Catalysis and manufacturing of two-scale hierarchical nano- and microfiber advanced aerospace fiber-reinforced plastic composites

The development of hierarchical nanoengineered "fuzzy fiber" aerospace fiber-reinforced plastic (FRP) composite laminates holds the potential for enabling future generations of lightweight, durable, and multifunctional vehicle structures. By reinforcing the weak matrix-rich regions between individual fibers and plies, the circumferential growth of aligned carbon nanotubes (A-CNTs) on carbon microfibers (CFs) enables new composites with improved strength, toughness, electrical and thermal properties. While these improvements have been empirically demonstrated on alumina fiber FRPs, CNT growth degrades the CFs and sacrifices in-plane FRP properties for the benefits of CNT reinforcement. This thesis presents novel and scalable methods for realizing advanced fuzzy carbon fiber reinforced plastic (fuzzy CFRP) composite laminates with retained CF and interlaminar strength properties. Earth-abundant sodium (Na) is revealed as a new facile catalyst for CNT growth that allows for direct deposition of the catalyst precursor on carbon fabrics without any fiber pretreatments. This new catalyst discovery also enables high-yield CNT growth on a variety of low-temperature substrates. Simultaneously, this finding has led to other novel findings in carbon nanostructure catalysis including a core-shell morphology and the use of other alkali metals (e.g., potassium) for CNT growth. Towards the development of advanced composites, vacuum-assisted resin infusion processes are studied and refined, resulting in high-quality woven and unidirectional fuzzy (via Na-catalysis of CNTs) CFRP laminates. Growth uniformity improvement studies yielded strategies for increasing the quantity of CNT reinforcement within matrix-rich regions. Moreover, a new commercial unidirectional fabric enables the first retention of CF properties concomitant with interlaminar shear strength retention in the fuzzy CFRP architecture. The contributions of this thesis extend beyond CF composites: techniques developed for improving fuzzy CF synthesis were applied towards demonstrating A-CNT growth on SiC woven fabric, desired for creating damage tolerant and multifunctional lightweight vehicle systems. These advances pave the way for improvements in catalysis of nanostructures, electronics interfaces, energy storage devices, and advanced composite materials.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Aeronautics and Astronautics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2018

Author dc:creator

• Li, Richard, Ph. D. Massachusetts Institute of Technology

Advisor dc:contributor.advisor

• Brian L. Wardle.

• Aeronautics and Astronautics.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/120419

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/120419