THE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING

GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY

on Tuesday, June 14, 2016

2:00 PM
in MRDC 3515

will be held the

DISSERTATION PROPOSAL DEFENSE

for

Matthew Orr

"Constructing Tensegrity-Inspired Microstructures in a Polymer Nanocomposite with Cellulosic Nanomaterials"

Committee Members:

Prof. Meisha Shofner, Advisor, MSE

Prof. Karl Jacob, MSE

Prof. Christopher Luettgen, ChBE

Prof. Carson Meredith, ChBE

Prof. Donggang Yao, MSE

Abstract:

Polymer nanocomposites have seen growing interest in several fields over recent decades. Nano-sized reinforcement materials offer the promise of increasing thermal, mechanical, optical, and electrical performance of polymers. Cellulosic nanomaterials, including cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs), are currently popular materials in research due to their excellent mechanical properties and derivation from renewable sources, i.e. trees. Prescribing microstructures in polymers with nanomaterials offer the promise to tailor polymer properties to specific applications. One such prescribed microstructure is based on the idea of tensegrity in which a discontinuous phase (nanomaterial) is in a state of compression enveloped by a continuous phase (polymer) that is in tension. The purpose of the research is to construct and characterize tensegrity-inspired microstructures with cellulosic nanomaterials in a polymer nanocomposite construct. The proposed research will test the hypothesis that tensegrity-inspired microstructures can increase the mechanical and gas barrier performance of poly(ethylene-co-vinyl alcohol) (EVOH). Four tasks have been proposed to test this hypothesis. The first task will investigate processing strategies to incorporate and disperse cellulose nanocrystals in the copolymer matrix. The resulting isotropic polymer nanocomposites will be characterized to determine the degree of CNC dispersion in the copolymer matrix as well as thermal, mechanical, and rheological properties. The next task will investigate an additional processing strategy to construct and characterize prescribed microstructures in the polymer nanocomposite. The microstructures will be constructed with biaxial mechanical stretching and characterized for thermal, mechanical, and morphological properties. Once these processing strategies have been determined, the next task will investigate the cellulose nanocrystals’ effects on the microstructure of EVOH both before and after the tensegrity-inspired microstructures have been constructed. Finally, prescribed microstructures will be constructed and investigated in a polymer nanocomposite system with CNF as the reinforcement material to determine performance and structural differences and similarities to polymer nanocomposites reinforced with CNCs.