate properties of strength, stiffness and toughness have been synthesized and tested for performance.

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