Date of Award

2019-01-01

Degree Name

Master of Science

Department

Mechanical Engineering

Advisor(s)

David . Espalin

Abstract

Additive manufacturing has seen continuous advancements, such as the inclusion of large-area additive manufacturing extrusion systems. These systems precede small-scale 3D printing by means of research and technological development for the manufacturing of plastic and fiber industries. Big Area Additive Manufacturing (BAAM), a material extrusion process, is capable of 3D printing large parts using thermoplastic composites by adding fiber reinforcements. The incorporation of fibrous materials, carbon fiber (CF) or glass fiber (GF), is a common practice in which percentage nominal ratios of fiber reinforcement by weight are implemented to the polymer matrix. In general, this enables warpage reduction during printing, increases stiffness and provides thermal stability to the three-dimensional printed part. This work focused on the thermophysical changes, by thermogravimetry (TGA) and differential scanning calorimetry (DSC), of thermoplastic matrix composites reinforced with either glass or carbon fiber. Specifically, the composite materials contained a matrix of acrylonitrile-butadiene-styrene (ABS) filled (by weight) with 20% CF, 20% GF, or 40% GF. In addition, another thermoplastic composite material contained poly (ethylene terephthalate)-glycol (PETG) filled (by weight) with 30% GF. The materials were tested in pelletized form (i.e., as received by the material manufacturer and before processing with the BAAM machine) within a controlled temperature profile and a low conductive inert atmosphere, as prescribed by ASTM standards. As such, through thermal stability experimental studies (i.e., TGA), the material's one percentage weight loss as a result of exposure to elevated temperatures (the decomposition temperature) was determined. Through software analysis with Trios v4.5.1 and thermogravimetric profile observations, the step transition events were identified via mass loss. In the same manner, residual measurements at 750 °C (mass change plateau) allowed making observation about the manufacturer-specified filler reinforcement. The inclusion of the derivative thermogravimetry peak temperature enable to report the maximum deflection point attained in the differential thermogravimetric (DTG)curve. In addition, the area under the DTG deflection allowed making observation as to the mass loss events. Thereafter, DSC studies at fixed heating and cooling scanning rates traced the glass transition events, and the endothermic and exothermic events.

Language

en

Provenance

Received from ProQuest

File Size

233 pages

File Format

application/pdf

Rights Holder

Fernando Adrian Rodriguez Lorenzana

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