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" ''This new species of affliction'': "
Nieman, John Patrick
Lewis, Jayne E
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Latin Dissertation
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English
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| Record Number
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1051065
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TL50182
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Tsui, Michelle
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Mechanics of Rigid Rod Networks: Interplay of Junction Properties and Strut Rigidity\ Tsui, MichelleIslam, Mohammad F.
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| College
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Carnegie Mellon University
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| Date
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2019
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Ph.D.
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2019
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| Note
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176 p.
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| Abstract
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Random networks of filaments are microstructures ubiquitous in materials from paper, open cell foams, polymers, scaffolds in biological soft tissue to multifunctional nanostructured materials. Networks with relatively rigid filaments exhibit unique behavior that is sensitive to the interfacial interactions at junctions. However, experimental studies focusing on the effect of junctions with tunable properties on these networks is lacking. Previous treatments of filamentous microstructures such as open cell foams and filamentous biopolymer networks approximate junctions as completely rigid, or cannot isolate the effect of junction stiffness and dynamics due to significant rearrangement of the filament network depending on the cross-linker type and concentration. In this work, rigid single-walled carbon nanotube networks with junctions tunable independent of the network structure, are experimentally modified through crosslinking with either rigid or flexible polymeric crosslinkers. Resulting bulk mechanical behavior is determined through static and dynamic thermomechanical measurements and analyzed using concepts from polymer network treatments, previous computational studies, and previous work on carbon nanotube networks. It is determined that the bulk properties of the SWCNT networks are a direct function of the flexibility, strength, and viscoelasticity of the junction crosslinker. The effect of strut rigidity while keeping constant junction interactions is also investigated by chemically converting the SWCNT networks into boron nitride nanotube networks. In contrast, this modifies the filament rigidity but preserves the original van der Waals junction interactions. This work provides experimental evidence substantiating previously suggested deformation mechanisms as well as the results of computational simulations predicting the role of tunable junctions. It also presents microstructure to property trends transferrable to other rigid filament networks to guide the design of new materials with multifunctional properties such as thermal, biological, and self-healing behavior.
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Materials science
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Mechanics
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Nanotechnology
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Islam, Mohammad F.
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Carnegie Mellon University
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