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, December 11, 2018

11:00 AM
in MaRC 431

will be held the

DISSERTATION PROPOSAL DEFENSE

for

Ejaz Haque

"Nanocellulose-based Glass Fiber Sizing for Lightweight Composites"

Committee Members:

Prof. Kyriaki Kalaitzidou, Advisor, ME

Robert J. Moon, Ph.D., RBI

Prof. Karl Jacob, MSE

Prof. Paul Russo, MSE

Prof. Mark Losego, MSE

Abstract:

The focus of this research is to understand interfacial interactions in polymer nanocomposites, specifically between cellulose nanocrystals (CNC) and glass fibers. This will be experimentally accomplished through addition of CNC onto the fiber surface, followed by mechanical characterization of the fiber-matrix interface and adjustment of said interface through systematic variation of CNC surface functionality, concentration, and dispersant. Identifying the mechanisms of interfacial enhancement will involve further characterization of chemical bonding behavior, surface energy, and CNC particle size.

Development of our understanding of nanomaterial interfaces is crucial for the automotive industry, whose future will be shaped by lightweight materials and the economic and environmental benefits they yield. Manufacturers have already begun replacing traditional metallics such as steel and aluminum in small quantities with fiber-reinforced composites (FRCs), which combine the toughness of a polymer matrix with the strength and stiffness of fibrous materials. However, FRCs fail to achieve the balance of strength, weight, and cost necessary to fully disrupt the status quo. Further reinforcement of the matrix through the addition of high-performance nanomaterials has shown potential in early research, but scalability is often limited due to the difficulty of achieving monodispersity in polymeric systems.

A possible alternative approach involves the isolation of nanomaterials to the fiber surface, as the properties of FRCs are primarily dictated by the fiber-matrix interface. Incorporation of nanomaterials into sizing, the protective coating applied to the surface of fibers during manufacturing, circumvents the challenge of mixing nanomaterials into the matrix, thus theoretically enabling substantial increases in composite strength while avoiding major processing bottlenecks in composite fabrication. This work details an experimental approach to accomplishing this using CNC, an abundant, renewable nanomaterial with a high strength to density ratio suitable for composite reinforcement. The chemical and mechanical characterization described herein will serve to advance our understanding of the interface at the molecular level, establishing a potentially scalable pathway to nanomaterial reinforcement for the production of cheap, efficient, and lightweight FRCs.

Keywords: composites, cellulose nanocrystals, fiberglass, interfacial characterization, surface analysis