ORCID Identifier(s)

0000-0001-7081-3806

Graduation Semester and Year

2017

Language

English

Document Type

Thesis

Degree Name

Master of Science in Mechanical Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Ashfaq Adnan

Abstract

This research work consists of two phases. In phase one it is intended to manufacture an antibacterial 3D printable filament by extruding a solid state mixture of (MgO) nanoparticles (NPs) and Acrylonitrile Butadiene Styrene (ABS) pellets. A single screw extruder was used to extrude ABS pellets containing 0, 0.5, 1, 2 and 4 wt. % MgO NP. This phase deals with manufacturing and testing the filament for mechanical properties, antibacterial properties and 3D printability. On one hand tensile strength, ductility and 3D-printabiliy were observed to decrease with increasing concentrations of MgO NP in ABS matrix, on the other hand the extent of inhibition of microorganisms was found to increase with increasing concentration of NP. Moreover, diametric inconsistency of the extruded filaments was observed to increase with increasing NP concentrations. The 4 % filament was unprintable for the Fused Deposition Modelling (FDM) printer while the 2 % filament required several attempts in order to be 3D printed. A concentration of 0.5 wt. % of MgO inhibited the growth of Bacillus subtilis, whereas the filaments having 1 and 2 wt. % of MgO inhibited the growth of Klebsiella pneumoniae and Pseudomonas aeruginosa. The filament having no MgO NP did not exhibit antibacterial activity. Phase two of this research deals with determination of factors that decide the mechanical properties and 3D printability of ABS-MgO nanocomposite filament. Moisture in the hygroscopic MgO NPs (ILO-ICSC, 2010) was believed to be the reason for generation of voids therefore bringing about deterioration of mechanical properties and 3D printability of the nanocomposite filaments. The filament containing maximum w/w concentration (2%) of non-heated MgO NPs in unground ABS pellets was found to contain voids of largest average size and lowest average tensile strength; however, when a similar concentration mixture of 2% MgO in ABS (w/w) was made from heat dried MgO NPs and ground ABS pellets and then extruded, the average size of void inside the filament decreased by more than 90 % and the average ultimate tensile strength (UTS) of the filament increased by more than 84 %. Furthermore it was possible to 3D print the 2% filament containing ground ABS pellets and heat dried MgO NPs in a single iteration. These results indicate that pre-conditioning of the pellets and NPs is a deciding factor in preventing the deterioration of properties of an extruded nanocomposite material. With improved mechanical properties and 3D printability the two-step manufacturing method can be used to build smart objects that apart from bearing load would have antibacterial bacterial properties intrinsic to them.

Keywords

Antibacterial, 3D printable, 3D printer filament, 3D printing, Additive manufacturing, Functional filament, Nanocomposites, Single screw extrusion, Multifunctional, Preconditioning, World Health Organization, Antibacterial toys, Antibacterial plastic, Solid state mixing

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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