Doctoral Dissertations
Date of Award
8-2022
Degree Type
Dissertation
Degree Name
Doctor of Philosophy
Major
Chemistry
Major Professor
S. Michael Kilbey
Committee Members
Gila E. Stein, Bin Zhao, Konstantinos D. Vogiatzis
Abstract
Fused filament fabrication (FFF), a subset of additive manufacturing (AM), deposits polymeric feedstock material in a layer-by-layer fashion to generate 3D printed parts enabling rapid prototyping. The lack of feedstock material limits the properties of the printed parts and therefore the desire to create new material that expands the boundaries of these properties is a necessity. Since existing materials used to produce printed parts have mechanically inferior properties when compared to other manufacturing techniques, reinforcing the polymeric materials with additives presents a new route to systematically design feedstock materials. My dissertation work focuses on how the design and incorporation of the additives in the nanocomposites drastically improves the printed parts properties. More specifically, I evaluated the mechanical properties and dispersion of polymer grafted nanoparticles (PGNPs) through two different additive incorporation methods and determined that a solution-based method of incorporation enables better dispersion of the additives with better structural reinforcement in the printed parts. Additionally, these solution-based incorporation method decreased the part-to-part variation for the FFF process. Subsequently, PGNPs containing a hydrogen bonding motif drastically improved the mechanical properties of poly (methyl-methacrylate) (PMMA). Microscopy imaging and analysis revealed more homogenously produced printed parts via the solution casting method and greater levels of the additives were present at road and surface interfaces than that of the mechanically mixing incorporation method. Reduced graphene oxide (rGO) enhanced the electrical conductivity of PMMA printed parts to a semiconducting range while providing slight structural reinforcement. High loading levels of the rGO additive proved to be unprintable without using the solution-based method of incorporation. The results from these studies demonstrate how additive design can be used to tailor specific properties through changes in the nanofiller in the nanocomposites. These studies exemplify advantageous approaches to solve common FFF issues and can be steppingstones in overcoming more challenges associated with AM.
Recommended Citation
Ledford, William K., "Using Nanomaterials as Additives in Fused Filament Fabrication to Improve Mechanical Properties and Conductivity. " PhD diss., University of Tennessee, 2022.
https://trace.tennessee.edu/utk_graddiss/11572