THE SCHOOL OF MATERIALS SCIENCE AND ENGINEERING

GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY

on Friday, April 23, 2021

12:00 PM

via

Blue Jeans Video Conferencing

https://bluejeans.com/434194682

will be held the

DISSERTATION  DEFENSE

for

Edward DiLoreto

"Lightweight Approaches to Polyester Composites: Nanocellulose and Syntactic Foams"

Committee Members:

Prof. Kyriaki Kalaitzidou, Advisor, ME

Prof. Robert Moon, MSE

Prof. Karl Jacob, MSE

Prof. Donggang Yao, MSE

Prof. Douglas Fox, American University, CHEM

Abstract:

The focus of this research was to understand the effect of filler characteristics and composite processing in polyester composites on properties with the goal of realizing lightweight, high strength composites. Composites were made at both lab scale via open mold casting, and pilot scale via compression molding of sheet molding compounds (SMC). The impetus for this study is a recent trend towards lightweighting in the automotive sector, primarily driven by new fuel efficiency standards. In this study three different directions are explored, the first one is to add a high-performance nanomaterial, cellulose nanocrystals (CNC), into the composite to enhance the properties without increasing density. The second is to add a low-density material, hollow glass spheres (HGS), to reduce the density without compromising the properties. The synergistic effect of adding both in the GF/PR is also investigated. The third is to laminate SMC in a functionally graded arrangement to reduce density without compromising surface properties. Although nanodispersion was not achieved, the surface modified CNCs displayed an enhanced storage modulus and improved elastic modulus, all without significantly increasing the composite density. Surface coating of HGS with CNC was successfully completed. CNC coated HGS-PR composites displayed enhanced storage modulus and reduced maximum water uptake relative to untreated HGS-PR composites. Functionally graded SMC was manufactured and showed good lamination and similar bulk properties to a monolithic formulation of similar density. This project has advanced our fundamental understanding of how modification of composite filler surfaces and composite structures can customize material density and mechanical properties.